Total shoulder replacement, also known as total shoulder arthroplasty (TSA), is a tremendously successful procedure for treating the severe pain and stiffness that often result at the end stage of various forms of arthritis or degenerative joint disease of the shoulder joint. The primary goal of shoulder replacement surgery is pain relief, with a secondary benefit of restoring motion, strength, function, and assisting with returning patients to an activity level as near to normal as possible. Many patients return to the sports they love like tennis, golf, and swimming, while also pursuing personal health initiatives such as individual training, yoga and pilates.
Painful shoulder arthritis refers to the disappearing of the normally smooth cartilage surfaces of the shoulder, which permit the ball and socket to smoothly glide against one another. This disappearance of cartilage covering results in a “bone on bone” joint and can be quite painful. Thus new surfaces provide the answer for restoration of comfort.
The actual surgery involves replacing the damaged humeral head (or joint “ball”) with a metal ball, and putting a new smooth plastic surface on the glenoid (called the “socket”). [see Fig. 2] Metal on plastic surfaces (rather than metal on metal) are the hallmark of virtually all shoulder replacement implant systems. Partial shoulder replacement (or hemi-replacement) may also be indicated with certain severe shoulder fractures of the humeral head. This technique requires the replacement of the ball component only.
In recent years, a new type of shoulder replacement, the "reverse" shoulder [Figure 6] has entered the armamentarium of shoulder surgeons to treat arthritis. HSS surgeons have led the design team of both traditional, or “anatomic” shoulder replacement, and the Reverse shoulder.
The design rationale for the reverse shoulder replacement is based on the fact that since in nature the shoulder ball “rests against” the socket, rather than being deeply contained within the socket, it relies on the tendons surrounding the ball socket to both hold it in place and to move it. In some types of arthritis, these tendons are severely damaged, torn, or non functioning. Because of this, an anatomic shoulder has no soft tissue to hold it in place and or to move it.
The design of the reverse shoulder puts the ball on the patients own socket, and it is the plastic socket which is placed on the humerus bone. The reverse design has more stability and does not need the tendons to hold it in place. It also is moved by the deltoid muscle, not the rotator cuff tendon, so it is an ideal choice when the damaged shoulder needs new surfaces, but does not have healthy enough soft tissues for stabilization and movement.
HSS surgeons have been instrumental in developing new materials, designs, and techniques. Since its introduction in the United States 1/2 century ago, the procedure has been refined by combinations of improvement in surgical, anesthesia, and rehabilitation techniques.
The most common indication for TSA is shoulder pain due to arthritis that cannot be controlled with non-operative treatment such as anti-inflammatory medications by mouth or injection, or rest. Accompanying the pain is a progressive stiffness and loss of motion, with the patient often experiencing a grinding or grating sensation within the shoulder joint that is disturbing and painful. These sensations represent the bones of the ball and socket, devoid of cartilage, rubbing against one another.
A series of standard x-rays are taken to determine the condition of the shoulder joint (See Figure 1). A CT scan, which is a specialized x-ray, and Magnetic Resonance Imaging (MRI) which is not an x-ray, may also be necessary to evaluate bone quality as well as the condition of important surrounding structures such as the rotator cuff tendon. Those with possible nerve damage may also undergo an EMG test, or Nerve Conduction test, to evaluate the nerves which feed the important muscles of the shoulder.
In some chronic arthritic conditions such as ankylosing spondylitis, which may be associated with a stiff elbow and a stiff shoulder, TSA may be considered to improve overall function in the shoulder and arm, regardless of the pain level experienced by the patient.
Steroid injections are sometimes recommended prior to a TSA procedure. Most candidates, however, will not experience lasting relief from these injections, making TSA a necessary next step if pain is uncontrolled. Likewise, some patients experiencing early osteoarthritis may consider more conservative management (such as physical therapy, medication, cortisone injections, or even shoulder arthroscopy) before TSA is deemed a necessary measure. Shoulder arthroscopy, while attractive because it is minimally invasive, plays a very limited role in the shoulder with arthritis, but may be of value before the joint has truly become "bone on bone".
In addition, there are certain patients who are contraindicated (are not good candidates) for TSA. These include:
For many shoulder conditions involving the surrounding ligaments, muscles and tendons, such as a torn or diseased rotator cuff or a labral tear, a minimally invasive shoulder arthroscopy procedure is frequently recommended, and they are among the most common and frequently indicated shoulder procedures. Total shoulder replacement, however, requires open surgery, with an incision along the front of the shoulder and upper arm.
Either regional anesthesia with interscalene block or general anesthesia, frequently together, is used for total shoulder replacement arthroplasty. During the operation, the patient will be sedated and unconscious, positioned in a “beach-chair,” or sitting up, position.
There are many different types of implants that are used for an anatomic shoulder replacement. They all, however, share the same basic components: a metal ball that rests against a plastic (polyethylene) socket. The goal of shoulder replacement is to remove the patient’s arthritic humeral head, replace it with the metal “ball” component attached to a stem that extends down inside the patient’s humerus (upper arm bone), and then place a plastic socket over the surface of the patient’s own glenoid (See Figure 2).
In a reverse shoulder (See Figures 5&6), these components, while still metal and plastic, are “reversed”, the metal ball is attached to the patient socket, and the plastic socket is attached to the upper humerus.
The polyethylene socket is often cemented to the bone surrounding it, at least in part, so that fixation to the bone is immediate. The prosthetic ball has a stem that is usually placed inside the humerus without the need for cement. In most cases, new prostheses feature stems that actually promote natural bone growth into the material.
Dr. Craig and two of his colleagues at HSS, Russell F. Warren, MD, and David M. Dines, MD, have designed and utilized a new implant, The Comprehensive Primary Shoulder System, (See Figure 3) with a ball made of cobalt chrome and a stem made of titanium metal, featuring modular (separate) components; the ball, stem, and socket all fit together to provide a more customized fit. The ball component features Versadial®, which allows for the new humeral head to be “dialed in” to conform to the patient’s exact anatomy, and the stem was designed to be cementless, providing the opportunity for the ingrowth of bone into the prosthesis.
The socket also features a metal peg permitting native bone to grow into the implant. The Comprehensive Reverse Shoulder, which these surgeons have also designed, is entirely cementless, with both sides of the joint featuring the ability for native bone to grow into, and become part of, the implant.
The surgeon begins by separating the deltoid and pectoral muscles, accessing the shoulder in a largely nerve-free area to minimize nerve damage. The shoulder is covered by the rotator cuff, which must be opened by cutting one of the anterior (front) rotator cuff muscles. This “opens the door,” allowing the surgeon to view and manipulate the arthritic parts of the shoulder ball and socket.
After the arthritic sections have been removed, the surgeon inserts the implant socket, ball, and stem components, closes and stitches the rotator cuff muscle, and stitches and cleans the incision, after which a bandage is applied as a temporary covering.
After leaving the operating room with the arm immobilized at the side in a removable canvass arm sling, the patient will wake up in the recovery room.
“Normally,” notes Dr. Craig, “patients will wake up from surgery with pain due to surgery, but not the same type of pain they have experienced due to their arthritis. Arthritic pain is largely absent from that point forward.”
Based on the range of motion and stability of the implant, physical therapy begins on the first postoperative day, following x-rays documenting that the implant is properly positioned. Sling immobilization is enforced during the early rehabilitation phase to permit the tendons which have been repaired to heal. The sling is removable for showering and rehabilitation exercises.
“As patients begin the physical therapy program, they notice that shoulder mobility is easier,” Dr. Craig explains, “and the hard grating and grinding so typical of an arthritic shoulder is no longer there.”
The patient is permitted to use the hand and wrist soon after surgery, and the whole arm, including shoulder, for light activity beginning at approximately six weeks after surgery. Unrestricted, active use of the arm may begin as early as eight weeks after surgery.
“I do tell patients that they can usually return to desk work within two to three weeks from the time of surgery,” says Dr. Craig, “but that heavier work is forbidden for four months or more and depends greatly on the motion and strength of the shoulder and how they are progressing.”
The pre-surgical condition of the shoulder muscles and tendons play the biggest role in the patient’s outcome. “If their muscles and tendons are in good shape, rehab will be less burdensome as the type and rapidity of post-surgical rehabilitation of the shoulder depends on the patient’s own muscles and tendons.” Dr. Craig notes. “That’s the critical difference between shoulder replacement vs. hip and knee replacement.”
Dr. Craig advises his patients to expect the following after surgery:
The most common complications involved in TSA, which occur only rarely, include shoulder stiffness, instability (the ball slipping out of the socket), infection, nerve damage, and glenoid loosening.
An arthritic shoulder is often very tight to begin with, however if post-operative stiffness is a problem in a shoulder in which motion was restored during surgery, the stiffness is usually a result of incomplete rehabilitation. Continued rehabilitative efforts are usually effective in restoring shoulder motion and strength.
Total shoulder arthroplasty is a highly beneficial surgical procedure intended to reduce pain and restore mobility in patients with end stage shoulder arthritis, and occasionally after certain severe shoulder fractures. In most cases, non-operative measures such as medication, injections, and gentle physical therapy are considered prior to deciding on surgery.
It is important to understand that proper and extensive post-operative rehabilitation is a key factor in achieving the maximum benefit of shoulder replacement surgery. With this in mind, TSA is generally considered to be as successful in relieving pain as total hip or knee replacement.
After one year, 95% of TSA patients enjoy pain-free function, which enables them to exercise the shoulder area sufficiently to promote restoration of strength and motion. Because of this, most patients successfully return to the activities they enjoy, making the procedure a highly valued choice for a wide variety of patients suffering from significant shoulder pain due to cartilage loss.