Early dislocation after reverse total shoulder arthroplasty

Abstract

Background: Although instability can occur after reverse total shoulder arthroplasty (RTSA), the risk factors, the treatment, and ultimate fate of the implant in these patients remains poorly understood.

Methods: Demographics, acute treatment, and the need for revision were evaluated in all patients with RTSAs who sustained a subsequent dislocation within the first 3 months. Standardized outcome scores were collected preoperatively and at the final follow-up.

Results: Atraumatic instability occurred in 11 patients (incidence, 2.9%) treated with RTSA early (before 3 months postsurgery). The mean time to dislocation was 3.4 weeks. These patients tended to be previously operated-on (64%), male (82%), overweight (mean body mass index (BMI) of 32.2 kg/m(2), with 82% having a BMI ≥30 kg/m(2)), and without a satisfactory subscapularis repair at initial RTSA (64%). Initial treatment included closed reduction in 9 patients, open reduction in 1, and open reduction with a thicker polyethylene insert in 1. Four experienced recurrent instability requiring a thicker polyethylene insert. Two additional patients were converted to hemiarthroplasty due to persistent instability. Visual analog pain scores (P = .014) and American Shoulder and Elbow Surgeons scores (P = .018) were significantly improved. Simple Shoulder Test scores trended towards improvement (P = .073).

Conclusions: Early dislocations of the RTSA prosthesis were uncommon. The most common associated factors were a BMI >30 kg/m(2), male gender, subscapularis deficiency, and previous surgery; in these patients, we now use an abduction orthosis. Closed reduction alone was successful in 4 of the 9 closed reductions (44%). Five of 11 RTSAs (45%) required polyethylene exchange. The RTSA was retained in 82%, 36% with the original implant.

Keywords: Reverse total shoulder arthroplasty; complication; dislocation; revision; shoulder instability.