Instability after reverse shoulder arthroplasty with tendon transfer: a case series

Abstract

BackgroundReverse shoulder arthroplasty with tendon transfer (RSA-TT) was introduced by Boileau for patients with rotator cuff arthropathy and combined loss of active elevation and external rotation. TT at the time of RSA has been shown to increase external rotation compared to RSA alone. Postoperative instability following RSA-TT is thought to be an uncommon complication reported in around 5% of cases. We present a novel case series of RSA-TT and postoperative instability. MethodsA multicenter retrospective review was performed identifying patients who underwent RSA-TT between 2008 and 2021. Patients with rotator cuff arthropathy and combined loss of active elevation and external rotation undergoing RSA-TT and aged more than 18 years were included. Revision arthroplasty cases were excluded. Implants and TT technique were selected by the treating surgeon. Patient demographics, surgical data, and postoperative metrics were collected. Continuous variables were calculated as mean and standard deviation and then compared using Student’s t-test. Frequencies and proportions were calculated for categorical variables and compared using Chi-squared test. ResultsThirty-one patients underwent RSA-TT; 21 patients had sufficient follow-up for analysis. Seven patients (25%) had a postoperative dislocation event. Patients with instability were male with average age of 70 ± 6 years and body mass index 29 ± 4 kg/m2. The latissimus dorsi was transferred in all patients with teres major additionally transferred in 2 patients. Subscapularis was repaired in 4 patients, irreparable in 1 patient, and voluntarily not repaired in 2 patients. All dislocation events were anterior and spontaneous without inciting traumatic event. Three patients dislocated within 2 weeks of surgery. Three patients dislocated 1-2 months postoperatively. One patient dislocated nearly 6 months following surgery. At time of revision surgery, TT was intact in all patients. Two patients required multiple revision procedures to attain definitive stability, including one conversion to hemiarthroplasty. The TTs were taken down in 3 patients. At final follow-up, all patients remained stable. There were no documented nerve palsies. Final range of motion for patients with and without instability did not significantly differ. DiscussionThe series suggests that postoperative instability following RSA-TT is more common than previously reported. Despite instability requiring surgical revision, final range of motion did not significantly differ between those with stable and unstable RSA-TT patients. In those who suffered an instability event, dislocation occurred within 2 months of surgery in 86% of cases. It is important to be aware of this elevated risk of instability following this procedure and to tailor rehabilitation protocols accordingly.