Association of lateral humeral offset with functional outcome and geometric restoration in stemless total shoulder arthroplasty

Background Restoration of shoulder geometry is desirable in total shoulder arthroplasty (TSA) and thought to influence the postoperative clinical outcome. We aimed to study the association of postoperative lateral humeral offset (LHO) changes and clinical outcome, as well as to investigate the ability of stemless anatomic TSA to restore shoulder geometry. Methods In patients with primary shoulder osteoarthritis who underwent stemless anatomic TSA, the preoperative and postoperative clinical outcome was measured. Shoulder geometry was measured on preoperative computed tomography for the osteoarthritic shoulder and contralateral healthy shoulder and on postoperative computed tomography for the operated shoulder. Results Forty-four patients with a minimum follow-up of 12 months (range, 12-50 months) were available for the study. Postoperatively, the clinical outcome measures improved. The postoperative difference in LHO between the operated shoulder and contralateral healthy shoulder was 1.3 ± 4.6 mm and was correlated with scores on the short version of the Disabilities of the Arm, Shoulder and Hand questionnaire at 3 months (Pearson correlation = 0.36, P = .01) and visual analog scale for pain at rest (Pearson correlation = 0.30, P = .03) and with exertion (Pearson correlation = 0.34, P = .01) at 3 months. Lengthening of LHO was associated with worsening shoulder function at 3 months but not at 12 months. The postoperative shoulder geometric parameters were restored postoperatively to acceptable ranges. Conclusion The stemless anatomic TSA could restore shoulder geometry in an acceptable manner. At 3 months but not at 12 months, increased LHO had a negative effect on shoulder function and resulted in more shoulder pain at rest and with exertion but did not affect quality of life, health status, or range of motion.