Clinical and radiographic outcomes at 5-8 years of the Catalyst CSR stem-free ellipsoid anatomic total shoulder arthroplasty in a series of 206 shoulders.

Abstract

Anatomic total shoulder arthroplasty (aTSA) using an ellipsoid-shaped stem-free humeral head implant and a multiplanar osteotomy technique has demonstrated advantages in cadaver, biomechanical, radiographic, and short-term clinical studies in reproducing anatomy, reducing outliers, and demonstrating improved early range of motion and good early outcomes. The purpose of this study was to report the outcomes of this implant and method after a minimum 5-year follow-up and compare them with other mid-term reports of implants in the literature. This retrospective study of prospectively collected data included 239 shoulders in 209 patients who underwent aTSA with an ellipsoid stem-free humerus prosthesis and an all-polyethylene glenoid component from the Catalyst CSR Shoulder System between August 2016 and September 2019. Inclusion criteria were patients with advanced glenohumeral joint arthritis with an intact rotator cuff regardless of patient age. Clinical outcomes including range of motion, patient-reported outcome measures, and radiographs were evaluated at multiple time points postoperatively, with a minimum 5-year follow-up. Five-year follow-up or more was achieved in 92% of living patients. There were 206 shoulders in 179 patients that were included in the study with mean follow-up of 71 months (range: 60-100). Mean age at surgery was 72 years (range: 56-90). Forward elevation improved from 113° to 146° (P < .001), external rotation improved from 25° to 49° (P < .001), and internal rotation improved from L5 to L2 (P < .001). There were statistically significant improvements in American Shoulder and Elbow Surgeons score (37 to 94, P < .001), Single Assessment Numeric Evaluation (36 to 95, P < .001), and visual analog scale (6.7 to 0.4, P < .001), all exceeding thresholds of minimal clinically important difference and substantial clinical benefit. Seventy seven percent of patients reported a Single Assessment Numeric Evaluation score ≥ 95 at final follow-up. Preoperative glenoid morphology did not appear to have an effect on clinical or functional outcome scores. There were no implant failures of the humerus component in any patients and no radiographic signs of humerus loosening in any of the 140 shoulders that had final radiographs. Implant revision rate for any cause was 3% at nearly 6 years. Low-grade medial calcar stress shielding was observed in 1% of patients. At 5-year minimum follow-up, the Catalyst CSR stem-free ellipsoid aTSA reliably restores anatomy, provides excellent patient satisfaction, clinical improvement in all outcome measures studied, low rates of revision, and no radiographic signs of humerus loosening.