Overview

Anatomic total shoulder arthroplasty is a joint replacement procedure designed to relieve pain and restore function when the shoulder joint has been permanently damaged, most commonly by advanced arthritis. Unlike arthroscopic surgery, which treats specific problems while preserving the joint surfaces, anatomic shoulder arthroplasty removes the worn joint surfaces and replaces them with artificial components that recreate the normal ball-and-socket anatomy of the shoulder.

I often compare the joint surface to a tile floor. With arthroscopy, loose pieces can be removed and rough areas can be smoothed, but new tile cannot be brought into the room. With arthroplasty, the worn surface itself is replaced - much like removing a damaged floor and installing a new one.

When Is Anatomic Shoulder Arthroplasty Recommended?

Shoulder replacement is generally considered after appropriate conservative treatment has failed to provide adequate relief. Medications, physical therapy, injections, activity modification, and selected arthroscopic procedures can often reduce symptoms and postpone the need for replacement. When arthritis progresses to the point that pain, stiffness, loss of motion, sleep disturbance, or loss of function significantly affects quality of life, anatomic shoulder arthroplasty can become a highly effective and predictable treatment option.

A functioning rotator cuff is essential for an anatomic shoulder replacement because the rotator cuff continues to stabilize and move the shoulder after surgery. If the rotator cuff is deficient or no longer functional, a reverse shoulder arthroplasty is generally required instead.

What Is Replaced?

The goal of an anatomic total shoulder arthroplasty is to reproduce the shoulder's normal anatomy. The worn glenoid, or socket, is resurfaced with a durable polyethylene component, while the damaged humeral head is replaced with a metallic prosthesis. When bone quality allows, I prefer an ultra-small, bone-preserving stemless prosthesis on the humeral side. This preserves more of the patient's native bone while still providing a stable replacement.

Goals of Surgery

The primary goals are substantial pain relief, improved motion and function, better use of the arm for daily activities, and an overall improvement in quality of life. Because the normal relationship between the ball and socket is preserved, ultimate range of motion is often better than that achieved with a reverse shoulder arthroplasty.

Planning the Operation

Every patient undergoes a preoperative CT scan. Modern shoulder replacement allows the operation to be planned in detail before entering the operating room, including implant size, position, alignment, and the relationship of the components to the patient's individual anatomy. This preparation allows the replacement to be individualized rather than approached as a one-size-fits-all operation.

Surgery and Recovery

Most patients undergo anatomic shoulder arthroplasty on an outpatient basis. During the first six weeks, patients are encouraged to use the arm for light daily activities within the "box of the body." Think of this almost as the shadow or frame of your body: if someone were standing directly behind you, they should generally not be able to see your forearm or hand extending outside the outline of your body. You can bring the hand inward toward the body and always work upward toward the head and above, but avoid reaching the arm outward away from the body. Lifting is limited to no more than a couple of pounds during this period.

6 weeks: Discontinue the sling and begin unrestricted motion with light activities.
3 months: Progress to moderate activities.
6 months: Progress toward final activities.

Although there are no absolute lifetime restrictions, I generally recommend limiting repetitive lifting to approximately 25-30 pounds to help maximize implant longevity.

Potential Complications

Modern shoulder arthroplasty is an extremely successful procedure, but potential complications include implant loosening, dislocation, stiffness, and infection.

Infection is fortunately uncommon but can be the most devastating complication following shoulder arthroplasty. These infections typically occur months or even years after the operation and are not a direct result of the surgery itself. Instead, bacteria circulating in the bloodstream can attach to the prosthesis and establish an infection around the implant. Treatment requires surgery and usually involves removal of the prosthesis, IV antibiotics, and eventual revision shoulder arthroplasty.

Fortunately, complications are uncommon, and the overwhelming majority of patients experience significant improvement in pain, function, and quality of life.