Shoulder Replacement Surgery

what is shoulder replacement surgery?

Total shoulder replacement, also known as total shoulder arthroplasty, is the removal of portions of the shoulder joint, which are replaced with artificial implants to reduce pain and restore range of rotation and mobility. It is very successful for treating the severe pain and stiffness caused by end-stage arthritis.

Shoulder arthritis is a condition in which the smooth cartilage that covers of the bones of the shoulder degenerate or disintegrate. In a healthy shoulder, these cartilage surfaces permit the bones to comfortably glide against one another. When these cartilsage surfaces disappear, the bones come into direct contact, increasing friction and causing them to roughen and damage each other. Bone-on bone movement can be quite painful and difficult. Surgically implanted artificial replacement surfaces restore pain-free movement, strength and function.

Surgical steps of a traditional shoulder replacement

A traditional (anatomic) shoulder replacement surgery is composed of the following six basic steps:

1. The surgeon separates the deltoid and pectoral muscles to access the shoulder in a largely nerve-free area (to minimize nerve damage).

2. The shoulder is opened by cutting one of the front muscles of the rotator cuff, which covers the shoulder. This “opens the door” to allow the surgeon to view and manipulate the arthritic parts of the shoulder ball and socket.

3. The arthritic sections of the joint are removed.

4. The implant socket, ball and stem components are inserted. The metal ball component is attached to the stem, which extends down inside the patient’s humerus.

5. The incision of the rotator cuff muscle is closed and stitched.

6. The external (skin-level) incision is cleaned and stitched, and a bandage applied as a temporary covering.

Types of shoulder replacement implants

All shoulder replacement systems share the same basic components: a metal ball that rests against a plastic (polyethylene) socket. But their designs vary.

In anatomic shoulder replacements

The polyethylene socket in a traditional shoulder replacement 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, the design of the stem prosthesis promotes, osseointegration, in which the patient's natural bone grows into the prosthetic material.

Surgeons from Hospital for Special Surgery designed a special implant called the Comprehensive Primary Shoulder System (see Figure 4), with a cobalt-chrome or titanium ball and a titanium stem. The system's specialized ball component creates a new humeral head that conforms to the patient’s exact anatomy. The ball, stem and socket all fit together in ways that provide a more customized fit.

In reverse shoulder replacements

The components are still metal and plastic, but reversed: The metal ball is attached to the patient's existing socket, and a new plastic socket is attached to the patient's upper humerus, which formerly included the natural ball of the anatomic shoulder.

The stem is designed to be cementless to promote the ingrowth of bone into the prosthesis. The plastic socket also features a metal peg that allows the patient's natural bone to grow into the implant. The Comprehensive Reverse Shoulder System (see Figure 6), also designed by HSS surgeons, is entirely cementless. Both sides of the joint feature the ability for natural bone to grow into, and become integrated with the implant.

How long does it take to recover from a shoulder replacement?

It generally takes eight weeks or more for patients to recover. It may be several months before a patient may do heavy labor or strenuous strength exercises.

On the day of surgery

The patient will wake up in the recovery room with the arm immobilized at the side in a removable canvass arm sling. Patients usually experience some temporary pain due to the surgery, but it is not the same type of pain they experienced due to their arthritis. Arthritic pain is largely absent from that point forward.

The day after surgery

X-rays will be taken to determine whether the implant is properly positioned. After the range of motion and stability of the implant are confirmed, physical therapy will begin that same day. Patients usually notice immediately that the shoulder is easier to move and the feeling grinding is gone.

The shoulder will be immobilized by a sling during the early rehabilitation phase to permit the tendons which have been repaired to heal. This sling is removable for showering and for rehabilitation exercises. Mobility improves throughout the period of physical therapy.