Seven-year outcome of a stemless impaction shoulder arthroplasty: a prospective, multicenter study

Background Previously published studies have demonstrated favourable clinical and radiographic outcomes at two and five years postoperatively following stemless shoulder arthroplasty. The objective of this prospective study is to evaluate the clinical and radiological outcomes seven years postoperatively of the Sidus® stem-free shoulder system. Methods 107 patients were eligible for this analysis. Between November 2012 and December 2015, they were treated for primary or secondary osteoarthritis with the Sidus stem-free shoulder system at 7 European centres. Outcome variables included the Constant-Murley Score (CS), the American Shoulder and Elbow Surgeons (ASES) score, the Subjective Shoulder Value (SSV), and shoulder range of motion (ROM). Standardized radiographic evaluations (true AP, axial, and lateral views) were analysed for signs of osteolysis, loosening of the glenoid or humeral components, ectopic bone formation, radiolucent lines, implant movement, and bone loss in the humerus. Pain levels were recorded using the CS pain subscale (0 = severe pain to 15=no pain), along with overall patient satisfaction at each interval. Outcomes of patients treated with a total (TSA) and hemi shoulder arthroplasty (HSA) were compared. A Kaplan-Meier survival analysis was also performed. Results Forty-six patients (23 males, 23 females) with an average age of 60.1 years (ranging from 40 to 79 years) completed the 7-year follow-up examination. Consistent with findings from the 2- and 5-year follow-up, a statistically significant improvement across all clinical outcome measures was observed when compared to baseline values (p<0.05). Constant-Murley Score improved from baseline to 7-years postoperatively from 31.6 to 75.7 points, ASES from 40.7 to 95.5 and SSV from 35.8 to 85.8 % (p < .0001). TSA patients (n=28) achieved significantly better functional outcome in CS (p=0.002), ASES (p=0.002), SSV (p=0.016), pain (p=0.011) and active forward flexion (p=0.012) compared to HSA patients (n=18). Radiographic assessment at the 7-year follow-up demonstrated 4.3% of humerus bone resorption, 39% of radiographic signs of secondary glenoid erosion after HSA and 25% of radiolucent lines (RLL) around the glenoid component for TSA. Kaplan-Meier analysis demonstrated a 7-year implant survival rate of 94%. Conclusion At the 7-year follow-up, the Sidus stem-free shoulder system continues to demonstrate favourable outcomes in the management of primary and secondary glenohumeral osteoarthritis, with consistently good clinical scores and no radiographic evidence of aseptic loosening of the humeral component. Level of Evidence Level IV, Case series, Treatment study