Anatomic total shoulder arthroplasty using a stem-free ellipsoid humeral implant in patients of all ages.

ABSTRACT

BACKGROUND: Stem-free shoulder arthroplasty has recently been shown to have comparable results to stemmed arthroplasty, though stemless designs are typically used in a younger patient population. Additionally, although the native humeral head is elliptical in shape, clinical results with ellipsoid implants in shoulder arthroplasty have not been reported on previously. This case series reports on the outcomes of a recently introduced anatomic total shoulder arthroplasty with an ellipsoid-shaped articular surface and unique multiplanar platform type of stemless fixation. METHODS: This retrospective case series examines the initial cohort of patients who received an anatomic total shoulder arthroplasty using an ellipsoid stem-free humeral prosthesis and an all-polyethylene glenoid component from the Catalyst CSR Total Shoulder System (Catalyst OrthoScience) over a 1-year period. Inclusion criteria were patients with a diagnosis of advanced glenohumeral joint arthritis with an intact rotator cuff, regardless of patient age. Clinical outcomes including shoulder range of motion and patient-reported outcome measures, as well as radiographs, were evaluated at multiple time points postoperatively, with minimum 2-year follow-up. RESULTS: Sixty-three shoulders in 57 patients with a mean age of 73.0 years (range 60-85 years) were included in the study with a mean follow-up period of 30.5 months (range 24-41 months). Forward elevation improved from 121° to 150° (P < .0001), external rotation improved from 28° to 48° (P < .0001), and internal rotation improved from L3 to L1 (P < .001). There were statistically significant improvements exceeding the minimal clinically important difference (MCID) in the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) score (37 to 94, P < .001), Single Assessment Numeric Evaluation (SANE) (40 to 93, P < .001), visual analog scale (6.3 to 0.4, P < .001), and Patient-Reported Outcomes Measurement Information System physical domain T score (44 to 57, P < .001). The improvement in the ASES score also exceeded the threshold for the substantial clinical benefit. Age, sex, and preoperative glenoid morphology did not appear to have an effect on the clinical outcome scores. There were no implant failures or evidence of radiographic loosening of the humerus component in any patients. CONCLUSION: At 2-year minimum follow-up, this stem-free ellipsoid humerus total shoulder arthroplasty provides very good results with high patient satisfaction, clinical improvement in all outcome measures studied, and no signs of loosening.