Instability arthropathy is a known cause of glenohumeral osteoarthritis (OA) among patients with and without prior shoulder stabilization. This study aims to compare the clinical, radiographic, and patient-reported outcome measure (PROM) scores among total shoulder arthroplasty (TSA) patients with and without a history of shoulder stabilization.
A case-control study was performed comparing 20 patients with a history of anterior shoulder stabilization (11 open, 9 arthroscopic) who underwent TSA to a matched cohort of 20 TSA patients without a history of shoulder surgery (mean follow-up = 2.8 years). Patients were matched by sex, age, and baseline American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) score within 10 points (mean age 59.6 ± 9.6 years). Patient characteristics, operative findings, and preoperative and postoperative radiographic characteristics for both groups were reported. Comparisons were made regarding PROM scores (ASES, 12-Item Short Form Health Survey (SF-12), Shoulder Activity Scale [SAS], numeric rating scale for pain) at baseline, 2 years, and 5 years and patient satisfaction at 2 years.
Intraoperative findings of subscapularis scarring or attenuation was common among patients with prior anterior stabilization. The instability cohort did have a higher percentage of B2/B3 glenoid types than the OA cohort (45% vs. 15%), but this was not significantly different possibly because of the small sample size. At 2 years, both instability and OA groups reported significant improvement in pain, function, and activity level. There was no difference between groups on any PROMs or patient satisfaction level. At 5 years, instability patients had significantly lower scores on the ASES and the SF-12 PCS than the OA group.
There was notable alterations in both soft tissue and bony morphology among patients with prior anterior stabilization. After TSA, both instability and primary OA groups showed significant improvements at 2 years. However, PROMs for instability patients deteriorated at 5 years compared with the control group. Complex bony and soft tissue imbalances may contribute to more unpredictable long-term PROM scores. Thoughtful preoperative consideration of these factors should influence decision making regarding selection of TSA for management of OA in this complex patient cohort.