Short term results of anatomic stemless shoulder replacement with peripheral neck fixation

Abstract

Most of the current stemless implants are using a central neck fixation design. Easytech Stemless replacements (FX Solutions®, Viriat, France) were developed promoting the idea of peripheral fixation of the stemless implant. The aim of this study was to analyze clinical and radiological results of this stemless TSA implanted for osteoarthritis (OA). A retrospective study of patients who received TSA with the Easytech® Anatomical Shoulder System (FX Solutions®, Viriat, France) for OA was completed at five clinical sites. Preoperative and minimum 2 year follow-up Constant Scores and X-rays were evaluated. Two independent orthopedic surgeons analyzed X-rays to assess anatomy reconstruction and component migration. Revisions and serious adverse effects were reviewed. 129 patients were analyzed with an average follow-up of 37.47 months (24-54). Seven patients had a revision surgery and one of these resulted in the removal of the Anchor Base. The postoperative Constant Scores showed significant improvement with a mean raw Constant Score of 73.78 (38.0-100.0, mean increase 40.96, P<.0001) and mean adjusted Constant Score of 99.14 (42.20-133.30, mean increase 55.68, P<.0001). Radiographic review demonstrated that no modification of the center of rotation (COR) at minimum 24 months was greater than 3 mm and in comparison to preoperative radiographs, restoration of COR was lateralized in 25% of the cases, medialized in 61.5% and 13.5% had no change in COR. The mean value of the cervico-diaphyseal angle was 130.2° (114; 149) at 3 weeks and 129.9° (113.5; 144.0) at 2 years, demonstrating no significant difference (P=.16). 36 patients (35%) had calcar remodeling. Univariate and multivariate logistic regression found no significant factor, which was associated with the variation of the cervico-diaphyseal angle over time, center of rotation, calcar remodeling, or final Constant Score. The Walch B2 and C glenoid subset of patients (n=13) had overall survival rate of 90.9% [95% CI 75.4-100.0] vs. 98.0% [95% CI 95.3-100.0] in other glenoid types (P<.01). Walch B2/C patients were 4.44 [95% CI 1.13, 17.6] times more likely to have a Constant Score <85 (P=.03). The peripheral fixation of the Easytech® Anatomical Shoulder System for OA provides excellent clinical results and imaging stability at minimum two year follow-up. Elderly age, gender and BMI do not affect the stability.