Our last blog discussed the purpose and benefit of a total shoulder replacement or arthroplasty (TSA). Today’s blog will discuss what a reverse total shoulder arthroplasty (rTSA) is and why someone might need one.
Why would someone have a reverse total shoulder replacement versus a typical TSA? This particular procedure is used for conditions including non-repairable rotator cuff damage in conjunction with arthritis, complex shoulder fractures, and revisions of failed conventional TSAs. For more information about the anatomy and function of the rotator cuff, check out our past blog on the topic here. A traditional TSA can be very beneficial for pain related to arthritis at the shoulder; but if the rotator cuff is not functioning properly, then the traditional TSA will not be effective in restoring function to the shoulder. The structure of a rTSA allows muscles other than those of the rotator cuff to assist with movement; therefore, it is a more viable option for individuals who have a non-functioning rotator cuff.
What is the structure of a rTSA? The normal anatomy of the shoulder is a ball and socket joint with the ball being the top of the humerus (upper arm bone) and the socket being the glenoid (cup like structure at the edge of the shoulder blade). A rTSA reverses the ball and socket components of the shoulder anatomy. Instead of the humerus forming the ball, an artificial metal ball is attached to the glenoid surface; and instead of the glenoid forming the socket, the head of the humerus is taken off and replaced with a plastic artificial socket. This gives the deltoid muscle (a muscle that lays overtop of the rotator cuff) a biomechanical advantage in order to lift and move the arm. If there is severe enough weakness in the muscles that rotate the shoulder outward (external rotators), then a surgeon may also perform a tendon transfer using the tendon from the latissimus dorsi muscle.
What can be expected from rehab following a rTSA? The expectations for range of motion and strength are a little different between a TSA and a rTSA. In the case of a rTSA, full motion is not expected. Even though the deltoid muscle has the ability to lift the arm, it is not capable of producing the same range of motion as when the rotator cuff muscles are intact. There is also the potential for external rotator weakness as previously discussed. If a tendon transfer is not performed to correct a severe degree of external rotation weakness, then this will also limit the mobility of the arm following surgery. Despite the limitation in full motion, satisfaction following a rTSA is typically very high.
Stay tuned for our next blog which discusses the rehab parameters for both a TSA and rTSA. We hope that this blog was informative. If you have any questions on this topic or any others in which you are interested, feel free to leave any questions, comments, or suggestions.