Shoulder replacement is the third most common joint replacement surgery after the knee and the hip. Shoulder replacement is usually required if severe arthritis is present or if the rotator cuff is torn. The shoulder joint is a ball-and-socket joint that allows for a wide range of motion. It is made up of the humerus (upper arm bone), the scapula (shoulder blade), and the acromion (bony projection of the scapula).
Interestingly there are two forms of shoulder replacements. The first is the traditional shoulder replacement which is usually termed ‘Total Shoulder Replacement’ (TSR). The other form is the Reverse Total Shoulder Replacement (RTSR) which is a newer technique. With the traditional TSR, the ball and socket are replaced with artificial components and mimic the normal anatomy of the shoulder. However, in a RTSR the ball and socket components of the joint are switched. The ball is attached to our scapula and the socket is fixed to the head of our humerus. The reverse design of the RTSA relies on the deltoid muscle, instead of the rotator cuff, to power and position the arm. This makes RTSA a good option for people with severe rotator cuff tears or arthritis that has damaged the rotator cuff.
This asks the question which one is right for you?
A study by Simovitch et al. (2017) compared the rate of improvement in patients with a traditional TSR vs RTSR. They found that patients who underwent a RTSR experienced larger improvement in pain, strength, function, and active forward flexion (lifting arm up forwards). While the patients who underwent a TSR demonstrated better improvement in general shoulder range of movement, specifically external rotation. In both forms of shoulder replacement, most improvement occurred by 6 months, with some additional improvement up to 2 years. Although the indications for TSR and RTSR are substantially different, the improvement in outcome measures over time can be expected to be very similar.
Another study performed a mid to long term follow up in patients with either a TSR or a RTSR. The purpose of the study was to evaluate functional outcomes, complications, and reoperations of TSR versus RTSR at a minimum eight-year follow-up. Similar to the first study, they found greater postoperative shoulder range of movement in the TSR compared to the RTSR. The traditional group demonstrated significantly greater improvements in external rotation (31° versus 4°) compared to the RTSR group. Gains in forward elevation were similar between TSR and RTSR. The reason as to why RTSR group had reduced external rotation was most likely related to prior rotator cuff issues.
A similar study evaluated a cohort of 19 patients who underwent TSR on one side and RTSR on the other. When asked which shoulder they preferred, 68% preferred the RTSR side, suggesting that the shoulder range of movement limitations may not have a significant functional impact with activities of daily living. Furthermore, this study found subjective satisfaction was greater in shoulders treated with RTSR. Ninety percent of RTSR patients rated their shoulder as much better or better than before surgery, compared to 67% of TSR patients. Additionally, 19% of TSR patients rated their shoulder as worse, compared to 2% of RTSR patients.
Therefore, from these two studies we can expect both shoulder groups to perform similarly in the long term. However, RTSR is more likely to result in patient satisfaction with fewer complications and lower rates of reoperation. Surgeons and patients should consider these differences when considering which procedure to do.
References
- Simovitch, R. W (2017). Rate of Improvement in Clinical Outcomes with Anatomic and Reverse Total Shoulder Arthroplasty. The Journal of Bone and Joint Surgery, 99 (21), 1801-1811. https://journals.lww.com/jbjsjournal/abstract/2017/11010/rate_of_improvement_in_clinical_outcomes_with.3.aspx
- Schoch BS, King JJ, Zuckerman J, Wright TW, Roche C, Flurin PH. (2021). Anatomic versus reverse shoulder arthroplasty: a mid-term follow-up comparison. Shoulder and Elbow, 13 (5), 518-526. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8512971/
