The videos on this page can be downloaded upon purchase of a license on Alila medical Media website. Click here!
Reverse Total Shoulder Replacement or Delta Shoulder Replacement is a modification of total shoulder replacement procedure. The conventional procedure has a metal ball on the humerus (replacing the natural humeral head) and a plastic component on the glenoid. The reverse procedure has the reverse positions of the prostheses : the metal ball is now fixed on the glenoid socket and the plastic cup is fixed in place of the humeral head (Fig. 1). This configuration is indicated for people with rotator cuff arthropathy.
Fig. 1: Configuration of conventional versus reverse total shoulder replacement. Note the location of the metal head and plastic component in each case. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.
Why a conventional total shoulder will not work with rotator cuff arthropathy?
Rotator cuff arthropathy or cuff tear arthropathy (CTA) is shoulder arthritis in a setting of rotator cuff tears. Rotator cuff muscles hold the ball and the socket together and prevent the humeral head from moving out of the socket when the deltoid muscle raises the arm. In people with torn rotator cuff, the head of the humerus moves upwards out of the socket resulting in shoulder instability. Conventional total shoulder preserving the natural configuration of the shoulder joint will encounter the same problem (Fig. 2, left panel).
Fig. 2: Conventional versus reverse total shoulder replacement with torn rotator cuff. The upward force displaces the humeral head in conventional configuration but stabilizes the joint in reverse configuration. Click on image to see a larger version on Alila Medical Media website where the image is also available for licensing.
Why a reverse total shoulder would work?
In reverse total shoulder procedure, the arthritic humeral head is replaced with a plastic cup and the metal ball is fixed onto the glenoid surface. With this configuration, the contraction of the deltoid will move the arm up and compress the socket to the ball at the same time (Fig. 2, right panel). The ball and the socket will fit more snugly together providing stability.
