Shoulder replacement is a procedure for treating the severe pain and stiffness that often result from advanced arthritis 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 shoulder is a ball and socket joint. The ball portion of the joint is called the humeral head, and is part of the humerus (upper arm bone). The socket portion is called the glenoid, and is part of the scapula (shoulder blade). The humeral head (ball) fits into the glenoid (socket) and the two bones rub together as the shoulder moves.

In a healthy shoulder joint, the surfaces of these bones where the ball and socket rub together are very smooth and covered with cartilage. Arthritis causes damage to the bone surfaces and cartilage. These damaged surfaces eventually become painful as they rub together.

The treatment options for an arthritic shoulder vary quite a bit. In many patients therapy and activity modification are appropriate. In others, surgery is preferred. The decision to proceed with shoulder replacement surgery should be made very carefully after consulting your doctor. In a shoulder replacement the damaged ball and socket are removed and replaced with a metal and plastic prosthesis. This is a typical humeral prosthesis (courtesy of Zimmer):

This metal stem and ball are inserted into the humerus either with or without cement to provide a polished “ball” for smooth, pain-free motion. In many cases, the socket will be resurfaced with plastic as well.

Based on the range of motion and stability of the implant, physical therapy begins on the first postoperative day. Sling immobilization in enforced during the early rehabilitation phase.

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.

The pre-surgical condition of the shoulder muscles and tendons play the biggest role in the patient’s outcome. Dr. Diaz advises his patients to expect the following after surgery:

At about three months after surgery, most patients are reasonably comfortable, they have no pain at rest but have yet to regain their strength.

At six months, most patients are pain-free (although weather does have an effect), and have about 75% of their motion and strength.

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 preoperative condition of the deltoid and rotator cuff.