The impact of glenoid parameters and implant overstuffing on functional outcomes of shoulder hemiarthroplasty in patients with glenohumeral joint arthritis.

PURPOSE: The outcomes of shoulder hemiarthroplasty are highly dependent on the baseline glenoid morphology and the rotator cuff integrity. The objective of this study was to assess whether certain glenoid parameters and implant overstuffing are associated with worse clinical outcomes following shoulder hemiarthroplasty.

METHODS: We retrospectively reviewed 25 patients who underwent shoulder hemiarthroplasty for shoulder arthritis, with a mean follow-up of 5.3 years. The baseline glenoid morphology, the glenoid wear rate, the proximal humeral head migration and implant overstuffing were evaluated radiologically in all patients. The radiological parameters were correlated with the functional outcomes.

RESULTS: The Constant-Murley score, the ASES score, and the OSS score were significantly better for patients with a concentric baseline glenoid compared to those with an eccentric glenoid. The Constant-Murley score and the ASES score were also improved in patients without implant overstuffing compared to patients with implant overstuffing (p < 0.05). However, glenoid wear was not associated with worse functional outcomes (p = 0.23 for Constant-Murley score, p = 0.15 for ASES score and p = 0.27 for OSS score). Last, a worse Constant-Murley score was strongly correlated with proximal humeral head migration (p < 0.001), while worse ASES and OSS scores were moderately correlated with proximal humeral head migration (p < 0.001).

CONCLUSION: Our findings indicate that the results of hemiarthroplasty can be improved through careful selection of patients upon the baseline glenoid type morphology and proper implant sizing to avoid implant overstuffing. Moreover, glenoid wear is not associated with worse clinical outcomes, therefore shoulder hemiarthroplasty should be reconsidered as an alternative in younger patients with shoulder arthritis.