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Ultrasound of the Month Diagnosis Index

Case 163 Medial Meniscus Extrusion

Medial meniscus extrusion is easily identified on ultrasound as triangle-shaped tissue extending beyond the margin of the medial compartment.

Meniscus extrusion suggests underlying meniscal tear which may not be visualized sonographically. Associated degenerative changes such as adjacent marginal osteophyte formation may also be seen.

Case 162 Tensor Fascia Suralis Muscle

The tensor fascia suralis is a rare accessory muscle of the knee. This muscle most commonly originates from the distal semitendinosus but can arise from any hamstring muscle and can insert into the medial gastrocnemius, posterior leg fascia, or Achilles.

Sonographic imaging of non-pathologic accessory muscles demonstrates echotexture identical to that of other normal muscles. This is important to recognize such that variant muscle anatomy is not mistaken for neoplasm.

Case 161 Pilomatrixoma (Calcifying Epithelioma of Malherbe)

Pilomatrixoma, also known as calcifying epithelioma of Malherbe, is a benign tumor of hair follicle matrix. Presents as a solitary, painless, and firm nodule on a hair-bearing surface.

More common in the pediatric population but may also occur in adults, with a bimodal distribution. Ultrasound can be used to differentiate these tumors from cysts and, if characteristic heterogeneous echotexture and calcifications (with or without posterior shadowing) are present, can suggest the correct diagnosis.

Case 160 Superficial Peroneal Nerve Transection and Tibial Fracture from Chainsaw Laceration

Deep lacerations result in possibility of injury to multiple structures, including nerves, bones, muscles, and tendons.

Scar along the path of the laceration helps to define the extent of injury on imaging. Ultrasound can reveal injury to structures which may not be suspected clinically.

Case 159 Calcium Hydroxyapatite Deposition in the Medial Collateral Ligament

Calcium hydroxyapatite deposition disease is a pathology in which calcific deposits form around and within joints. The most common location affected is the rotator cuff of the shoulder, but ligaments and tendons about other joints are also susceptible, and intra-articular involvement still more uncommon.

Treatment includes barbotage, a technique by which calcium hydroxyapatite deposits are lavagedand needled. Following barbotage, anesthetic and steroid is injected into the overlying soft tissues for anti-inflammatory effects and pain relief.

Case 158 Bilateral Peroneal Tendon IntrasheathSubluxation

Intrasheath subluxation refers to displacement of the peroneal tendons over each other in the retromalleolar groove. This is in the setting of an intact superior peroneal retinaculum, which prevents dislocation of the tendons out of the retromalleolar groove.

Patients typically experience the subluxation as a painful snapping or clicking sensation along the posterolateral aspect of the ankle upon ankle circumduction. Dynamic ultrasound is the imaging modality of choice to evaluate for this pathology.

Case 157 Wrist Ulnar and Radial Bursitis

The radial and ulnar bursae are synovium-lined structures that track along the flexor tendons of the wrist and hand at the level of the wrist, often communicating with the tendon sheaths that are found along these tendons at the level of the fingers.

The radial bursa tracks along the flexor pollicis longus tendon, while the ulnar bursa has three invaginations that track along the flexor digitorum superficialis and profundus tendons in the carpal tunnel.

Just like tendon sheaths, these bursae can become inflamed in patients with inflammatory arthritides, and can be a mode of spread of infection, such as mycobacterial infections.

Ultrasound is an excellent modality for identifying fluid in these bursae. Presence of hyperemia on power or color Doppler suggests active inflammation, and ultrasound is also excellent for safely guiding aspirations or injections of these bursae.

Case 156 Parsonage-Turner syndrome (Neuralgic amyotrophy)

Parsonage-Turner syndrome is a neurological disorder classically presenting with denervation in the upper extremity after an acute onset of intense pain. The pathophysiology of Parsonage-Turner syndrome is considered multifactorial and probably immune-mediated, although the exact cause or trigger is still uncertain.

The clinical history is important for diagnosis. On MRI and ultrasound, diffuse enlargement of the affected nerve with hourglass-like constrictions is highly suggestive of Parsonage-Turner syndrome. If the patient has residual symptoms after conservative therapy, surgical neurolysis at the sites of hourglass-like constrictions may be of benefit.

Case 155 Iliopsoas Bursitis

The iliopsoas bursa is located deep to the iliopsoas tendon as the tendon crosses the anterior rim of the acetabulum, functioning to reduce friction between the tendon and the acetabulum. Fluid in the iliopsoas bursa is usually due either to irritation of the iliopsoas tendon or fluid spontaneously decompressing from the hip joint. Fluid in the iliopsoas bursa can present with pain and/or mass-like lesion in the groin.

Ultrasound is an excellent modality for confirming the diagnosis of iliopsoas bursitis, and for guiding aspiration +/- cortisone injection. If there is any concern for the bursal fluid being infected, then the aspirated fluid should be sent for cell count and culture analysis.

Case 154 Inflammatory Arthritis

Inflammatory arthritis, such as rheumatoid arthritis and juvenile idiopathic arthritis, is an autoimmune disorder resulting in inflammation of joints and tendons. The various inflammatory arthritides differ in the typical age of presentation, distribution of joints involved, and serum markers. Imaging plays an important role in the diagnosis of and monitoring of inflammatory arthritides. Radiography, MRI, and ultrasound are all useful in the imaging of patients with an inflammatory arthritis.

On ultrasound, the hallmark of inflammatory arthritis is erosions, synovitis, and tenosynovitis. Synovitis on ultrasound is seen as combination of joint effusion, synovial proliferation, and hyperemia. Tenosynovitis on ultrasound is seen as fluid in and thickening of the tendon sheaths around tendons. Hyperemia, seen as increased vascularity on power or color Doppler, is specific for active inflammation.

Case 153 Schwannomatosis

Schwannomatosis is a genetic condition presenting as multiple benign tumors (schwannomas) of the peripheral nerves, similar to neurofibromatosis types I and II. Mutations in either the SMARCB1 or the LZTR1 gene, which encode for tumor suppressor proteins, are implicated in schwannomatosis.

Patients with schwannomatosis present with nerve related symptoms depending on the nerves affected. Unlike neurofibromatosis type I, development of malignant tumors is not a feature, and unlike neurofibromatosis type II, vestibular nerve involvement is not a feature in schwannomatosis.

If there is a concern for a nerve sheath tumor in any patient presenting with nerve symptoms, MRI or ultrasound would be the appropriate initial work-up. Masses along the course of a nerve or multiple nerves would be consistent with either neurofibromatosis or schwannomatosis. Additional tests, including MRI of the brain and genetic tests, would be required to differentiate among these three conditions.

Case 152 Piriformis Syndrome

Piriformis syndrome is abnormality of the piriformis muscle that can irritate the adjacent sciatic nerve, presenting as buttock pain with or without sciatica.

The existence of this entity is controversial, and MRI and ultrasound usually do not reveal any abnormality.
Treatment is also controversial, but if physical therapy fails, intramuscular botox injection has been described as a treatment option.

In experienced hands, ultrasound is an appropriate modality for guiding injections into the piriformis muscle.
CT-guidance is an alternative option but requires ionizing radiation.

Case 151 Longitudinal Split Tear of the Posterior Tibial Tendon

The posterior tibial tendon is an important flexor and invertor of the ankle, coursing posterior to the medial malleolus and inserting on multiple bones of the foot but primarily the navicular. Injury and degeneration of the posterior tibial tendon can occur in older patients or in patients with certain risk factors such as obesity and diabetes.

On imaging, posterior tibial tendon pathology can range from tendinosis, split tears, partial ruptures, to complete ruptures. Complete rupture of the posterior tibial tendon will lead to collapse of the longitudinal arch of the foot.

Case 150 Lateral Epicondylitis with Partial Thickness Extensor Tendon Tear

Lateral epicondylitis encompasses a spectrum of tendinopathy of the common extensor tendon with or without a superimposed tendon tear.

There are several treatment options available for lateral epicondylitis, including ultrasound-guided procedures.

Under ultrasound guidance, treatment options include tenotomy with or without platelet-rich plasma (PRP) injection, and cortisone injection.

Tenotomy involves needling the abnormal tendon including the site of the tear, and PRP injection, if performed, is done directly into the tendon.

Cortisone, in contrast, is injected around the tendon rather than into the tendon.

Ultrasound-guidance, compared to palpation-guided techniques, allows precise placement of the needle into the abnormal area of the tendon during tenotomy and injections.

Other injections that have been described include autologous blood, botox, and hypertonic dextrose.

Case 149 Posterior Intercondylar Notch Ganglion Cyst Arising from the ACL

Ganglion cysts are common sources of pain and soft tissue mass that arise from areas of soft tissue injury, such as ligaments and the joint capsule.

In the knee, the ACL is a common source of ganglion cysts.

Ganglion cysts of the knee are easy to diagnose on MRI. On ultrasound, ganglion cysts located deep may be harder to confidently diagnose.

Ganglion cysts arising from the ACL, similar to those occurring elsewhere, may be amenable to ultrasound-guided aspiration and injection.

Because these ACL cysts tend to decompress posteriorly, the procedure is performed with the patient prone, and care must be taken to avoid the popliteal vessels and the tibial and common peroneal nerves.

Case 148 Dislocating Long Head Biceps Tendon of the Shoulder

The long head biceps tendon normally courses within its tendon sheath in an osseous groove of the anterior humerus called the bicipital groove, kept in place by the transverse humeral ligament that forms the roof for the bicipital groove.

The long head biceps tendon is a common source of anterior shoulder pain; tendinosis, tenosynovitis, and tears can all be a cause of pain.

If the transverse humeral ligament is disrupted, the long head biceps tendon can become unstable and can sublux or dislocate out of the bicipital groove with shoulder motion.

Ultrasound is an ideal modality for assessing the long head biceps tendon.

Tendinosis, tenosynovitis, and tears of the tendon can be diagnosed on ultrasound, and the ability to perform a dynamic evaluation also allows ultrasound to diagnose conditions that are only seen with certain shoulder positions or motions, such as dislocation of the biceps.

Ultrasound also allows the radiologist to confidently attribute the tendon dislocation to the clicking felt by the patient and to assess whether it is the source of pain.

Case 147 Unintended Suturing of the Ulnar Nerve During Flexor Tendon Repair at the Elbow

This is a case of the ulnar nerve having inadvertently been sutured during intended flexor tendon repair.

The initial surgery had been performed at an outside institution. The orthopedic surgeon presumably thought the ulnar nerve was the abnormal flexor tendon, and it was sutured onto the medial epicondyle of the distal humerus.

Ultrasound is a great modality for assessing soft tissues including nerves. The outstanding spatial resolution of ultrasound allows direct visualization of foreign bodies such as suture, and size and morphology of the ulnar nerve that may be signs of nerve irritation can be assessed.

In this case, the diagnosis of inadvertent suturing of the ulnar nerve was confirmed by subsequent surgery at our institution.

Case 146 A2 Pulley Rupture 

The annular pulleys of the fingers are fibrous bands that hold the flexor tendons against the phalanges and provide a mechanical advantage to the flexor tendons.

Among the 5 annular pulleys, the A2 pulley, located at the level of the proximal phalanx, is the strongest.

A2 pulley injuries are common in rock climbers.

Both ultrasound and MRI are useful for diagnosing pulley injuries.

On ultrasound, disruption of the A2 pulley itself can be seen, but volar displacement of the flexor tendons away from the proximal phalanx, called “bowstringing”, is a secondary feature and is diagnostic.

Isolated disruption of the A2 pulley may be managed conservatively.

If conservative therapy is not successful, or if the A2 pulley disruption is accompanied by other injuries, surgical repair may be indicated.

Case 145 UCL Tear with Stener Lesion

Tear of the UCL of the thumb MCP joint is also called “gamekeeper’s thumb” or “skier’s thumb.”

Tear most commonly occurs at the proximal phalangeal insertion, sometimes resulting in an avulsion fracture.

When the torn UCL is significantly retracted and entrapped superficial to the adductor aponeurosis, it is referred to as a “Stener lesion.”

Stener lesions require surgical repair.

Case 144 Chondrocalcinosis

Chondrocalcinosis is calcium deposition in hyaline cartilage or fibrocartilage.

Chondrocalcinosis is nonspecific but most commonly represents calcium pyrophosphate dihydrate (CPPD) crystals.

In the wrist, chondrocalcinosis typically involves the TFCC, scapholunate ligament, and the lunotriquetral ligament.

CPPD deposition can have a variety of presentations, including chronic symptoms similar to osteoarthritis, and acute flares simulating gout, called “pseudogout.”

Case 143 Bipartite Medial Cuneiform

Bipartite medial cuneiform is a rare developmental variant, occurring in less than 1% of the population, in which the medial cuneiform forms as two separate bony components instead of a single bone.

The two components, dorsal and plantar, may be united by a synchondrosis, syndesmosis, or combination of the two.

Bipartite medial cuneiform may become a source of pain in adults.

Bone marrow edema on MRI is a clue that it may be the source of the patient’s pain.

Case 142 Cubital Tunnel Syndrome

Cubital tunnel is a fibro-osseous tunnel through which the ulnar nerve courses at the level of the elbow, and irritation or compression of the ulnar nerve in this tunnel is called cubital tunnel syndrome.

Ultrasound is an excellent modality for assessing the ulnar nerve at the level of the elbow.

Just like nerve irritation elsewhere, enlargement of the ulnar nerve and loss of its normal fascicular architecture are signs of cubital tunnel syndrome.

10 mm2 is reported as the cutoff for normal cross-sectional area of the ulnar nerve at the level of the cubital tunnel.

Ultrasound, compared to MRI, has the added benefits of being able to assess for a Tinel’s sign and being able to perform dynamic maneuvers to assess nerve entrapment.

Case 141 Morel-Lavallée Lesion

Morel-Lavallée lesions are fluid collections that occur in the subcutaneous fat, most commonly over the greater trochanter.

The mechanism of injury is a closed degloving injury, and the fluid collection may be filled with serous fluid, bloody fluid, or debris.

Ultrasound or MRI will show an encapsulated fluid collection containing simple or complex fluid, with or without debris, the latter representing fat or blood products.

Treatment can start with aspiration, but surgical resection of the capsule may be necessary if fluid reaccumulates in the collection.

Case 140 Rheumatoid Arthritis with Rice Bodies

“Rice bodies” have been reported as a finding in synovial or bursal spaces, manifesting as numerous uniform-sized rice-like foci.

Case reports have associated rice bodies with mycobacterial infection, rheumatoid arthritis, and synovial chondromatosis.

Imaging may help differentiate these diagnoses, but arthrocentesis or surgical removal may be necessary for diagnostic and therapeutic purposes.

In the current patient, culture analysis of the fluid in the subacromial subdeltoid bursa was negative for any bacteria, and the patient was ultimately diagnosed with rheumatoid arthritis.

Case 139 Inflammatory Flexor Tenosynovitis

Tenosynovitis is inflammation of the tendon sheath, and the differential diagnosis includes posttraumatic, inflammatory, and infectious etiologies.

Fluid in the tendon sheath, often with surrounding soft tissue edema, is the hallmark of tenosynovitis on imaging.

MRI and ultrasound are both excellent imaging modalities for diagnosing tenosynovitis.

Ultrasound has the additional advantage of being able to detect hyperemia on Doppler, which increases specificity for active inflammation.

In the current case, the patient subsequently gave a history of injury to the finger while gardening, and the ultimate diagnosis was septic tenosynovitis by MAI (Mycobacterium avium-intracellulare).

Case 138 Hamstring Tendon Avulsion

Hamstring strains and tears are common sports-related injuries, occurring due to excessive stretch or sudden load.

Strains can occur in the central muscle belly or at the myotendinous junction, while avulsion of the tendon can occur at its origin at the ischial tuberosity.

Unlike muscle strains, hamstring tendon avulsions are usually treated operatively.

Imaging, usually MRI, can help identify site of hamstring injury.

Ultrasound is less sensitive than MRI for detection of low-grade muscle strains but can identify tendon tears and avulsions. 

Case 137 Angiolipoma

Angiolipomas are benign neoplasms made up of a combination of mature adipocytes and small blood vessels.

They commonly present as multiple tender subcutaneous masses, forearm being the most frequent site.

On ultrasound, the imaging features can overlap with those of lipomas, but angiolipomas tend to be more heterogeneous, generally more hyperechoic (brighter), and smaller than lipomas.

Vascularity may not be detectable in all angiolipomas under ultrasound, but if detected, suggests a diagnosis of angiolipoma.

Angiolipomas are benign and excision is curative.

Case 136 Carpal Tunnel Syndrome

The carpal tunnel is a fibro-osseous tunnel in the wrist, partly defined by the transverse carpal ligament (flexor retinaculum), through which runs the median nerve as well as the flexor pollicis longus and flexor digitorum superficialis and profundus tendons.

Carpal tunnel syndrome is median nerve neuritis due to compression and irritation of the nerve within the carpal tunnel.

The cause of carpal tunnel syndrome is usually idiopathic, but anything that decreases the area of the carpal tunnel can potentially contribute to carpal tunnel syndrome.

Carpal tunnel syndrome is usually diagnosed by a combination of physical exam and electrodiagnostic tests.

Ultrasound can easily identify the median nerve and other structures within the carpal tunnel and thus has a role in assessing patients with suspected carpal tunnel syndrome.

Much has been published regarding the ultrasound findings that suggest carpal tunnel syndrome.

The most extensively studied is the size of the median nerve, expressed as the cross-sectional area.

Compression of the median nerve within the distal segment of the carpal tunnel results in enlargement of the nerve immediately proximal to the site of compression, and >12 mm2 is often quoted as being suggestive of carpal tunnel syndrome.

Thickening and palmar bowing of the transverse carpal ligament, abrupt caliber change to the nerve at the site of compression (“notch sign”), and flattening of the median nerve have also been described as being suggestive of carpal tunnel syndrome.

Case 135 Developmental Dysplasia of the Hip (DDH)

Developmental dysplasia of the hip (DDH) is a condition in which a baby is born with a shallow acetabulum and undercoverage of the femoral head by the acetabulum.

Early diagnosis is important as it allows early treatment, minimizing the need for surgery, while missed diagnosis can lead to abnormal gait, limb length discrepancy, and premature osteoarthritis.

Ultrasound is the first line imaging modality for evaluating babies suspected of DDH.

Diminished α angle (< 60°) and less than 50% coverage of the femoral head are indicative of DDH.

If detected early, DDH is treated with a Pavlik harness. Delayed diagnosis or severe cases may require surgical reduction and Spica casting.

Case 134 EPL Tendon Impingement by Screw Tip

Fracture of the distal radius is often treated with hardware, most commonly volar plate and screws.

If a tip of one of the screws is proud with respect to the dorsal cortex, it can impinge on or irritate one or more of the dorsal extensor tendons.

If the impingement is severe and it is not addressed, it can lead to tendon rupture.

Ultrasound is an ideal modality for assessing the relationship of a tendon with hardware, superior to MRI, CT, or radiographs.

Ultrasound allows direct visualization of the impingement and secondary changes to the tendon such as tendinosis, split tear, tenosynovitis, and tendon rupture.

Case 133 Adventitious Bursitis

Adventitious (Adventitial) bursitis is a fluid collection that forms at pressure points or sites of friction, due to chronic irritation of the soft tissues.

In the foot and ankle, contact with ill-fitting shoes is a common cause of adventitious bursitis.

Adventitious bursitis is not normally present, in contrast to anatomic bursae such as the retrocalcaneal bursa.

Treatment is conservative, including avoiding the ill-fitting shoe, but refractory cases may be amenable to ultrasound-guided aspiration and cortisone injection.

Case 132 Ankle Joint Synovitis

Ankle joint synovitis is a common source of ankle pain, presenting with a swollen, painful joint.

There are many causes of ankle joint synovitis, including osteoarthritis, inflammatory arthritides, and OCD lesions.

On ultrasound, synovitis presents as joint effusion often with associated hyperemia on power Doppler. If the cause is osteoarthritis, arthritic changes to the joint, such as dorsal osteophytes, may be visible on ultrasound.

Treatment may involve physical therapy and ultrasound-guided cortisone injections. If these fail to adequately treat, surgery (arthrodesis vs arthroplasty) is an option.

Case 131 Vascular Malformation

Vascular malformations are a group of congenital anomalies of vessel morphogenesis that can present at any age.

The International Society for the Study of Vascular Anomalies (ISSVA) updated the classification in 2014 to include capillary, venous, lymphatic, and arteriovenous malformations among the simple vascular malformations.

They are benign but can grow rapidly at times of hormonal stimulation such as puberty, and can be complicated by hemorrhage, thrombosis, or infection.

MRI is useful for mapping the full extent of the lesion.

Ultrasound can be helpful in confirming the diagnosis if the MRI is not definitive, and doppler evaluation can further characterize the type of vascular malformation.

Treatment depends on size and patient symptoms. Many can be treated non-invasively by an interventional radiologist, either using catheter-directed sclerotherapy or embolization.

Case 130 Acute ATFL Tear

The anterior talofibular ligament (ATFL) is one of three ligaments that make up the lateral collateral ligament complex of the ankle; the other two are the calcaneofibular ligament and the posterior talofibular ligament.

The ATFL is the most commonly injured ligament in the ankle. Ankle “sprain” due to inversion and plantar flexion typically results in tear of the ATFL, followed by the calcaneofibular ligament and then the posterior talofibular ligament.

MRI is traditionally used to diagnose ligamentous injuries in the ankle.

The ATFL is also well evaluated on ultrasound.

On ultrasound, an intact ATFL should maintain a homogenous fibrillar appearance between the distal fibula and the talus.

Torn ATFL will manifest as a diffusely thickened and disorganized bundle of fibers or a frankly discontinuous ligament.

In the chronic phase, a torn and deficient ATFL may manifest as an attenuated or absent ligament.

A torn ATFL which results in instability may require surgical reconstruction.

Case 129 Nursemaid’s Elbow

Nursemaid’s elbow refers to subluxation of the annular ligament, which becomes interposed between the capitellum and the radial head.

Mechanism of injury is sudden longitudinal traction to the hand or forearm with the elbow extended and forearm pronated.

The person pulling the arm may have heard a pop or click at the time of injury, and the child will present with refusal to move the elbow.

Radiographs usually are normal (in 25%, the radiocapitellar line may project lateral to the center of capitellum).

On ultrasound, presence of soft tissue interposed between the radial head and capitellum, representing the subluxed annular ligament, is diagnostic.

Ultrasound has the advantages of being quick, radiation-free, and being able to easily scan the contralateral elbow for comparison.

Treatment is conservative, consisting of casting with the forearm in supination or hyperpronation.

Case 128 Calcific Tendinitis of the Flexor Tendon Origin

Calcific tendinitis is a source of pain due to deposition of calcium hydroxyapatite crystals in the substance of a tendon.

Calcific tendinitis most commonly occurs in the shoulder (rotator cuff tendons), with the hip being the second most common site, but it can occur anywhere, including the elbow.

Calcific tendinitis can be diagnosed on xray, MRI, or ultrasound; ultrasound has the advantage of allowing for correlation of the calcific deposit with the patient’s site of symptomatology and allowing for guided therapeutic intervention at the same time.

In ultrasound-guided barbotage, a needle is safely placed into the calcific deposit and a lavage and aspiration are repeatedly performed to break up the calcium and remove some of the calcium.

Cortisone is usually injected at the end of the procedure for therapeutic purposes.

Although this procedure has been most commonly described in the shoulder, it can be performed anywhere in the body, provided that it can be accessed using ultrasound guidance.

If ultrasound-guided barbotage fails to provide pain relief, surgical debridement and repair of the affected tendon may be indicated.

Case 127 FHL tenosynovitis distal to the knot of Henry

The FHL courses from the ankle to the great toe by passing through the tarsal tunnel.

The most common site of FHL impingement is at the posterior ankle, occurring in those who perform repetitive plantar flexion of the great toe.

FHL impingement can also occur at the master knot of Henry, where the FHL and FDL tendons cross over each other.

These tendons can easily be assessed using ultrasound.

On ultrasound, FHL tenosynovitis will present with thickening of the tendon as well as its tendon sheath.

Added advantages of ultrasound are the ability to perform dynamic maneuvers (e.g. applying tension to the FHL tendon by dorsiflexing the great toe), as well as applying pressure with the ultrasound probe to pinpoint the area of patient’s symptomatology (“sonopalpation”).

Case 126 High-grade Pleomorphic Sarcoma of the Lower Leg

Undifferentiated pleomorphic sarcoma (UPS), formerly known as malignant fibrous histiocytoma (MFH), is the most common soft tissue sarcoma in adults with an aggressive behavior and poor prognosis.

They have a predilection for the lower and upper limbs, but can also arise in the retroperitoneum or the peritoneal cavity.

Clinically, these tumors present as a rapidly growing mass.

Most UPS are of high grade (grades 3 and 4), will have frequently metastasized at time of diagnosis, and can locally recur even with aggressive treatment.

MRI is the imaging modality of choice for assessing these tumors.

Ultrasound will show a nonspecific solid mass, but ultrasound has the advantage of allowing for image-guided soft tissue biopsy should a tissue diagnosis be required.

Case 125 Polyethylene Dissociation in Reverse Total Shoulder Arthroplasty

Instability, including dislocation, is a common complication in reverse total shoulder arthroplasty, reported in 5% of patients.

Polyethylene dissociation occurs much less frequently, but when it does occur, it precludes closed reduction.

The polyethylene liner is not easily visible on radiographs as it is hypodense (dark), unlike the metallic components.

Because the polyethylene is usually positioned between the glenosphere and the humeral component, the two components appearing to be closer together is a radiographic sign of polyethylene dissociation.

On radiographs, the displaced polyethylene liner may be visible as a dark structure surrounded by the more hyperdense (brighter) soft tissues around it.

Ultrasound is another modality which can identify the displaced polyethylene liner if one is familiar with the ultrasound appearance of the liner.

Case 124 Intra-articular Loose Body of the First MTP Joint

Loose bodies are free fragments, usually cartilaginous, calcified, or osseous, that are inside the joint. A foreign body can also be a loose body in the setting of prior penetrating injury or surgery.

If the loose body irritates that joint, it can lead to synovitis and present with swelling of the joint. If the loose body is in an area close to the skin, it can also present as a palpable abnormality, as in the current patient.

Ultrasound is a good imaging modality for identifying synovitis, and if the loose body is palpable to the patient, the source of the palpable abnormality can be identified on ultrasound.

Other sources of a palpable nodule about a joint include ganglion cysts, soft tissue neoplasms, osteophytes, vascular lesions such as thrombophlebitis or pseudoaneurysms, and proud surgical screws/implants.

Loose bodies that are deep inside a joint may be more easily diagnosed on MRI.

Case 123 Plantar Plate Tear

The plantar plate, together with the collateral ligaments, is important for sagittal stability of the lesser MTP joints.

Tear of the plantar plate can result in metatarsalgia, instability, and chronic deformity such as crossover toe, hammertoe, and claw toe.

MRI has historically been the first line imaging modality for assessing the integrity of the plantar plate.

Ultrasound may be a good imaging option for assessing the plantar plate for its superior spatial resolution, lower cost, and ability to perform a focused exam.

Case 122 Achilles Paratenonitis

The Achilles tendon lacks a true tendon sheath but has a single-cell membrane-like tissue immediately posterior to it known as the paratenon.

Chronic overuse of the Achilles can result in paratenonitis, which is irritation of the paratenon due to repetitive microinjury.

On ultrasound, the paratenon of the Achilles tendon is normally thin and barely perceptible.

In paratenonitis, the paratenon is thickened and hypoechoic (darker) and there may be associated hyperemia on power Doppler. This has a different appearance than tendinosis, which would manifest as abnormal thickening and hypoechoic change of the Achilles tendon itself.

The management of Achilles paratenonitis is the same as that for tendinosis, including rest, ice, NSAIDS, and training modification.

Case 121 Thrombosis of the Lateral Plantar Vein 

There are two sets of plantar veins, one coursing along the medial half of the foot and the other coursing along the lateral half of the foot together with the respective plantar nerves and arteries, which all traverse the tarsal tunnel.

Thrombosis of the plantar veins is uncommon, but can present with foot pain not unlike plantar fasciitis or a stress fracture.

Either ultrasound or MRI can be used for diagnosis. Plantar vein thrombosis is typically treated with anticoagulation as there is a risk of propagation to more proximal veins of the deep venous system as well as pulmonary embolism.

Case 120 Pretibial Abscess

An abscess is a fluid collection containing infectious material/pus, usually due to a bacterial infection.

Chronic underlying disease such as an inflammatory arthritis, or immunosuppressive therapy may be a predisposing factor.

On ultrasound, an abscess manifests as a fluid collection that is complex in appearance (thickened wall, internal echoes, internal septations) with associated hyperemia on color or power Doppler.

Ultrasound-guided aspiration is important for isolating the offending organism, and may be curative if also treated with antibiotics.

Case 119 Gout

Gout is a crystal deposition disease in which tophi made up of monosodium urate form in soft tissues, including within joints, and incite an inflammatory arthritis.

Elevation of serum uric acid is suggestive, but a definitive diagnosis requires the identification of negatively birefringent monosodium urate crystals in the affected site.

Ultrasound is a cost-effective imaging modality for assessing a joint that could potentially be affected by an inflammatory arthritis.

Ultrasound also has the advantage of allowing guided arthrocentesis.

On ultrasound, the classic features of a joint affected with gout include:

  • hyperechoic mass-like intraarticular deposits reflecting tophaceous material 
  • a layer of hyperechoic material lining the articular cartilage, referred to as the “double contour sign”, representing uric acid crystals 
  • Accompanying synovitis (joint effusion with synovial hyperemia).

Case 118 Partial (Incomplete) Laceration of the Median Nerve 

Peripheral nerves as well as tendons of the upper extremities are vulnerable to lacerations due to penetrating trauma.

Nerve lacerations can be partial (involving some but not all of the nerve fascicles) or complete.

For peripheral nerves of the extremities, ultrasound is the ideal initial imaging modality for assessing for structural injury because of its high spatial resolution, easy access, and quick scan time.

Ultrasound is very useful for characterizing the degree of laceration, presence of fluid collections, and presence of retained foreign bodies.

Case 117 Morton's (Interdigital Neuroma

Interdigital (Morton's) Neuroma is a common source of pain in the ball of the foot,usually occurring in either the 3rd or 2nd webspace.

“Neuroma” is a misnomer, as it represents fibrosis around the digital nerve rather than a true tumor.

Several factors are considered to be risk factors for the development of Morton’s neuromas, including ill-fitting shoes, certain foot deformities, and repetitive trauma from running.

Both ultrasound and MRI are excellent modalities for diagnosing Morton’s neuromas.
Ultrasound has the added advantage of allowing for image-guided cortisone injection or ablation.

If noninvasive treatments are not successful, surgical resection is curative.

Case 116 Bifid Median Nerve with a Persistent Median Artery 

The bifid median nerve has a prevalence of 3% in the general population.

In this normal variant, the nerve divides into two bundles in the distal forearm rather than dividing into its branches just distal to the carpal tunnel, which is the most common anatomy.

The bifid median nerve may be accompanied by an artery, the persistent median artery, coursing between the two bundles.

The bifid median nerve, with or without a persistent median artery, is thought to be a risk factor for carpal tunnel syndrome, as it is overall larger than a normal median nerve and thus more prone to compression in the carpal tunnel.

The presence of a bifid median nerve with or without a persistent median artery is important for the hand surgeon to be aware of preoperatively so that an inadvertent injury to the nerve or the artery can be avoided.

Case 115 Ulnar Nerve Dislocation at the Elbow 

Dislocating ulnar nerve is the most common source of a snapping sensation along the medial aspect of the elbow.

The ulnar nerve normally courses posterior to the medial epicondyle of the distal humerus, but in approximately 15% of the population, the nerve can dislocate anterior to the medial epicondyle, causing a snapping sensation.

May otherwise be asymptomatic or may be associated with ulnar neuritis.

A less common cause of snapping along the medial aspect of the elbow is snapping of the medial head of the triceps.

Ultrasound is the best modality for assessing the source of a snapping sensation of the medial aspect of the elbow.

Ultrasound, compared to MRI, is more easily tolerated, more accessible, and quicker.

But the greatest advantage of ultrasound over MRI is the ability to perform dynamic maneuvers, which is necessary to diagnose either a dislocating ulnar nerve or medial head of the triceps.

Treatment is usually conservative, although patients with symptomatic neuritis may require surgical transposition of the ulnar nerve.

Case 114 Rotator Cuff Tendinopathy with SubacromialImpingement of the Shoulder  

Rotator cuff tendinopathy is a common cause of shoulder pain in the adult.

Subacromialimpingement is often associated with rotator cuff tendinopathy, and it refers to structural abnormalities encroaching or impinging on the rotator cuff, usually the supraspinatus tendon, such as enthesophytesof the acromion or osteophytes of the acromioclavicular joint.

Both MRI and ultrasound are accurate modalities for assessing the rotator cuff and for impingement.

Ultrasound has the advantages of being quicker, more accessible, and more tolerable for the patient.

On ultrasound, thickening and heterogeneity of any of the four rotator cuff tendons are features of tendinopathy/tendinosis.

Partial thickness or full thickness discontinuity of the tendon represents a tear of the rotator cuff, usually in the background of tendinopathy/tendinosis.

Thickening and/or fluid distension of the subacromialsubdeltoidbursa can be seen with rotator cuff pathology.

On ultrasound, bunching or “crowding” of the bursa during abduction of the shoulder is a fairly specific sign of subacromialimpingement.

Case 113 Jersey Finger (Avulsion of the flexor digitorum profundus tendon)

34-year-old female with inability to flex the distal interphalangeal joint of the ring finger after recent injury.

Avulsion of the flexor digitorum profundus (FDP) off its attachment on the base of the distal phalanx typically occurs in full-contact sports such as football.

It is also called “jersey finger”, as this injury commonly occurs when a player grabs the opponent’s jersey and the finger is injured as the jersey is yanked away.

The severity of injury depends on the degree of retraction of the avulsed tendon and whether there is a fracture involved (Leddy and Packer classification).

Xray is the first line imaging modality to assess for fractures. Ultrasound is a quick and accurate exam to identify the avulsed tendon and localize the tendon stump.

Treatment is surgical, typically direct tendon repair unless the injury is chronic.

Case 112 Trigger Finger

77-year-old female with trigger finger of the index finger.

Trigger finger, also known as stenosingtenosynovitis, is a painful condition of the finger accompanied by either a locking or catching sensation. The most common cause of trigger finger is inflammation or scarring of the A1 pulley, prohibiting the flexor digitorumprofundusand superficialistendons from gliding smoothly. On ultrasound, the A1 pulley can be easily seen, and it is often thickened in patients with trigger finger.

Ultrasound-guided cortisone injection into the tendon sheath is an effective treatment for trigger finger. Surgical release of the A1 pulley may be required in refractory cases. Ultrasound-guided percutaneous release of the A1 pulley is also an option at some centers.

Case 111 Hourglass Constriction of the Deep Branch of the Radial Nerve

11-year-old male with left radial nerve palsy after conservative treatment of a radial head fracture.

Hourglass constriction is an uncommon entity which has become increasingly recognized as a cause of acute spontaneous peripheral nerve palsy. It has been described in various nerves of the upper extremity, mainly at the level of the elbow and forearm.

There is some disagreement in the published literature about the relationship of hourglass constriction to idiopathic neuralgic amyotrophy(Parsonage-Turner syndrome), with some researchers differentiating the two entities and some considering the two as the same entity. Both ultrasound and MRI can be useful for assessing patients presenting with acute nerve palsy.

Advantages of ultrasound over MRI include greater anatomic detail especially for smaller nerves; faster, less expensive, and more tolerable exam; and the ability to compare to the contralateral limb. Focal constricted appearance of the nerve in the background of a diffusely enlarged segment of the nerve is the hallmark of hourglass constriction on both ultrasound and MRI. Treatment is also variable, but surgical neurolysismay be indicated.

Case 110 Intersection Syndrome

71-year-old male with dorsal lateral wrist pain radiating into the hand.

Intersection syndrome is an overuse disorder resulting in pain along the dorsal aspect of the distal forearm and wrist. Chronic friction at the site of crossover of the extensor tendons causes tendinosis and tenosynovitis.

Intersection syndrome can occur at either of two sites: where the first dorsal compartment tendons cross over the second dorsal compartment tendons (“proximal intersection”) or where the third dorsal compartment tendon crosses over the second compartment (“distal intersection”). The current case is an example of distal intersection syndrome.

Treatment starts with conservative treatment, including splinting and cortisone injection into the tendon sheaths of the affected tendons. Surgical release maybe indicated if conservative management fails.

Case 109 Pre-patellar Gouty Tophus

76-year-old male presents with left knee pain and swelling.


Subsequent ultrasound guided steroid injection into the pre-patellar nodule/collection was then performed.


  • Epidemiology: Males over the age of 40
  • Etiology: Hyperuricemia resulting in the deposition of monosodium urate crystals in and around joints
    • Often associated with excessive meat and alcohol intake
  • Acute gouty flare: Painful, red, swollen joint, most characteristically involving the first metatarsophalangeal joint
  • Chronic gout: Tophaceouscollections of solid urate crystals about joints and bursae with associated destructive changes
  • Treatment:
    • Acute: NSAIDs, colchicine, steroids, cytokine blocking agents
    • Chronic: Xanthine oxidase inhibitors, uricosuric drugs

Imaging Findings:

  • Radiography:
    • Eccentric punched out “rat bite” erosions with sclerotic margins and overhanging edges
    • Hyperdensetophaceousnodules with or without calcification
    • Maintenance of the joint space until late in the disease
    • Olecranon and prepatellarbursitis
  • Ultrasonography:
    • Heterogeneous hyperechoic synovitis
    • Erosions
    • Superficial irregular hyperechoic crystal deposition along hyaline cartilage
    • Heterogeneous hyperechoic tophi with anechoic rims
  • CT:
    • Dual-energy CT allows for detection of monosodium urate crystals, as well as for assessment of their amount and distribution
  • MRI
    • Gouty tophi demonstrate intermediate or low T1 intensity, variable T2 intensity and homogeneous contrast enhancement

Case 108 Compression of the Deep Branch of the Radial Nerve/Posterior Interosseous Nerve

46-year-old male with weakness with finger extension.

The deep branch of the radial nerve is one of the two terminal branches of the radial nerve, the other being the superficial branch. Compression of the deep branch can occur at several different points and can present as either radial tunnel syndrome or posterior interosseous nerve (PIN) syndrome. Radial tunnel syndrome presents as pain without motor symptoms, while PIN syndrome presents as weakness. Ultrasound can be useful for evaluating patients presenting with either radial tunnel syndrome or PIN syndrome. Soft tissue masses or anatomical variants causing nerve compression may be visible on ultrasound, although fibrous bands may not be appreciable.

Case 107 Iatrogenic Transection of the TibialNerve in The Tarsal Tunnel

75-year-old female with numbness of the plantar aspect of the foot after recent ankle replacement.

Injury to the structures of the tarsal tunnel, including that of the tibialnerve, can occur during ankle replacement.
The tibialnerve as well as its main branches, the medial and lateral plantar nerves, can be well visualized under ultrasound. Transection of the nerve results in disruption of all of the individual fascicles of the nerve as well as the perineuriumand the epineurium. Transection may require treatment by nerve grafting. Other abnormalities of the tibialnerve that may be appreciated on ultrasound include incomplete laceration, neuroma formation, and extrinsic compression by pathology such as cysts, soft tissue masses, or scar tissue.

Case 106 Foreign body within the peroneal tendon sheath with associated tenosynovitis and peroneus brevis tendon tear

47-year-old female presents with left ankle pain and swelling 10 days after rolling her ankle while hiking in the woods, when she felt a splinter pierce the top of her foot.


  • Removal of a 1.5 cm splinter from the peroneal tendon sheath
  • Peroneus brevis debridement and repair


  • Retained soft tissue foreign bodies typically result from penetrating injury.
  • Foreign bodies are most commonly wood, glass, or metal structures.
  • Retained foreign objects result in a surrounding inflammatory reaction and with time may form encasing granulation tissue.
  • It is crucial to identify a foreign body before it results in infection or causes damage to the surrounding structures.

Imaging Findings:

  • Radiography:
    • Initial work up
    • However, many foreign bodies, such as wood and plastic, will not be seen on plain films as they are not radio-opaque.
  • Ultrasonography:
    • Echogenic object with posterior acoustic shadowing
    • A hypoechoic rind of inflammatory tissue with associated vascularity may also be seen

Case 105 Synovial Osteochondromatosisof the Posterior Subtalar Joint

48-year-old female with chronic hindfoot pain.

Synovial osteochondromatosisis a proliferative metaplasia of the synovium affecting one joint. Also known as synovial chondromatosisif the lesion is not calcified. Can be a source of slowly progressive joint pain and limited range of motion. Most commonly affects large joints, with the knee being the most frequently involved joint but also occurring in the hip, elbow, and shoulder.

On X-ray and CT, calcified bodies may or may not be seen depending on the degree of ossification. On MRI, synovial osteochondromatosismanifests as hypertrophied synovium which is hypointenseon T1-weighted sequences and hyperintenseon T2-weighted and proton density sequences. Punctate hypointensebodies within the lesion represent mineralized portions of the lesion. On ultrasound, a synovial-based mass showing hyperechoic foci consistent with calcification is suggestive. Surgical resection and synovectomy are curative, although recurrence can occur.

Case 104 Tendon rupture of EPL

20-year-old male with inability to extend the thumb three months after fracture of the distal radius treated conservatively.

EPL rupture is a common complication after fracture of the distal radius.

Fracture of the distal radius often goes through Lister’s tubercle, and since the EPL courses adjacent to Lister’s tubercle, this tendon is vulnerable to irritation and eventual tear if the fracture results in an irregular contour or jagged edge along Lister’s tubercle.

Because the EPL, along with all other tendons of the wrist, lies relatively superficial, they are well evaluated on ultrasound. Even before frank rupture, fraying of the tendon and fluid in the tendon sheath are signs of irritation.

Case 103 Morel-Lavallee Lesion

24-year-old male presents 4 months status post polytraumafrom a motor vehicle accident.


  • Post-traumatic closed degloving injury


  • Traumatic shearing and separation of the subcutaneous tissues from the underlying fascia,yielding a potential space in the perifascialplane, which may contain blood, lymph, debrisand fatty tissue.
  • The collection may resolve on its own or may develop a capsule and persist.


  • Most commonly occurs over the greater trochanter; however, may also be seen over theflank, buttocks and knee.

Radiographic features

  • Ultrasound: Anechoic, hypoechoic, or hyperechoic ovoid encapsulated fluid collection between thesubcutaneous fat and fascia, which may contain echogenic debris and maydemonstrate associated fluid-fluid levels.
  • MRI: Well-defined ovoid fluid collection superficial to the fascia, which demonstrates variablesignal intensity and possible associated fluid-fluid levels and septations.


  • Acutely, conservative management with elastic compression bandages may be utilized forlesions that have not become encapsulated.
  • If there is no resolution, percutaneous drainage and sclerodesiswith sclerosantagents, suchas talc and doxycycline, may be effective.
    • Sclerotherapy causes scarring in an attempt to prevent fluid reaccumulation.
  • However, surgical drainage and open debridement of the capsule may be required to preventfluid re-accumulation.

Case 102 Intramuscular Hematoma of the Vastus Intermedius

26-year-old professional football player with thigh tightness after injury.

A tear or strain of the muscle can result in an intramuscular hematoma, which can be a source of persistent pain and delayed healing. Both MRI and ultrasound are excellent modalities for diagnosing intramuscular hematomas of the extremities such as in the thigh. Ultrasound has the added benefit of being more cost-effective and more readily available compared to MRI. Additional benefit of ultrasound is the ability to guide percutaneous interventions, such as aspiration of the hematoma.

Fluid collections such as hematomas can have a variety of appearances on ultrasound based on the internal content and whether they are clotted. Simple fluid tends to be “anechoic” or black on ultrasound, while complex or clotted fluid tends to be “hyperechoic” or similar in brightness to muscle. Hyperechoic fluid, such as clotted blood, may not be drainable percutaneously and the radiologist often can predict how easily a collection would be drainable based on the ultrasound appearance of the collection.

Case 101 Tendinosis and Chronic Partial Tear of the Achilles Tendon

57-year-old male with chronic Achilles pain.

Achilles tendinopathy is a relatively common condition in both athletes and non-athletes, manifesting as activity-related pain in the Achilles tendon. On imaging, tendinopathy manifests as tendon thickening with abnormal architecture, and can progress to partial tears or full-thickness rupture. Both MRI and ultrasound are accurate modalities for assessing tendinosis and tears of the Achilles tendon.

Ultrasound has the advantage of being able to apply Doppler interrogation, which identifies hyperemia related to the tendon, which is one sign of active inflammation. Another advantage of ultrasound over MRI is that ultrasound can be used for guiding percutaneous treatment.

PRP (Platelet-rich plasma) injection while performing tenotomyor needling at the site of abnormality is a potential treatment option for chronic recalcitrant tendinopathy of any tendon, including that of the Achilles tendon.

Case 100 Anterior Inferior Iliac Spine (AIIS) Avulsion

An 18-year-old male presents with right thigh pain and weakness without recollection of a specific injury.


  • 14-17 years of age
  • Males > Females
  • Athletic activities that require kicking a ball


  • Eccentric contraction of the rectus femoris, which results in sudden hip joint extension with a flexed knee joint
  • Clinical Presentation
  • Sudden pop
  • Anterior hip pain
  • Hip flexion weakness
  • Antalgic gait


  • Radiographs:
    • Can identify an avulsed osseous fragment; however, radiographs may be negative prior to apophysealossification or in the setting of a nondisplaced apophysealavulsion injury
    • Marked callus formation may be seen radiographically, which may be misinterpreted as an infectious or neoplastic process
  • MRI:
    • Allows for demonstration of a retracted coiled tendon attached to an avulsed apophysis


  • Conservative nonoperative management
  • Bed rest, ice, and activity modification
  • Two weeks of hip flexion to minimize extending the involved muscle and apophysis
  • Four subsequent weeks of guarded weight bearing

Case 99 Neuroma-in-continuity of the Ulnar Digital Nerve to the Thumb

29-year-old female with numbness along the ulnar aspect of the thumb since laceration with glass over the 1st web of the hand.

Post-traumatic neuromas can occur either as a stump neuroma if the nerve is amputated or a neuroma-in-continuity if the nerve is transected but the two ends of the nerve are not retracted from each other.

“Neuroma” is a misnomer as it does not represent a neoplasm but rather scar formation around the injured nerve. Both ultrasound and MRI are useful modalities for identifying post-traumatic neuromas, although ultrasound is more accurate for small neuromas immediately beneath the skin such as in this case.

On ultrasound, post-traumatic neuromas manifest as areas of focal thickening and disorganized architecture of the nerve. Ultrasound is also useful for guiding therapeutic injections or ablations of the neuroma, and for preoperative mapping.

Case 98 Soft Tissue Abscesses of the Ankle

40-year-old male with recent tibiotalocalcaneal arthrodesis with failure of the arthrodesis and progressive swelling in the anterior aspect of the ankle.

Fluid collections in the postoperative setting may represent seromas, hematomas, or abscesses.
The imaging appearance of these different types of fluid collections can overlap, although certain features can suggest one diagnosis over another.

Ultrasound is an ideal modality for localizing fluid collections in the soft tissues.

On ultrasound, wall thickening, surrounding hyperemia, internal septations, and sinus tracts are features, if present, that suggest that a fluid collection may be an infected collection/abscess.

Sample of fluid is required for definitive diagnosis and for identifying the offending organism; one advantage of ultrasound is that it can be used to guide aspiration of the fluid collection.

Case 97 Pes Anserine Tendinitis

24-year-old male soccer player presents with medial left knee pain.

Pes anserinus, which is Latin for “goose’s foot”, describes the webbed footlike configuration of the joint distal insertion of the sartorius, gracilis and semitendinosus tendons onto the proximal aspect of the anteromedial tibia.

Pes anserine bursitis/tendinitis typically affects older individuals with arthritis as a consequence of constant friction with underlying osteophytes; however, young runners may suffer from this condition as well due to repeated valgus stress and recurrent microtrauma.

The clinical presentation consists of medial knee pain and swelling that is exacerbated by climbing or going down stairs.

The treatment includes rest, NSAIDS, physical therapy, and/or therapeutic bursal injection with anesthetic and/or cortisone.

Case 96 Popliteal (Baker’s) Cyst and Ganglion Cyst of The Popliteal Fossa of the Knee

Two patients who were referred to the ultrasound department for ultrasound-guided aspiration of a cyst in the popliteal fossa of the knee.

Palpable mass or fullness in the back of the knee is a common clinical scenario for which the first line imaging modality is ultrasound. Ultrasound is a fast, accurate, and cost-effective modality for identifying the source of a mass in the back of the knee. Cysts, including Baker’s cysts and ganglion cysts, are commonly found, but less common sources of “masses”, including thrombosed veins, popliteal artery aneurysms, hematomas, and tenosynovitis, can be accurately diagnosed on ultrasound.

Baker’s cysts are an extension of the synovial compartment of the knee and are commonly seen in knees with chronic inflammation such as osteoarthritis. By definition, they communicate with the joint via a thin neck located between the semimembranosus and the medial head of the gastrocnemius.

The long term benefit of ultrasound-guided aspiration +/- cortisone injection for Baker’s cysts is controversial, although it is very safely performed and can be an effective treatment for symptomatic Baker’s cysts in the short term. Other cysts in the popliteal fossa that are not located in the characteristic location for Baker’s cysts are ganglion cysts and do not communicate with the knee joint. Ultrasound-guided aspiration +/- cortisone injection is a safe and effective treatment for ganglion cysts of the popliteal fossa, similar to ganglion cysts elsewhere in the body.

Case 95 Osteitis Pubis

A 43-year-old male presents with groin pain related to playing soccer.

Osteitis pubis is part of a spectrum of injuries that can result in groin pain or athletic pubalgia. Athletic pubalgia, the definition of which overlaps with "sports hernia," is common with sports that involve excessive twisting and shear-type stress at the pubic symphysis, such as soccer, ice hockey, and Australian-rules football. Osteitis pubis is thought to be a result of microinstability at the pubic symphysis, and subchondral irregularity and bone marrow edema are hallmarks on MRI.

Treatment for osteitis pubis and other sources of athletic pubalgia include rest and strengthening of the surrounding core muscles. Long-term role of cortisone injection is uncertain; however, it can provide therapeutic relief in patients who have not adequately recovered after other modes of therapy.

Although pubic symphyseal injection can be performed under fluoroscopy or even CT guidance, ultrasound guidance is fast, avoids radiation exposure, and is safe when done by experienced hands.

Case 94 Peripheral Nerve Sheath Tumor

A 67-year-old male presents with progressively worsening right knee pain in one pinpoint location.

Peripheral nerve sheath tumors (PNST) develop from nerve sheaths external to the central nervous system. PNSTs are predominantly benign; however, large tumors and those associated with neurofibromatosis 1 can demonstrate malignant transformation.

Benign PNSTs include schwannoma, neurofibroma (localized, diffuse cutaneous and plexiform), perineuroma and hybrid nerve sheath tumors. Patients typically present with a painful soft tissue mass and may demonstrate associated focal neurologic symptoms. On examination, a firm, non-compressible, painful lesion is appreciated.

Case 93 Avulsion fracture of the superior pole of the patella and partial rupture of the quadriceps tendon

51-year-old male with pain and weakness in extending the knee after acute sports injury.

Quadriceps injury can manifest as either a partial or complete rupture of the tendon or as an avulsion fracture of the superior pole of the patella, where the quadriceps inserts. Injury usually occurs due to rapid contraction of the muscle while the knee is flexed.

Ultrasound is a useful imaging modality for assessing these patients, and its quicker exam time, cost-effectiveness, and lack of contraindications are advantages of ultrasound compared to MRI. Ultrasound can assess the extent of tendon involvement (partial vs complete rupture) and for the presence of an avulsion fracture.

Case 92 Retained Metallic Foreign Body

63-year-old male with painful mass of the index finger.

Ultrasound is an ideal modality to evaluate soft tissue masses of the extremities. A retained foreign body can be a source of a palpable mass, and ultrasound can easily identify foreign bodies and differentiate them from other masses.

Most foreign bodies are bright on ultrasound regardless of the type of foreign body. A very bright and linear foreign body may be either metal or glass. An X-ray may be required to confirm the type of retained foreign body.

Ultrasound is also good for assessing any accompanying complications associated with the retained foreign body. Granulomatous reaction, abscess, tendon tear, and septic arthritis or tenosynovitis are potential complications of a retained foreign body.

Case 91 Complete tear of the left Achilles tendon

A 75-year-old male presents with bilateral, left greater than right, ankle pain and swelling for 1 week following the completion of a 10 day course of Levaquin for a diarrheal illness acquired in India.

Achilles tendon ruptures are typically related to sports trauma, rapid plantar flexion or forceful dorsiflexion of a plantar flexed foot. Patients frequently present with an audible pop with associated posterior ankle pain and swelling, weakened plantar flexion and more pronounced passive dorsiflexion.

Predisposing factors include middle aged “weekend warriors”, repeated microtrauma, diabetes mellitus, inflammatory conditions, intratendinous steroid injections, and fluoroquinolone antibiotic use. Ruptures commonly occur in the critical zone, a relatively hypovascular region approximately 4-6 cm proximal to the calcaneal insertion.

Case 90 Nerve sheath tumor of the tibial nerve

46-year-old female with tingling of all the toes.

Nerve sheath tumors are soft tissue neoplasms, typically benign, that are made up of variable degrees of Schwann cells, fibroblasts, and collagen. The two most common forms of nerve sheath tumors are neurofibromasand schwannomas, and they are histologically benign although they can demonstrate growth over time. Patients may present with a slowly growing palpable mass or with symptoms related to the involved nerve. If the involved nerve is in the extremity, ultrasound is an ideal modality for assessing these neoplasms.

On ultrasound, a nerve sheath tumor is identified as a hypoechoic mass arising within and enlarging a nerve, and containing internal vascularity. Distinguishing neurofibromasfrom schwannomas is not possible on ultrasound. On MRI, a nerve sheath tumor manifests as an enhancing solid mass within a nerve, and certain imaging features and enhancement patterns may suggest the particular type of nerve sheath tumor.

Case 89 Re-tear of previously repaired subscapularis tendon

70-year-old female with pain and poor range of motion 4 months after rotator cuff repair.

Ultrasound is an ideal modality for evaluating the rotator cuff tendons of the shoulder, with accuracy comparable to that of MRI according to many published reports. The integrity of each of the four rotator cuff tendons is confirmed if a robust tendon is seen attaching to the greater or lesser tuberosities of the humerus on ultrasound. In a full-thickness cuff tear, fluid is commonly seen replacing where a normal tendon is usually located.

In a shoulder with a previously repaired rotator cuff, suture anchor marking where the tendon was repaired is usually visible on ultrasound. If there are no tendinous fibers attached to the suture anchor (i.e. a bare suture anchor), this is indicative of a re-tear. Ultrasound is also the preferred modality under which an arthrocentesis is performed if there is concern that the rotator cuff re-tear is a result of an infection.

Case 88 Flexor digitorumsuperficialis tendon transection

A 55-year-old left-handed woman presents with a left index finger laceration sustained while pitting an avocado.

Penetrating injury to the palmar aspect of the finger most frequently results from knife wounds or broken glass. Open lesions may lead to injury of several flexor tendons and may be associated with concomitant vascular and/or nervous injury. Injury to the flexor digitorumsuperficialis(FDS) tendon is more common than injury to the flexor digitorumprofundus(FDP) tendon due to the more vulnerable superficial location of the FDS.

Flexor tendon injuries are categorized into five topographic zones:

  • Zone I: From the distal insertion of the FDP on the distal phalanx to the distal insertion of the FDS on the middle phalanx
  • Zone II: From the distal insertion of the FDS to the A1 pulley
  • Zone III: From the A1 pulley to the distal aspect of the carpal tunnel
  • Zone IV: Comprised of the flexor tendons within the carpal tunnel
  • Zone V: From the proximal aspect of the carpal tunnel to the flexor tendon musculotendinous junction

Lacerations usually affect the mid-substance of the tendon as opposed to its insertion site. Zone II lacerations occur most frequently and are associated with a high rate of adhesions, as well as tendon entrapment or triggering. Zone III, IV and V lacerations tend to also involve the adjacent neurovascular structures and lumbricalmuscles. Sonographic findings indicative of flexor tendon injury include focal disruption of the fibrillartendon, unsynchronized movement of the torn proximal and distal tendon stumps with dynamic maneuvers, as well as associated tenosynovialeffusion. Dynamic ultrasound can help increase the conspicuity of a complete tendon tear, determine the size of the tendon gap and indicate the amount of tendon retraction.

Ultrasound may also be utilized to detect concomitant interdigital nerve injury, which may be evidenced by focal nerve interruption acutely or hypoechoic fusiform thickening/neuroma formation in the more subacute-chronic phase of injury. Early diagnosis of tendon injury is crucial, as sonographic evaluation, as well as tendon repair, become more challenging following the development of adhesions and fibrosis, which may occur within one to two weeks of the injury. Complete lacerations necessitate surgical intervention, while partial tendon tears can be treated conservatively.

Case 87 Plantar Fasciitis with tear

74-year-old female with heel pain for several months.

Formerly believed to be a chronic inflammatory condition, plantar fasciitis is now considered a degenerative process involving the plantar fascial origin at the medial tubercle of the calcaneus. Risk factors for plantar fasciitis with or without tears include anatomic factors such as pes planus, pes cavus, excessive femoral anteversion, and increased body weight, as well as certain activities, particularly running. Patients present with long-standing heel pain with or without more acute symptoms if there is a superimposed fascial tear.

In terms of imaging, both MRI and ultrasound can identify fasciitis as an area of thickening and increased signal (MRI) or diminished echogenicity (Ultrasound), usually involving the medial fibers at the calcaneal origin. A tear would manifest as an abnormal linear cleft usually at the calcaneal origin or immediately distal to the calcaneus. Treatment includes NSAIDS, orthotics, stretching exercises and percutaneous procedures such as injection of cortisone or platelet-rich plasma (PRP). If conservative treatment fails, surgical fasciotomy is also a treatment option.

Case 86 Gout

56-year-old male with known osteoarthritis of the metatarsophalangeal (MTP) joint of the great toe presented with acute pain and swelling over the medial side of the great toe.

Gout is a crystal deposition disease in which tophi made up of monosodium urate form in soft tissues, including within joints, and incite an inflammatory arthritis. Elevation of serum uric acid is suggestive, but a definitive diagnosis requires the identification of negatively birefringent monosodium urate crystals in the affected site.

Ultrasound is a cost-effective imaging modality for assessing a joint that could potentially be affected by an inflammatory arthritis. Ultrasound also has the advantage of allowing guided arthrocentesis.

Case 85 No left lower extremity deep venous thrombosis. Thrombosed popliteal artery aneurysm.

A 71-year-old male presents with fullness in the left popliteal fossa and some pain with walking.

Aneurysmal dilatation of the popliteal artery is defined as an arterial diameter > 1.5 x the normal popliteal artery diameter, which ranges from 0.7-1.1 cm. Most popliteal artery aneurysms (PAAs) are categorized as true aneurysms, as they are comprised of all three blood vessel wall layers, the intima, media and adventitia. True PAAs are the most prevalent peripheral artery aneurysm. Risk factors associated with PAAs include advanced age, male gender, atherosclerosis, hypertension, and smoking. An increased incidence of concomitant aneurysms is seen with PAAs, and it is thus imperative to screen for coexisting abdominal aortic and contralateral PAAs.

Many patients with PAAs are asymptomatic; however, symptoms related to PAAs include lower extremity claudication, rest pain or ischemia, which may result from thrombosis or distal embolization. Ultrasound is the imaging modality of choice to diagnose PAAs and can assess for aneurysm patency and thrombus burden. Early diagnosis of PAAs is essential, as they have the potential to result in thrombosis, distal embolization and may even rupture. PAAs > 2 cm, even when asymptomatic, as well as those < 2 cm with substantial associated thrombus are typically repaired either via an endovascular or open approach, due to the high incidence of associated complications.

Case 84 Congenital patellar dislocation

7-month-old boy with congenital flexion contracture of the left knee. Clinical concern was for congenital patellar dislocation.

Congenital patellar dislocation is a rare condition in which the infant or toddler may present with a flexion contracture of the knee, genu valgum, or delayed walking. Although it may occur in isolation, there is an increased incidence of syndromic associations, including Larson syndrome, nail-patella syndrome, Down syndrome, and Ellis-van Creveld syndrome. Because the patella does not begin to ossify until 3-4 years of age, congenital patellar dislocation cannot be confidently diagnosed on radiographs. MRI and CT scan can diagnose this entity, although the former is expensive and may require sedation, while the latter involves ionizing radiation.

Ultrasound can identify both ossified bones as well as bones that are not yet ossified, making it a quick and accurate exam for evaluating many osseous structures in infants. Identifying the position of the unossified patella with respect to the femoral trochlea can easily diagnose or exclude patellar dislocation. Dynamic maneuvers performed concurrently can assess whether the patellar dislocation, if present, is fixed or reducible. Treatment of congenital patellar dislocation is surgical, as there is a high risk of permanent deformity and early osteoarthritis if left untreated.

Case 83 Rotator cuff calcific tendonitis

51-year-old female with shoulder pain and limited range of motion for one year.

Calcium hydroxyapatite deposition into a tendon, “calcific tendonitis”, most commonly occurs in the rotator cuff of the shoulder. Calcific tendonitis progresses through various phases; within the calcific stage, the formative phase is followed by the resting phase and then the resorptive phase. The resorptive phase is the most painful phase. Diagnosis can be made using either x-ray, MRI, or ultrasound.

Ultrasound has the advantage of allowing for a guided barbotage and cortisone injection during the same visit. Barbotage can break up the calcium and may speed up the resorption of the calcium hydroxyapatite deposit. Cortisone is injected into the subacromial-subdeltoid bursa to address the bursitis. If ultrasound-guided barbotage fails to provide pain relief, surgical debridement and repair of the affected rotator cuff may be indicated.

Case 82 Flexor pollicis longus (FPL) tendon rupture superimposed on moderate to severe FPL tendinosis

62-year-old male status post right distal radius open reduction and internal fixation in 2011 presents with the inability to flex his right thumb at the interphalangeal joint after doing heavy housework two weeks prior.

Flexor tendon rupture is a relatively infrequent, yet significant complication following distal radius fracture open reduction and volar plate fixation. Patients present with worsening pain, crepitus and/or decreased finger active range of motion. Most flexor tendon ruptures take place approximately 6 months to two years following surgery.

Flexor tendon ruptures resulting from volar plating occur twice as frequently in women and 1/3 of the time present between the ages of 60 and 70; however, this may be related to the increased incidence of distal radius fractures occurring in this population as a result of osteoporosis.

Factors contributing to attrition of the flexor tendon include distal plate placement, prominence of the distal edge of the plate, protruding screw heads, insufficient coverage of the distal plate edge by the pronator quadratus, fracture site collapse, tendinopathy (i.e. steroid use) as well as tendon injury.

Treatment of flexor tendon rupture consists of hardware removal and flexor tendon repair. Possible interventions to prevent flexor tendon injury following distal radius volar plating include proper plate selection and placement, precise surgical technique, repair of the pronator quadratus muscle, and/or early hardware removal.

Case 81 Haglund syndrome

45-year-old female with progressive heel pain without history of antecedent trauma.

Haglund syndrome is a constellation of soft tissue abnormalities associated with an osseous prominence of the calcaneal tuberosity. The osseous prominence is referred to as a Haglund deformity or “pump bump”, because it is commonly associated with women’s pumps.

Soft tissue abnormalities that make up Haglund syndrome consist of insertional Achilles tendinosis, retrocalcaneal bursitis, and retroAchilles bursitis. These can be identified on either MRI or ultrasound. Ultrasound has the advantage of allowing for a guided cortisone injection during the same visit.

Cortisone injection into the retrocalcaneal bursa can be performed safely under ultrasound. Because the Haglund bump is believed to be contributory, the cortisone injection may only provide short-term relief and these patients may be candidates for surgical resection of the osseous protuberance of the calcaneal tuberosity.

Case 80 Iliopsoas Tendinosis due to impingement by acetabular cup after hip replacement

64-year-old male with progressive anterior hip pain 1 year after hip replacement.

The iliopsoas tendon is susceptible to irritation after ipsilateral hip replacement. Typical history is groin pain upon walking up and down stairs and getting out of a car. Iliopsoas tendinosis with or without iliopsoas bursal distension may be seen on ultrasound.

The advantage of ultrasound is that direct impingement of the iliopsoas tendon by the acetabular cup may be visible; on MRI, susceptibility artifact from the metal can make evaluation of this area challenging.

Ultrasound-guided injection of anesthetic and cortisone can be performed for diagnostic and therapeutic purposes. Under ultrasound, the needle can be placed safely adjacent to the iliopsoas tendon and iliopsoas bursal injection can be easily performed.

Case 79 Right Rib Osteochondroma

3 year-old-girl with a painless lump at the anterior right chest.

Osteochondroma is the most common benign tumor of bone. Common sites of involvement are the long bones in the lower and upper extremity, favoring the metaphysis. Much less commonly, they can be seen in the hands and feet, the pelvis, and the scapula. Spine and rib involvement is rare.

The hallmark of this lesion on imaging is cortical and medullary continuity with the parent bone. The overlying hyaline cartilage cap is well visualized and accurately measured using US, appearing hypoechoic (dark). Osteochondromas are usually asymptomatic, presenting as a painless, hard and slow-growing lump. After skeletal maturity, these lesions cease to grow.

Although uncommon, complications related to this lesion are largely due to mass effect on adjacent structures, e.g. nerve or vascular impingement, bursal formation. The risk of malignant transformation of solitary osteochondroma is approximately 1%. A thickened cartilage cap > 2 cm is strongly suspicious for malignancy.

Case 78 Distal biceps rupture with tendon retraction

30-year-old male with acute right elbow pain and weakness flexing the elbow during weight lifting. Clinical concern was for a distal biceps tear. Ultrasound evaluation of the biceps was requested.

Discussion: Biceps rupture is an uncommon injury, usually occurring at its insertion on the radial tuberosity of the proximal radius. Patients present with weakness of elbow flexion and forearm supination after hearing a pop in the elbow. Significant proximal retraction of the tendon stump implies an injury to the biceps aponeurosis.

Diagnosis is usually made clinically, and MRI can confirm the diagnosis. Ultrasound, a quicker and more tolerated exam than MRI, can also identify biceps ruptures and assess the degree of tendon retraction. Surgery is recommended in most cases of distal biceps ruptures.

Case 77 Painful Os trigonum

25-year-old female with intermittent posterior ankle pain. MRI showed the presence of an os trigonum, but without bone marrow edema. Ultrasound-guided anesthetic injection of the os trigonum was requested to assess whether it was a symptom generator.

Discussion: Os trigonum is a fragment of bone of the lateral tubercle of the posterior process of the talus that has failed to fuse with the remainder of the talus. The incidence is said to be 7% of the population. Although it may be an incidental finding, it can be the source of pain in individuals who do activities requiring repetitive plantarflexion of the ankle, such as ballet dancers or soccer players. A painful os trigonum is often called "os trigonum syndrome", and it is one of a few conditions that can result in posterior ankle impingement.

Radiological studies play a pivotal role in evaluating patients with clinical symptoms of posterior ankle impingement.

MRI can identify an os trigonum as well as the extent of soft tissue involvement such as synovial scarring and FHL tenosynovitis. On MRI, bone marrow edema (high signal intensity on inversion recovery sequences) in the os trigonum and posterior process of talus are suggestive of a symptomatic os trigonum, but it is not 100% sensitive.

Ultrasound can also identify an os trigonum, but more importantly, it can be used to guide needle placement for a targeted injection of anesthetic with or without cortisone. If the patient feels symptomatic relief after injection of anesthetic around the os, it can increase the diagnostic confidence of the foot and ankle specialist that the os trigonum is the symptom generator.

Case 76 Flexor carpi radialis tenosynovitis

76-year-old woman with right wrist pain and palpable mass at the volar radial wrist. The patient was referred for a wrist ultrasound to assess for a ganglion cyst.

Discussion: The flexor carpi radialis (FCR) tendon has a complex insertion at the wrist, with the majority of the tendon (80%) inserting at the base of the 2nd metacarpal. 20% of the tendon insert on the 3rd metacarpal, and a few tendon slips attach to the trapezium.
The FCR tendon is encased in a sheath from the musculotendinous junction to the trapezium, and it is outside the carpal tunnel. When the tendon sheath is distended with fluid, this is called tenosynovitis.

FCR tenosynovitis is generally associated with two main conditions:

  • Overuse: Manual labor, golf or racquet sports
  • Arthritis: Radiocarpal or basilar joint arthritis

Post-traumatic FCR tenosynovitis can also be seen after a scaphoid or distal radius fracture.

Treatment is usually non-operative and includes immobilization, non-steroidal anti-inflammatory medication (NSAIDs) and peritendinous corticosteroid injection. Ultrasound guidance is ideal for safe and accurate FCR peritendinous corticosteroid injection.

Case 75 Biceps long head tenosynovitis with loose body in the tendon sheath

68-year-old female with progressively worsening left anterior shoulder pain.

Discussion: The biceps tendon long head is a common source of anterior shoulder pain.Usually due to repetitive overuse, the biceps tendon can undergo various pathologies, including tendinosis, tenosynovitis, split tears, dislocations, and ruptures. All of these conditions can be accurately assessed on ultrasound. Cortisone injection into the biceps tendon sheath is a percutaneous treatment option for anterior shoulder pain due to the biceps tendon long head.Under ultrasound guidance, the position of the needle with respect to the target can be visualized in real time so that tendon sheath injection can be performed accurately and puncturing adjacent structures such as vessels, the subscapularis tendon, or the biceps tendon long head itself can be avoided.Ultrasound also allows the radiologist to identify and address unexpected findings, such as soft tissue masses and fluid collections.

Case 74 Parameniscal cyst of the knee

22-year-old female with progressive lateral knee pain after prior ACL reconstruction and lateral meniscal repair. MRI showed a large multilobulated lateral parameniscal cyst.

Discussion: Parameniscal cyst is a ganglion cyst arising from the meniscus due to a chronic tear of the meniscus. Fluid leaks out from the meniscal tear into the extraarticular soft tissues and becomes confined by a pseudocapsule. As the cyst slowly enlarges, it can become symptomatic as it causes mass effect on surrounding soft tissues. Definitive treatment for parameniscal cysts is to surgically treat the underlying meniscal tear. A non-invasive percutaneous treatment option is aspiration and fenestration under ultrasound guidance. Performing the procedure under ultrasound allows the radiologist to directly visualize the cyst, needle, and relevant soft tissues including the popliteal artery in the current case. Cortisone is often injected at the end of the procedure, although the extra benefit of cortisone in preventing recurrence of parameniscal as well as ganglion cysts in general is controversial.

Case 73 Chronic left superior peroneal retinaculum rupture and anterior subluxation of the peroneus brevis tendon

38-year-old man with chronic left posterior lateral ankle pain and snapping sensation.

Discussion: The superior peroneal retinaculum (SPR) extends from the lateral periosteum of the lateral malleolus and attaches posteriorly on the Achilles and/or calcaneus.A normal SPR acts to keep the peroneal tendons in place within the peroneal groove at the posterior aspect of the lateral malleolus.A chronically torn SPR can result in recurrent peroneal tendon subluxation or dislocation, presenting as painful lateral ankle snapping or popping usually when walking up or down stairs.Ultrasound can efficiently evaluate for peroneal tendon subluxation or dislocation using real-time and dynamic imaging.Conservative management involves cast immobilization. If symptoms persist, surgical repair is highly successful.

Case 72 Lipoma of the antecubital fossa of the elbow

50-year-old female with slowly-growing palpable mass along the antecubital fossa of the elbow. An ultrasound was requested to rule out a soft tissue mass.

Discussion: Soft tissue lipomas are benign tumors composed of mature adipocytes that usually present as an incidental soft palpable mass.Although they are benign, they may require imaging to confirm that it is a lipoma and not an aggressive neoplasm.MRI is the most accurate modality for characterizing fat-containing tumors that are located in the deep soft tissues.For superficial lesions, ultrasound is also an accurate modality for confirming that a palpable mass is indeed a lipoma. Compared to MRI, ultrasound is more cost effective, faster, and better tolerated by patients.

Case 71 Stenosing FHL tenosynovitis

26-year-old female ballet dancer with left posterior ankle pain and difficulty dancing en pointe.

Discussion: The FHL tendon, because of its function to plantarflex the great toe and because of its particular course along the posterior ankle, is susceptible to irritation particularly in ballet dancers. Chronic irritation of the tendon can result in both tendinosis and tenosynovitis of the FHL posterior to the ankle. Like all tendons in the foot and ankle, because the FHL courses relatively superficially in the soft tissues, it is a structure that is optimally evaluated by ultrasound. Stenosing tenosynovitis, in which hypertrophic scarring of the tendon sheath can have a constricting effect on the tendon, can result in pain and diminished excursion of the FHL.

Case 70 Partial thickness laceration injury of the palmaris longus tendon

35-year-old woman with laceration injury to the volar wrist and paresthesias with palpation of the laceration.

Discussion: The palmaris longus is variably absent in between 5%-27% of the patient population. When present, the palmaris longus tendon can be found as a long and flat tendon at the volar wrist, coursing over then inserting on the central flexor retinaculum. Its superficial location makes it particularly susceptible to laceration injury. The palmaris longus tendon is a common source of tendon graft given its length and lack of functional deficit with harvest. Given its close proximity to the median nerve, injury or irritation to the palmaris longus tendon may cause paresthesias and the median nerve should be closely evaluated for concomitant injury. When harvesting the palmaris longus tendon, nerve stimulation is performed to confirm the median nerve is left intact.

Case 69 Quadriceps tendon rupture

53-year-old male with hyperflexion injury to the knee 6 days prior.

Discussion: Quadriceps tendon rupture usually occurs during rapid contraction of the muscle while the knee is flexed. Ultrasound is a useful imaging modality for diagnosing acute quadriceps ruptures, and its quicker exam time, cost-effectiveness, and lack of contraindications are advantages of ultrasound compared to MRI.
In the acute phase, fluid associated with the injury will outline the torn tendon and increase the conspicuity of the tear. In the chronic phase, the tear is often harder to detect due to the presence of scar tissue that may appear similar to tendon.

Case 68 Muscle herniation of the anterior tibialis muscle

35-year-old male with painful swelling over the anterior shin during exercise, noticed several months prior.

Discussion: Focal herniation of muscle through a defect of the fascia can be symptomatic, causing either a palpable lump beneath the skin or vague compartment-syndrome-like pain. Onset of symptoms upon exercise is classic. Ultrasound allows direct visualization of the herniating muscle, which can usually be elicited upon active muscle contraction by the patient. Because of this dynamic component to the evaluation, ultrasound is the best modality for diagnosing this entity; MRI, because it is a static exam, may not be able to identify the herniating muscle.

Case 67 Anconeus epitrochlearis muscle (accessory anconeus muscle)

42-year-old woman with numbness in the left fourth and fifth fingers. The patient was referred for an ultrasound (US) of the elbow to assess for ulnar nerve pathology.

Discussion: The anconeus epitrochlearis is an accessory muscle which originates from the olecranon and inserts on the medial epicondyle.This accessory muscle at the elbow may be asymptomatic but has been implicated as a cause of cubital tunnel syndrome which leads to ulnar neuritis. The anconeus epitrochlearis may be unilateral or bilateral. The anconeus epitrochlearis, also known as the accessory anconeus, is not to be confused with the anconeus muscle which is found at the lateral aspect of the elbow.

Case 66 Pedunculated osteochondroma of the distal femur

14-year-old girl with history of hard palpable mass along the anterior thigh, which was first noticed several months prior.

Discussion: Osteochondromas are benign cartilaginous tumors that manifest as bony excrescences with a cartilage cap, most commonly occurring around the knee. Treatment is usually conservative, although surgical resection may be considered in symptomatic patients, as in our patient. Intraoperative radiographs show the osteochondroma in our patient before (a) and after (b) surgical excision.

Case 65 Complete laceration of the flexor digitorum profundus and superficialis tendons with a tendinous gap

39-year-old female with inability to flex either the proximal or distal interphalangeal joints of the left pinky after finger laceration with a glass.

Discussion: Penetrating injuries such as accidental lacerations from a glass or knife are relatively common in the wrists and hands, and the laceration can cause a tendon tear if deep enough. The superficial location of these tendons and relative thinness of the overlying soft tissues make ultrasound a quick and ideal modality for assessing the integrity of these tendons.

Case 64 A4 pulley rupture of the right ring finger

30-year-old woman with pain in the right middle and ring fingers following rock-climbing injury. The patient was referred for an ultrasound (US) to assess for tendon injury.

Discussion: There are 5 pulleys associated with the flexor tendon sheath of the finger. The most important for biomechanical function are the A2 and A4 pulleys. The A2 is the strongest pulley but most commonly injured. Pulley rupture is an overuse injury commonly seen in rock-climbers. Sonography is effective in the evaluation of pulley rupture and can be useful to assess for the integrity of the flexor tendon.

Case 63 SPN stump neuroma due to latrogenic nerve transection

39-year-old man with history of prior ORIF of tibial fracture and multiple subsequent surgeries including fasciotomy.

Discussion: One of the complications of a nerve transection, either post-traumatic (eg. due to penetrating injury) or deliberate (as part of limb amputation) is the development of a stump neuroma. Stump neuroma can result in pain and parasthesia in the distribution of that nerve. Ultrasound can be a very accurate modality for evaluating the integrity of nerves, particularly nerves that course superficially in the extremities.

On ultrasound, a stump neuroma manifests as a heterogenous soft tissue/scar at the end of a transected nerve. As in this case, ultrasound-guided injection of anesthetic around the nerve and the scar can be helpful for confirming that the patient's symptoms are related to the stump neuroma.

Case 62 Impingement of the FHL tendon

Impingement of the FHL tendon by the proud tip of distal tibial screw causing irritation and tenosynovitis of the tendon.

Discussion: MRI and ultrasound play complementary roles in assessing for complications after surgery. Because of the outstanding soft tissue contrast and overall spatial resolution, an MRI is usually a good first line test in detecting complications such as infection, synovitis, and tenosynovitis. Ultrasound is valuable for evaluating soft tissues, and when evaluating the positioning of hardware in relation to anatomic structures, ultrasound is not susceptible to metal artifact to the same degree that MRI is. In addition, dynamic maneuvers on ultrasound may reveal information such as tendon subluxation or soft tissue herniation that static exams such as MRI will not detect.

Case 61  Right hip joint synovitis

Hip joint synovitis is a common cause of hip pain and limping in the pediatric population.

Radiographic evaluation usually shows no abnormality.

Sonography is useful to determine the presence or absence of a joint effusion.

The benefits of sonography include the ability to evaluate the contralateral side and the lack of ionizing radiation, particularly advantageous in the pediatric population.

Case 60 Glomus tumor

45-year old female with pain in the fingertip of the middle finger.

The patient did not want an MRI due to claustrophobia, thus an ultrasound was requested.

Case 59 Gamekeeper's thumb

Gamekeeper's thumb (or skier's thumb) describes a UCL avulsion fracture or rupture, usually off the base of the first proximal phalanx.

These injuries at the ulnar aspect of the 1st MCP joint may lead to significant instability, at times requiring surgical intervention.

As the structures about the 1st MCP joint are superficial, ultrasound is a useful and efficient modality to assess for the integrity of ligamentous structures following trauma to the thumb.

Case 58 Plantar fibromatosis.

Plantar fibromatosis, also known as Ledderhose disease, is the development of fibrous nodules, often multiple, in the plantar fascia. It can co-exist with palmar fibromatosis (Dupuytren’s contracture).

Case 57 Arterial pseudoaneurysm after knee replacement.

Pseudoaneurysm is an uncommon complication after total knee arthroplasty, with a reported incidence of 0.03% to 0.2%.
Symptoms of a pseudoaneurysm include pain, gait disability, cold foot, pulsatile mass and recurrent hemarthrosis.
Ultrasound is a cheap, sensitive modality for patients suspected of a pseudoaneurysm.
If a pseudoaneurysm is detected by ultrasound, MRA may be indicated to more accurately delineate the parent artery for possible embolization.

Case 56 Common peroneal nerve scar encasement.

Trauma is the most common cause of acquired peripheral neuropathy, occurring as either direct injury to the nerve (e.g. laceration, contusion) or indirect injury (e.g. scar encasement, entrapment).

Peripheral nerves have a characteristic appearance on US which helps in their identification.

Scar tissue usually appears as hypoechoic/dark tissue on US, and can cause encasement or entrapment of adjacent nerves.

US is useful in the evaluation of peripheral nerves, particularly when there is adjacent metallic hardware that can limit MRI evaluation.

Case 55 Diagnosis: Birth-related clavicle fracture

The clavicle is the most common site of birth-related fracture, reported to occur in up to 1% of vaginal deliveries.
Risk factors for fracture of the clavicle include large size of the baby, forceps delivery, and shoulder dystocia.
Although easily diagnosed by radiographs, ultrasound is an ideal alternative as it is fast, accessible, and most importantly, lacks ionizing radiation.
Additional value of ultrasound is that it can evaluate the soft tissues surrounding the clavicle should the patient’s palpable abnormality be caused by an entity other than a clavicle fracture.

Case 54 Diagnosis: DeQuervain’s tenosynovitis

Painful inflammation of the abductor pollicis longus and extensor pollicis brevis tendons. Most common in women and often in the 30-50 year age group Tendon tears are relatively uncommon. Associated with repetitive activities such as racquet sports, golf, manual labor and frequently lifting and holding a newborn child (as in the case presented). May also be associated with conditions such as rheumatoid arthritis. Treatment options include NSAIDs, physical therapy, reduction in the activities causing pain, and cortisone injections. Cortisone injections should be done with ultrasound guidance to confirm accuracy. Severe cases without response to more conservative measures may require surgery.

Case 53 Diagnosis: Peri-patellar bursitis:

Involves inflammation of the synovial-lined bursa between the skin and the patella or the patellar tendon. Common condition, often related to repetitive kneeling (carpenters, maids, gardeners, etc.) Also associated with gout, rheumatoid arthritis, diabetes, uremia, etc. With any clinical suspicion for infection, ultrasound-guided aspiration should be performed.

Case 52 Diagnosis: Metatarsal stress fracture:

Radiographs remain the initial diagnostic study of choice in evaluating for a metatarsal fracture. If radiographs are normal but the diagnosis is still suspected, MRI is the gold standard. In patients who cannot have an MRI and in other selected circumstances, an ultrasound of the area may confirm the presence of a fracture. However, if the ultrasound imaging is normal, fracture cannot be excluded and further imaging and follow-up is necessary.

Case 51 Primary synovial chondromatosis

The core biopsy samples obtained demonstrated findings compatible with primary synovial chondromatosis. This is a relatively rare condition with proliferation of islands of irregularly hypercellular cartilage seen microscopically.

Most commonly seen in the knee, this process may arise from joint synovium or less likely a tendon sheath. The condition is twice as common in men and in the primary form has no known precipitating factors.

Case 50 Bicipitoradial Bursitis

Bicipitoradial bursitis is a relatively uncommon condition resulting in inflammation and distention of the bicipitoradial bursa. This enlarged bursa may impinge upon the adjacent radial nerve bifurcation and posterior interosseous nerve.

Bicipitoradial bursitis is most commonly secondary to repetitive activity and may be associated with biceps tendon tears or tendinosis. In rare cases, the bursa may be infected and require antibiotic therapy and possible surgical intervention.

As demonstrated in this case, ultrasound is valuable in evaluating the distal biceps tendon for tear/tendinosis and in confirming the presence of an enlarged and inflamed bursa. Also, ultrasound allows safe needle aspiration and injection of the bursa as indicated.

Case 49 Intramuscular lipoma of the vastus lateralis muscle

Microscopic pathologic review of the core specimens obtained demonstrated Adipose tissue containing small bands of bland fibrous tissue and numerous skeletal muscle fibers. No evidence of mineralization.

Case 48 Plantar foot abscess following puncture injury

Costal cartilage fractures may be a difficult clinical diagnosis.

Gram stain with culture and sensitivity of the fluid obtained from aspiration yielded gram-positive cocci (Staph Aureus).

Case 47 Costochondral junction fracture

Costal cartilage fractures may be a difficult clinical diagnosis.

Radiographs are generally normal in the absence of an associated rib fracture.

While, as demonstrated, the diagnosis may be made by either CT or ultrasound imaging (as well as MRI), ultrasound is less expensive, faster, and like MRI avoids the use of radiation.

Case 46 Ganglion cyst

Ganglion cyst extending from the tibial tunnel into the adjacent soft tissues in the setting of prior ACL reconstruction.

MRI is the examination of choice in evaluating the integrity of the ACL in the setting of prior reconstruction and easily demonstrates the presence of ganglion cysts

Ultrasound may be used to confirm the diagnosis and more importantly to guide the safe and complete aspiration of these ganglion cysts

Ganglion cyst fluid is often extremely thick, requiring the use of larger (16-18 gauge) needles for complete aspiration

As clinically indicated, the fluid may be sent for laboratory analysis to exclude the possibility of infection.

Case 45 Complete tear of the ulnar collateral ligament with avulsion

Complete tear of the ulnar collateral ligament of the thumb with avulsion

While MRI has historically been the imaging study of choice for evaluating the ulnar collateral ligament, ultrasound will often quickly make the diagnosis and should be considered when this diagnosis is suspected.

It is important that complete tears are detected early so that prompt surgical correction may be performed.

Case 44 Temporal (giant cell) arteritis

Case 43 Full-thickness tear of the anchilles tendon

Case 42 Lateral ankle sprain

Case 41 Patellar tendon rupture

The interval elevation of the patella and increased patella-tibial tubercle distance as consistant with patellar tendon rupture.

Case 40 Giant cell tumor of tendon sheath

Giant Cell Tumor of Tendon Sheath involving the extensor tendon of the 2nd digit of the hand, also referred to as localized nodular tenosynovitis. Pathologically, the tissue is identical to PVNS. Lesions contain histiocyte-like multinucleated cells and fibroblastic cells. Frequently, they contain hemosiderin deposits.

Case 39 Calcium hydroxyapatite deposition disease

Case 38 Sciatic nerve stump neuroma

Case 37 Foreign Bodies

Case 36 Paralabral cyst

Paralabral cyst extending posteriorly and impinging the sciatic nerve.

Case 35 Post-traumatic seroma

Post-traumatic seroma interposed between the medial gastrocnemius and soleus muscles following partial medial gastrocnemius tear. Ultrasound-guided seroma aspiration may allow prompt resolution of symptoms and rapid improvement in patient mobility. The use of ultrasound during these procedures allows safe and accurate needle placement and ensures complete evacuation of the fluid collection.

Case 34 Ganglion cyst

Immediately following aspiration of the ganglion cyst, the patient was able to painlessly perform the ballet maneuvers and great toe flexion that had previously elicited discomfort. As clinically indicated, cortisone injection into the ganglion could also be performed at the time of the initial cyst aspiration. Due to the relatively high recurrence rate of ganglion cysts, the patient will be monitored clinically for evidence of symptom recurrence.

Case 33 Osgood-Schlatter disease

Case 32 Mucin-secreting adenocarcinoma

Moderately differentiated mucin-secreting adenocarcinoma, consistent with a pulmonary origin. This matched the previous pathology of the patient's primary lung tumor.

Case 31 Peripheral nerve sheath tumor

Peripheral nerve sheath tumor of the ulnar nerve.

Case 30 Congenital muscular torticollis

Congenital Muscular Torticollis.

Case 29 Meralgia paresthetica

Based on the clinical presentation, the diagnosis of meralgia paresthetica was considered most likely. Ultrasound evaluation of the lateral femoral cutaneous nerve was requested with peri-neural anesthetic injection to confirm the diagnosis.

Case 28 Calcific tendinosis

Calcific tendinosis of the proximal hamstring tendons.

Case 27 Infected olecranon bursitis

Case 26 Tarsal tunnel syndrome secondary to tibial nerve compression

Tarsal tunnel syndrome secondary to tibial nerve compression from a perineural ganglion cyst.

Treatment of choice is ultrasound-guided aspiration of the cyst with resulting nerve decompression.

Case 25 Ganglion cyst

Ganglion Cyst.

Case 24 Spinoglenoid notch cyst

Spinoglenoid notch cyst causing denervation atrophy and fatty replacement of the infraspinatus muscle.

Case 23 Partial thickness tear of the proximal patellar tendon

Partial thickness tear of the proximal patellar tendon.

Case 22 Nodular Pigmented Villonodular Synovitis

Nodular Pigmented Villonodular Synovitis arising from the lateral tibiotalar joint.

Case 21 Myxomatous tumors of the soft tissues

Myxomatous tumors of the soft tissues are a heterogeneous group of lesions, both benign and malignant, that show an overproduction of mucopolysaccharide substances. Characterized by a mixture of primitive mesenchymal cells and myxomatous stroma.

Case 20 Paralabral cyst compressing the femoral nerve

Following the ultrasound-guided aspiration of the paralabral cyst compressing the femoral nerve, the patient experienced symptomatic relief of her femoral nerve symptoms.

Case 19 Calcific tendinosis

Calcific tendinosis of the long head of the rectus femoris tendon at the Anterior Inferior Iliac Spine

Case 18 Schwannoma

Case 17 Epidermoid inclusion cyst

Case 16 Giant cell tumor with ABC formation

Case 15 Sindig-Larson-Johansson syndrome

Case 14 Right rectus abdominus hypertrophy

Right rectus abdominus hypertrophy with strain common in tennis players.

Case 13 Traumatic peroneus brevis tear

Traumatic peroneus brevis tear status post ultrasound guided PRP injection with healing response.

Case 12 Glomus tumor of the terminal tuft

Case 11 Lateral epicondylitis with deep surface tear of extensor tendon

Lateral epicondylitis with deep surface tear of extensor tendon origin/lateral collateral ligament with seroma formation. Ultrasound guided seroma aspiration and platlet rich plasma injection.

Case 10 Early osteoarthritis with lateral hip impingement

Case 9 Scar encasement/neuroma formation about ulnar nerve

Case 8 Lateral femoral cutaneous nerve entrapment

Initial imaging shows hypoechoic scarring surrounding the nerve near the Iliac crest and Sartorius origin. Ultrasound guided perineural injection was Performed resulting in symptomatic relief.

Case 7 Linear calcification in anterior joint capsule

Linear calcification in anterior joint capsule producing anterior impingement and pain.

Case 6 Large foreign body granuloma

Large foreign body granuloma containing multiple foreign bodies.

Case 5 De Quervain’s tendinitis/tenosynovitis

Large tendon sheath effusion, inhomogeneity of the first dorsal compartment tendons with marked hyperemia on power Doppler imaging.

Case 4 Isolated teres minor atrophy

Isolated teres minor atrophy:

  • Atrophic muscle appears echogenic and and diminutive in size
  • Normal muscle is hypoechoic on ultrasound
  • Teres minor atrophy often due to injury of the axillary nerve as it passes through the quadrilateral space

Case 3 Peroneal tenosynovitis

Ultrasound shows fluid and nodular soft tissue surrounding the peroneal tendons giving rise to the soft tissue swelling seen on radiographs.

Case 2 Osteomylitis

Case 1 Gout

Sonographic appearances suggestive of gout. Confirmed on ultrasound guided aspiration.