Are There Biomechanical Differences in Repair Technique for Lesser Tuberosity Osteotomy with Stemless Total Shoulder Arthroplasty?

Background Total shoulder arthroplasty (TSA) has evolved as a treatment for advanced shoulder osteoarthrosis, with stemless implants gaining popularity due to reduced risks of stress shielding and complications associated with stemmed designs. However, the optimal technique for repairing the subscapularis with lesser tuberosity osteotomy (LTO) during TSA remains under investigation. This study evaluates the biomechanical performance of two repair techniques—bone tunneling and suture anchors—used for LTO in the context of stemless TSA. Methods Ten shoulders from 6 cadaveric specimens (3 male and 3 female; aged 58–93 years old) were prepared and allocated to bone tunneling or suture anchor repair groups. Cyclic loading tests were performed, followed by incremental load-to-failure protocols. Outcomes included repair gapping during cyclic loading, initial repair stiffness (derived as the average secant stiffness for 10 of the initial 3000 cycles prior to fatigue), cycles to failure, displacement of repair and load to failure. Results The mean age of the cadavers used in this study was 90.2 ± 14.7 years. Mean failure load were alike, and cycles to failure nearly identical, between groups (p = 0.86-1.00). No significant differences were observed between the two groups in repair gapping during cyclic loading (p = 0.42). However, a nonsignificant trend was observed for initial repair stiffness (p = 0.07), with the tunnel group showing greater stiffness (62.5 ± 13.9 N/mm) compared to the anchor group (46.0 ± 10.6 N/mm). A trend was also noted in displacement of repair (p = 0.099), with the tunnel group exhibiting greater displacement (41.4 ± 17.3 mm) than the anchor group (23.0 ± 13.1 mm). Conclusion This study suggests that both techniques may yield comparable biomechanical outcomes in cadaveric models of LTO repair, which warrants further exploration. As a pilot project, this study lays the groundwork for future research that could expand upon these preliminary results and contribute to a deeper understanding of LTO repair techniques.