Risk of insufficient internal rotation after bilateral reverse shoulder arthroplasty: clinical and patient-reported outcome in 57 patients.

BACKGROUND

Bilateral reverse shoulder arthroplasty (RSA) is controversial because of potential rotational deficits impairing daily living activities. We assessed achievement of insufficient internal rotation (IR) and associated factors in bilateral RSA patients.

METHODS

Fifty-seven staged bilateral RSA patients with a minimum of 1 year of follow-up after the second intervention were identified from our local monocentric register. Shoulder range of motion (including IR using the Apley scratch test), strength, and Constant and Shoulder Pain and Disability Index scores were assessed preoperatively and 6, 12, and 24 months postoperatively.

RESULTS

Before surgery, both shoulders were similar regarding imaging parameters, but first operated shoulders tended to have poorer function. One year after the first RSA, 21% of patients had insufficient IR (not reaching the lumbosacral junction) compared with 33% after the second intervention (P = .180). At 2 years, 5% of patients had insufficient IR on both sides. Patients with insufficient IR on the second side at baseline (relative risk [RR], 1.8 [1.0-3.2]) and patients with insufficient IR 1 year after the first RSA (RR, 3.0 [1.6-5.6]) were more likely to have insufficient IR 1 year after the second RSA. Constant and Shoulder Pain and Disability Index scores and abduction of the second side were significantly worse 1 year after the second RSA (P ≤ .047); at 2 years, there were no differences in functional outcome between shoulders.

CONCLUSION

A minority of bilateral RSA patients did not achieve sufficient IR on at least 1 side. Staged surgery is justified, particularly when the outcome of the initial operation is satisfactory.