Abstract
INTRODUCTION: The study aimed to compare the biomechanical impact and reaming performance of two intramedullary bone graft harvesting techniques: the established Reamer-Irrigator-Aspirator 2 (RIA 2) system and a novel aspirator+reaming-aspiration (ARA) concept. MATERIALS AND METHODS: In a preclinical in vivo sheep model, sixteen femora were assigned to either the RIA 2 or ARA group (n = 8 each). Biomechanical testing, computed tomography (CT)-based 3D bone geometry analysis, and fracture line assessment were performed postoperatively. Bending stiffness of the reamer shafts, cortical wall thickness pre- and post-reaming, and torsional stability of reamed femora were evaluated. Statistical analysis included TOST, Mann-Whitney U, and Shapiro-Wilk tests, considering values of p < 0.05 as statistically significant. RESULTS: Both reaming systems produced the greatest cortical thinning medially in the midsections of the analyzed region. No statistically significant differences were observed in postoperative cortical wall thickness, bone removal rates, or torsional stability between groups (all p > 0.05). Bending stiffness was significantly higher for the RIA 2 system (p = 0.004). In both groups, fractures predominantly initiated medially or at sites of previous drill holes. The ARA concept demonstrated equivalent biomechanical and reaming performance compared to the RIA 2 system, with a comparable safety profile. CONCLUSIONS: In this preclinical in vivo comparison, the RIA 2 system and the ARA concept with BixCut reamers demonstrated equivalent reaming performance regarding cortical bone removal and femoral shaft geometry. Although the RIA 2 drive shaft exhibited greater bending stiffness, both systems induced comparable medial cortical thinning in the mid-diaphyseal region. Three-dimensional geometric analysis and ex vivo biomechanical testing showed no significant differences in residual cortical thickness or torsional stability. Fracture patterns were similar and correlated with areas of maximal medial thinning. Overall, both systems provided comparable reaming functionality and biomechanical outcomes. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00402-026-06270-y.