If you’ve heard of reverse shoulder replacement, you may be concerned about the idea of having a shoulder that’s “backwards”. In this article, Dr. Sperling explains what this really means.
In traditional total shoulder replacement, also called anatomic shoulder arthroplasty, a portion of the ball (humeral head) is removed and a smooth metal ball is placed. On the socket side of the joint (glenoid), a curved plastic piece is placed. This creates two smooth surfaces intended to help improve function and relieve pain.
The challenge with anatomic shoulder replacement is that it requires a functional rotator cuff to keep the implant stable and to function effectively. Therefore, an anatomic total shoulder replacement is not typically used in patients with rotator cuff deficiency.
In 1985, a French surgeon named Paul Grammont described the use of a “reverse” shoulder replacement.1 It was indicated for use in patients who had deficiency of their rotator cuff.
In a reverse shoulder replacement, a small baseplate with screws is placed in the socket. A round sphere is then connected to the baseplate.
On the humeral side, a portion of the bone is removed. A stem is placed within the bone and then a cup shaped tray is placed. Therefore, in reverse arthroplasty, a ball is placed where the socket used to be located and a cup is placed where the ball used to be located. They are “reversed”.
The below two images are edited to illustrate the differences between the anatomic and reverse shoulder implants. In reality, the implants will not have a gap between them, but articulate with one another. The left image shows the anatomic shoulder implanted; on the right shows the reverse shoulder implanted.
The reverse arthroplasty uses the outer muscle of the arm, the deltoid, to compensate for a deficient rotator cuff. Moreover, the more constrained nature of the reverse arthroplasty provides increased stability compared to an anatomic shoulder arthroplasty. The trade-off is that with reverse arthroplasty, there may be less motion particularly with getting the hand behind the back.
With any surgical procedure, there are risks. You can read about some of the associated risks of shoulder replacement by clicking here; but also discuss these, and other, risks with your surgeon.