Comparison of humeral head resurfacing versus stemless humeral components in anatomic total shoulder arthroplasty: a multicenter investigation with minimum 2-year follow-up

Background

The purpose of this investigation was to compare minimum two-year outcomes of anatomic total shoulder arthroplasty (aTSA) performed with humeral head resurfacing (HHR) vs. stemless implants.

Methods

A retrospective review of a large multicenter database was conducted. All patients who underwent aTSA with either HHR or stemless implants with minimum two-year follow-up were evaluated. Range of motion (ROM) and patient-reported outcomes (PROs) including Constant Score, Simple Shoulder Test (SST), American Shoulder and Elbow Surgeons score, University of California Los Angeles Shoulder Score, Shoulder Pain and Disability Index, and Shoulder Arthroplasty Smart score were collected for all patients presurgery and postsurgery. Radiographic data was collected to determine the presence of radiolucent lines as well as evaluate implant sizing and anatomic shoulder restoration.

Results

Overall, 127 patients were included with 49 patients receiving HHR and 78 stemless aTSA. Preoperatively, patients in the HHR group had worse ROM and PRO scores (P < .05). Although the stemless group had significantly greater active abduction (148 ± 28 vs. 116 ± 22, P < .001), forward flexion (154 ± 21 vs. 141 ± 15, P < .001) and external rotation (50 ± 16 vs. 34 ± 17, P < .001) and exhibited better scores on the SST (10.4 ± 2.0 vs. 9.5 ± 1.9, P = .014) at final postoperative evaluation, the HHR group had a greater improvement from preoperative to final postoperative evaluation in active forward flexion (50 ± 22 vs. 32 ± 20, P < .001) and internal rotation (3 ± 2 vs. 1 ± 2, P = .004) as well as all PROs measured (P < .01). Both groups demonstrated significant improvements in all PROs and ROM from presurgery to postsurgery (P < .05). Rates of overstuffing (8.7% in HHR vs. 20.8% stemless, P = .098), oversizing (39.1% in HHR vs. 31.3% in stemless, P = .436), and radiolucent lines around the glenoid components (13.0% in HHR vs. 18.8% in stemless, P = .450) were not significantly different between the groups. One patient in the stemless group required a revision surgery for aseptic glenoid loosening, otherwise no other major complications were reported.

Conclusion

aTSA performed both with stemless implants and HHR resulted in significant improvements in ROM and multiple PROs at minimum two-year follow-up with a low complication rate. The HHR group had worse preoperative shoulder function, which contributed to a greater magnitude of improvement in ROM and across all PROs from presurgery to postsurgery, despite the stemless group having better ROM and SST scores at final follow-up.