Midterm results of stemless impaction shoulder arthroplasty for primary osteoarthritis: a prospective, multicenter study

Background Stemless shoulder arthroplasty using four open-fin press-fit anchors has been showing promising short-term clinical and radiographic results for patients primary osteoarthritis. This prospective, multicenter study presents 5-year postoperative clinical and radiological outcomes of a stemless shoulder arthroplasty for primary osteoarthritis. Methods Between November 2012 and December 2015, 100 patients were treated for primary osteoarthritis with the Sidus® stem-free shoulder system at 7 European centers. Clinical assessment included the Constant-Murley score (CS), American Shoulder and Elbow Standardized Shoulder Assessment Form score (ASES), Subjective Shoulder Value (SSV) and range of motion (ROM). True anteroposterior, axial and lateral radiographs were reviewed for osteolysis, glenoid and humerus loosening, heterotopic ossification, radiolucent lines, component migration and humeral bone resorption. In addition to a Kaplan-Meier survival analysis, a comparative analysis between total shoulder and hemiarthroplasty was performed. Results Seventy-one patients (36 females) with a mean age of 63.8 years (range: 47-79 years) were available for the 5-year clinical and radiographic follow-up (range: 52-79 months). There was a significant increase (p < .0001) in all outcome scores compared to baseline values. Patients with total shoulder arthroplasty (n=48) achieved significantly better functional outcome than patients with shoulder hemiarthroplasty (n=23) with regard to the absolute and relative CS, ASES and SSV as well as greater abduction strength and ROM in forward elevation and external rotation (p ≤ .004). There were no cases of osteolysis or humeral loosening. There were some cases of heterotopic ossification (1.4%), radiolucency around the humerus (1.4%) or glenoid (25%), glenoid migration (2.1%), inferior osteophytes (1.4%) or humerus bone resorption (9.9%). The 5-year survival was 94%. Conclusion Patients treated with the Sidus® stem-free shoulder system for primary osteoarthritis continue to achieve good clinical and radiographic results without any signs of aseptic humeral implant loosening at 5 years postsurgery.