Biomechanical study of optimum anchorage in dome-shaped high tibial osteotomy

Abstract

Purpose: There has been no report to date on any biomechanical study regarding the strength of fixation at the osteotomy site in dome-shaped high tibial osteotomy (HTO). In this study, we evaluated the biomechanical strength of a spacer that we improved and determined the medial site of HTO. Methods: HTO correction angles of 15° and 20° were used in all experiments, which were performed on lower leg specimens from pigs (n = 12). The osteotomy site was fixed by a locking plate and screws with a spacer. Compression (600 N/min until 1100 N) and extended cyclic loading (200 cycles at 1000–2000 N) were performed to compare initial displacements in HTO specimens with and without spacers. Results: The reduction ratios of displacement with and without spacers at HTO correction angles of 15° and 20° were 37% and 27%, respectively. No effect of the spacer at the correction angle of 15° was observed in the cyclic loading; however, the maximum displacement and amplitude were reduced with the spacer at the correction angle of 20°. Conclusions and clinical relevance: When the HTO correction angle is small, the effect of the spacer is uncertain. However, the spacer is effective at an HTO correction angle of 20°.