A 59-year-old woman presented with a 3-year history of progressively worsening right buttock and groin pain radiating to her knee and requiring opioid analgesia. Born with bilateral developmental dysplasia of the hip (DDH) and congenital talipes equinovarus, the patient underwent primary right total hip arthroplasty (THA) at age 34 in 1983 and left THA in 1984. She required multiple revisions of both hips. Her most recent right THA revision in 2005 was complicated by infection requiring a 2-stage reconstruction with antibiotic spacer prior to reimplantation.
Significant medical history included hypertension, anxiety and depression, peripheral neuropathy, osteoporosis, and 30 pack-years of smoking. The patient required crutches from childhood due to DDH and a right foot drop for which she had not worn an ankle-foot orthosis. She was wheelchair dependent due to worsening pain.
Physical examination revealed multiple well-healed right hip incisions, groin and buttock pain with hip motion, and a positive log-roll test. Range of motion was from full extension to flexion, 100°; internal rotation, 30°; external rotation, 70°; abduction, 45°; and adduction, 20°. Right hip abduction power was significantly diminished (2/5). Neurovascular examination demonstrated a right foot drop with 2/5 power in the common peroneal nerve distribution. Trendelenburg and Stinchfield tests were positive. The right leg was 1 cm shorter than the left.
Baseline white blood cell count was normal, but inflammatory markers were moderately elevated (erythrocyte sedimentation rate, 47 mm/hr; C-reactive protein, 6.7 mg/L). Bilateral hip joint fluoroscopy-guided aspirations did not indicate recurrent infection. Radiographs demonstrated a hybrid right THA, with femoral stem cement mantle fracture, metal debris, and periacetabular radiolucency in all Charnley zones (Fig. 1A). Computed tomographic (CT) reconstruction revealed complex bony defects and a Paprosky IIIA acetabular defect and a Paprosky IIIA-IIIB femoral defect  (Fig. 1B). Further preoperative evaluation included 3-dimensional computer models of the pelvis to visualize bone defects and virtual removal of the existing prosthesis (Fig. 2).
Figure 1: (A) Preoperative radiograph demonstrating a hybrid right THA, with femoral stem cement mantle fracture, metallic debris, and periacetabular radiolucency in all Charnley zones. (B) CT reconstruction revealing complex bony defects and a Paprosky IIIA acetabular defect and a Paprosky IIIA/IIIB femoral defect.
Figure 2: Computer model of the pelvis showing (A) bone defects and (B) virtual removal of the existing prosthesis.
The patient underwent single-stage revision right THA. Intraoperatively, the fascia lata, iliotibial band, and hip abductor musculature were found to be grossly deficient due to previous surgery and adverse reaction to metallosis. After encountering severe anterior cortical bone loss in addition to gluteal deficiency, the surgeon decided to change from a posterior to an anterolateral approach in order to utilize the anterior bony defect as a modified Wagner osteotomy . An extended trochanteric osteotomy was required for prosthesis removal and cement extraction. Reconstruction was performed with an uncemented highly porous trabecular metal (TM) cup, superolateral TM acetabular augment, long modular tapered uncemented stem, and dual mobility articulation (Fig. 3). Results of intraoperative tissue histopathology were consistent with metallosis and polyethylene debris–induced osteolysis. Both histology and extended cultures confirmed the absence of infection.
Figure 3: (A) Postoperative radiograph showing right hip reconstruction with an uncemented highly porous TM cup, superolateral TM acetabular augment, and long modular tapered uncemented stem. (B) Intraoperative photo showing dual mobility articulation.
The patient’s wound healed well, with no sign of infection. At 3-month follow-up, she had progressed to full weight bearing with crutches, taking tramadol as needed. She had a range of motion from full extension to flexion of 100°, internal rotation of 20°, external rotation of 40°, abduction of 30°, and adduction of 10°. Follow-up radiographs demonstrated a well-fixed implant in excellent alignment, with no change in position from her immediate postoperative imaging.
Severe acetabular and femoral bone loss presents a significant challenge to the surgeon performing revision THA. Complications associated with these extensive surgeries are significantly increased in comparison to primary THA, with higher rates of dislocation (4% to 8%, respectively) and prosthetic joint infection (8% to 10%, respectively) . Numerous strategies exist to address bone deficiencies. Acetabular reconstruction options include the use of cages, cup/cage combinations, custom flange acetabular components, and acetabular augmentation with a TM prosthesis (Fig. 4).
Figure 4: (A) Custom flange acetabular components. (B) Acetabular augmentation with TM prosthesis.
Trabecular metal (tantalum) is a highly porous bioinert metal ideal for complex arthroplasty applications, providing initial stability through an extremely high co-efficient of friction. Rapid bony ingrowth and final stability is facilitated by the implant’s high surface area. A TM acetabular implant, augmented with a superior and lateral buttress, enables acetabular reconstruction providing strong mechanical support and secure biological ingrowth surface. TM augments used to treat acetabular defects have demonstrated consistent improvement in patient-reported outcome measures and a low rate of complications [3-5].
In this case, preoperative computer modelling and a 3-dimensional printed solid model gave the surgeon extensive information on the intricate pattern of bone loss and the ideal component position. Thus, the surgeon could decide how to work with very limited bone stock, particularly in the medial and posterior acetabular regions. This case demonstrates the principles integral to success in revision THA, including multidisciplinary preoperative planning, selection of a prosthesis that provides initial and long-term fixation when faced with extensive bone loss, and an ability to change the surgical approach to accommodate unexpected findings.