Surface replacement for shoulder arthritis: Surgery with a CAP, a special type of conservative resurfacing joint replacement that resurfaces the ball of the ball and socket joint, can lessen pain and improve function.

Edited By: Frederick A. Matsen III, M.D., Winston J. Warme, MD
Last updated Wednesday, January 09, 2008

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About the procedure

What are the technical details of shoulder replacement surgery with a cap resurfacing prosthesis for shoulder arthritis? What is actually done?

Shoulder replacement surgery  with resurfacing (CAP) prosthesis [Figure 3] for shoulder arthritis is a highly technical procedure; each step plays a critical role in the outcome. Before surgery the x-rays are used to plan the procedure [Figure 4].

After the anesthetic has been administered and the shoulder is specially prepared to minimize the risk of infection, an incision is usually made across the front of the shoulder between the deltoid and the pectoralis muscle. One tendon (that of the subscapularis) is cut to allow access to the inside of the joint and to release the limitation of external rotation [Figure 5]. With the subscapularis released, the arthritic ball is exposed [Figure 6]. The bone spurs (osteophytes) are removed [Figure 7]. The diameter and height of the ball of the shoulder (humeral head) is measured  [Figure 8]. The upper aspect of the humeral head is marked for orientation  [Figure 9]. A ‘sizer’ is then used to confirm the size of the humeral head  [Figure 10] and to mark the four quadrants  [Figure 11] using the sizer windows  [Figure 12] and a cut out guide [Figure 13]. These orienting marks guide the precise placement of a guide wire  [Figure 14].  The shaper reamer is assembled [Figure 15] and used to ream the head to fit the prosthesis precisely [Figure 16] using its triple reaming geometry [Figure 17]. A trial resurfacing (CAP) prosthesis is placed [Figure 18].  A punch is used to create the central fixation hole [Figures 19 and 20].  With the trial in place, the ball is put back into the joint [Figure 21]. Once the excellence of fit of the trial is ascertained, the definitive humeral head prosthesis is inserted [Figure 22] and driven into place [Figure 23]. The desired fit is shown in cross section [Figure 24]. The ball is placed back in the joint [Figure 25]. The figures show a case where the portion of the humeral head damaged by a condition known as avascular necrosis [Figure 26] is replaced with a resurfacing (CAP) prosthesis [Figures 27 and 28]. At the conclusion of the procedure, the subscapularis tendon is repaired [Figure 29].

If the socket is damaged by the arthritis, resurfacing of the humeral head (ball of the shoulder joint) alone may be insufficient. In such cases a humeral hemiarthroplasty with a non-prosthetic glenoid arthroplasty or a total shoulder arthroplasty may be necessary.

What is the typical anesthetic used for shoulder replacement surgery with a cap resurfacing prosthesis for shoulder arthritis?

How long does shoulder replacement surgery with a cap resurfacing prosthesis for shoulder arthritis usually take?

Surgery for Shoulder Arthritis at the University of Washington

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