Total Shoulder Replacement
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, and function.
The surgery involves replacing the humeral head (or joint “ball”) and the glenoid (called the “socket”). [see Fig. 1] 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 that component only.
Fig. 1: Anatomy of the shoulder area, depicting the implant after surgery.
Shoulder replacement was first performed in the U.S. in 1953. Since that time, the procedure has been refined with the use of new implant materials and design, as well as improved surgical, anesthetic, and rehabilitation techniques.
Diagnosing Candidates for Shoulder Replacement Surgery
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 and 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.
A series of standard x-rays are taken to determine the condition of the shoulder joint. A CT scan and Magnetic Resonance Imaging (MRI) 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.
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.
In addition, there are certain patients who are contraindicated (are not good candidates) for TSA. These include:
· patients whose symptoms are not sufficiently disabling
· patients experiencing loss or paralysis of both rotator cuff and deltoid muscles
· patients with active infection
· in most cases, patients with a disease of the nervous system that has affected the joint
For shoulder conditions involving the surrounding muscles and tendons, such as a torn or diseased rotator cuff or a labral tear, a minimally invasive shoulder arthroscopy procedure is usually recommended. Total shoulder replacement, however, requires open surgery.
Either regional anesthesia with interscalene block or general anesthesia is used for total shoulder replacement arthroplasty. During the operation, the patient will be sedated and unconscious, positioned in a “beach-chair” position.
There are many different types of implants that are used for 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 with 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.
While the new polyethylene socket is always cemented to the bone surrounding it, the new ball has a stem that is cemented in place only when the fitting is not exact. In most cases, new prostheses feature stems that actually promote natural bone growth into the material.
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 sections of the shoulder.
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 leaving the operating room with the arm immobilized at the side, the patient will wake up in the recovery room.
Normally, 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 postioned. Sling immobilization in enforced during the early rehabilitation phase.
“As patients begin the physical therapy program, they notice that shoulder mobility is easier, and the hard grating and grinding so typical of an arthritic shoulder is no longer there.”
The patient is permitted to use the arm for light activity beginning at approximately four weeks after surgery and unrestricted, active use of the arm may begin as early as eight weeks after surgery.
We tell patients that they can usually return to desk work within two to three weeks from the time of surgery, 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. “That’s the critical difference between shoulder replacement vs. hip and knee replacement.”
Expectations after surgery:
· At about three months after surgery, most patients are reasonably comfortable, have motion about half normal, but do notice some weakness.
· At six months, most patients are pain-free (although weather does have an effect), and have motion and strength about two-thirds normal.
· At one year, approximately 95% of TSA patients will be pain-free, and the remaining will usually have no more than a weather ache or an occasional ache with excessive activity. Likewise, there will probably not be significant strength limitations, depending on the condition of the deltoid and rotator cuff.
The most common complications involved in TSA, which occur only rarely, include shoulder stiffness, instability, 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.