Evaluation of clinical and radiographic outcomes after total shoulder arthroplasty with inset Trabecular Metal-backed glenoid.

Abstract

Trabecular Metal (TM)-backed glenoid implants were introduced for their theoretical ability to increase osseointegration while minimizing wear and the risk of loosening in total shoulder arthroplasty (TSA). Initial follow-up studies of TM-backed glenoids demonstrated high rates of metallic debris formation around the implant site, raising concerns about longevity. More recent data suggest that metallic debris formation may be less prevalent than previously reported and that the implants may have positive long-term outcomes regardless of debris. The goal of our study was to assess the clinical and radiographic outcomes at mid-term follow-up of TSA using a TM-backed glenoid implant placed with full backside support using an inset technique. We hypothesized that our clinical and radiographic outcomes would be good using this technique. We retrospectively reviewed the charts of 39 patients who underwent 41 TSA procedures with a Zimmer Biomet TM-backed glenoid component performed by a single surgeon between January 2010 and March 2016. After exclusions for death unrelated to surgery and loss to follow-up, 35 patients (37 shoulders) with minimum 2-year clinical follow-up were included in the study. The glenoids were all placed in an inset fashion with full backside support. Clinical, patient-reported, and radiographic outcomes were analyzed. The average follow-up period was 7.2 years (range, 2-11 years). At final follow-up, average shoulder elevation was 153° ± 22° and average external rotation was 53° ± 12°. The average American Shoulder and Elbow Surgeons score was 86.8 ± 19.0, and the average visual analog scale score was 1.3 ± 2.4. Metallic debris was found in 9 shoulders (27%), and radiolucency was observed around the glenoid components in 13 shoulders (39%) on the final postoperative radiographs. Metallic debris and radiolucency findings were low in severity, with average grades of 0.32 (standard deviation, 0.54) and 0.39 (standard deviation, 0.50), respectively. There were no reoperations. This study of 37 shoulders undergoing TSA with a TM-backed glenoid demonstrated 100% implant survivorship at an average follow-up of 7 years. Clinical outcomes were excellent despite the occurrence of some metallic debris formation. The findings suggest that a TM-backed glenoid component implanted in an inset fashion to achieve full backside support can provide good clinical and patient-reported outcomes in TSA patients at mid-term follow-up and suggest that continued consideration of the role of TM-backed glenoids and the optimal technique for implantation may be warranted.