Total Shoulder Endoprosthesis

Shoulder replacement surgery is a highly technical procedure; each step plays a critical role in the outcome.

After administering anesthesia, an incision is made across the front of the shoulder from the middle of the collarbone to the middle of the arm bone. This allows access to the joint without damaging the important deltoid or pectoralis muscles that are responsible for a significant portion of the shoulder's power.

Scar tissue that may be restricting the movement of the muscles and other tissues near the shoulder are removed hence increase mobility. The tendon of the subscapularis muscle is removed to gain access to the joint and released circumferentially to restore its length and mobility. The arthritic humeral head (ball of the joint) is removed and the bone spurs are removed to prepare the bone for the humeral prosthesis.

A hemiarthroplasty may be performed, if the glenoid socket is unaffected or is in other selected conditions. In a cuff tear arthropathy, a hemiarthroplasty (replacing the humeral joint surface only) is usually selected because the anatomy does not favor the use of a glenoid prosthesis. The humeral component is made of metal and is usually press fit, but sometimes cemented, into the shaft of the bone of the humerus.

If the glenoid is affected and conditions do not favor the insertion of a glenoid component, a non-prosthetic glenoid arthroplasty may be performed along with a humeral hemiarthroplasty. In this procedure, the glenoid shape and orientation are corrected without inserting a glenoid prosthesis. The prosthetic ball of the humeral component articulates with the reshaped bony socket of the glenoid. This procedure may be selected when the patient is interested in performing heavy activities that might jeopardize the fixation of a polyethylene glenoid component.

In a total shoulder joint replacement, the glenoid bone is shaped and oriented as in the non-prosthetic glenoid arthroplasty and then covered with a polyethylene glenoid component, as seen in the figure. A small amount of bone cement is used to hold the artificial glenoid socket in place.

At the conclusion of any of these procedures, the subscapularis tendon is securely repaired to the bone. This repair requires protection from active use for at least 6 weeks while it is healing.

Anesthetic A general anesthetic or a brachial plexus nerve block can be used for a shoulder joint replacement surgery. A brachial plexus block can provide anesthesia for several hours after the surgery. Preferences are discussed with the anesthesiologist before surgery.