Anatomic total shoulder arthroplasty using hybrid glenoid fixation with a porous-coated titanium post. Two- to ten-year follow-up of 256 cases with primary glenohumeral osteoarthritis

Background

Anatomic total shoulder arthroplasty is one of the recommended surgical treatments for severe glenohumeral osteoarthritis, providing good pain relief and function. Aseptic loosening of the glenoid component, however, is a major cause for revision. Hybrid components have been introduced, combining traditional cemented fixation with porous titanium bone ingrowth to improve fixation. The purpose of this study was to report our midterm to longterm experience using such a component, including clinical outcomes and implant survival.

Methods

We reviewed all patients who were operated for primary osteoarthritis during the period 2011-19, leaving a minimum of 2-year follow-up. The severity of the osteoarthritis was graded using Samilson-Prieto score, while glenoid morphology was graded using the modified Walch classification. Clinical outcomes included Western Ontario Osteoarthritis of the Shoulder (WOOS) index, EQ-5D-5L, and Constant-Murley score. Postoperative radiographs were analyzed for radiolucent lines. Patient records were studied for complications including revisions. Supplementary data for revision and outcome were obtained from the Danish Shoulder Arthroplasty Registry. Kaplan-Meier estimates for implant survival were calculated.

Results

A total of 256 arthroplasties in 224 patients were included (mean age: 69 years ± 9 years, 149 females). 81% of cases were graded radiographically as severe osteoarthritis, according to Samilson-Prieto. Walch type B1 was most commonly followed by B2 (29% and 28% respectively). The mean follow-up time was 49 months (range 24-127). The response rate for patient reported outcomes was 91%. The median WOOS index was 94% (81%-99%), the median EQ-5D-5L was 0.87 (0.69-0.95), and the mean Constant-Murley score was 75 (SD 17.7). 13 cases (6%) had a WOOS index below 50%. 8.2% had complications related to surgery. A radiolucent line had developed around the central post in six cases and at the bone-cement interface in three cases at follow-up. Six cases had been revised (2.3%); three due to aseptic loosening of the glenoid. The 10-year survival estimate was 95.6 % (95% CI: 87.9%-98.5%).

Conclusion

Anatomic total shoulder arthroplasty with hybrid glenoid fixation provides excellent clinical outcome with a low complication rate in patients, with primary glenohumeral osteoarthritis. The 10-year survival rate is high and comparable to that reported for the best- performing all-polyethylene components. Longer observation is needed to see if hybrid fixation will outperform standard all-cemented components.