Reverse shoulder replacement was originally developed for patients with cuff tear arthropathy and loss of active overhead function (also known as pseudoparalysis). Cuff tear arthropathy is a type of arthritis marked by an irreparable rotator cuff tear that results in upward migration of the ball on the socket. This is shown in the figure where the ball is shifted upward in the socket due to the loss of rotator cuff function.
As the success of reverse shoulder arthroplasty has been proven over time, its indications have grown to include certain patients with primary osteoarthritis for whom the results of reverse shoulder replacement have proven more predictable with fewer complications compared to anatomic shoulder replacement. The following are five situations and reasons for this.
- Age greater than 75: beyond 75 years many patients will not be able to adequately heal repair of the subscapularis tendon which is integral for optimal function of an anatomic shoulder arthroplasty.
- Considerable glenoid erosion: arthritis can cause significant wear of the shoulder socket and this wear can compromise the bone available for implantation of a glenoid implant. The baseplate of a reverse shoulder is more forgiving of this wear than an anatomic shoulder replacement
- A history of rheumatoid arthritis: those with inflammatory arthritis are more prone to eventual rotator cuff tears and will have a more predictable results with reverse shoulder replacement
- Failed prior surgery: those who have failed prior shoulder replacement for any number of reasons will have a better outcome from revision with reverse shoulder replacement.
- Significant rotator cuff muscle atrophy: some patients with severe arthritis have advanced rotator cuff muscle atrophy and will have a protracted and uncertain recovery after anatomic shoulder replacement. When this is the case, a more rapid and predictable recovery can be achieved with a reverse replacement.