An Important Mid-Term Follow-up Study on Reverse Shoulder Arthroplasty

Shoulder joint replacement surgery (also called shoulder arthroplasty) can ease pain from shoulder arthritis. Most people experience improved shoulder function after this surgery. But, certain patients are not candidates for joint replacement of the shoulder because they lack the muscle function necessary to stabilize the joint. A different type of shoulder replacement, called reverse shoulder replacement or reverse shoulder arthroplasty (RSA), is used instead.

The reverse shoulder arthroplasty (RSA) is used for several different types of problems. This study examines results of patients who had a weak or deficient rotator cuff. The rotator cuff is a group of four muscles that wrap around the shoulder to hold it in the socket. They also help move the shoulder. RSA is an option when the rotator cuff is no longer strong enough or functioning well enough to hold the shoulder in the socket. The RSA provides pain relief as well as a stable functioning shoulder.

There were 75 patients with 76 shoulders included in this study. There were twice as many women as men and all patients were between the ages of 51 and 88 years old. They have been followed yearly by surgeons at the Florida Orthopaedic Institute and Foundation for Orthopaedic Research and Education in Tampa, Florida. The first set of results was published two years after surgery. This report is of the same patients five years after the RSA procedure.

Results were measured in a variety of ways. The patients filled out surveys answering questions about their motion, pain, function, abilities, and disabilities. X-rays were taken to evaluate the implant position, look for any loose screws, and assess the condition of the bone and joint. Implant survival (no loosening, no cracks, no shifting or sinking of the implant) and implant failures were also evaluated. A failure was defined as any time the patient had to have another (revision) surgery.

Analysis of the results showed that the average length of time the implants lasted was 73.5 months (a little more than six years). Almost all implants were still in place and working well at the end of six years. Five patients had to have revision surgery because some part of the implant came loose or the bone graft used was resorbed (broken down and absorbed) by the body.

There was no sign of bone loss around the implant in any of the patients. A new development not seen in the previous study was the presence of scapular notching. This change was seen in about nine per cent of the group. Scapular notching describes a problem that occurs when the medial (inside) edge of the socket (now located at the top of the humerus) bumps up against the lateral (outside) edge of the scapula (shoulder blade) where the new round ball (glenosphere) is located. Loss of shoulder motion occurs from this type of impingement.

The surgeons concluded from this mid-term study of their RSA patients that the shoulders remained stable and the implants durable. The new development of scapular notching is concerning and all patients will continue to be followed for the next five years (total of 10 years since the first RSA surgery).