NOVEL TECHNIQUE FOR REPAIRING PARTIAL ACL TEARS: BIOMECHANICAL ANALYSIS OF AN OSTEOTOMY USING A CADAVERIC MODEL

Abstract

Introduction: Partial ACL tears can result in knee instability despite continuity of native ACL tissue with its femoral and tibial attachments. Though current treatment consists of replacement of the residual ACL, we propose that retensioning the residual ACL can restore knee stability. Thus, our aim was to assess if a coring osteotomy restores joint stability after a partial ACL tear in a cadaveric model. Methods: Adult cadaveric knees were used. Baseline translational and rotational measurements were obtained for each knee at 30° and 90° of knee flexion with a MTS Bionix 858 machine with the ACL intact, as well as after each subsequent intervention. First, we sectioned the anteromedial ACL bundle to replicate a partial ACL injury. Subsequently, an oblique coring osteotomy was performed. The osteotomy was both rotated to centralize and then distalized to retension the posterolateral ACL bundle. Finally, an ACL deficient knee was created as a control, involving complete sectioning of the ACL. Results: Each of the eight knees demonstrated varying degrees of baseline translational (range 3.9-15.8 mm at 90° and 6.2-15.6 mm at 30°) and rotational laxity. Sectioning of the anteromedial ACL bundle resulted in a significantly increased anterior translation in all of the knees at both 90° (p=0.041) and 30° (p=0.0088), without a statistically significant change in rotation (p=0.45). The coring osteotomy improved knee translation compared to the partial ACL injury state in all of the knees at 90° (p=0.0022) and 30° (p<0.001), again without a change in rotation (p=0.053). Five of the 8 osteotomized knees had less translation than the intact state, and the other 3, the values neared the intact state, had greater anterior translation than the intact state. Finally the ACL deficient knees demonstrated both increased translation compared to both the intact (p=0.0015 at 90° and p<0.001 at 30°) and partially sectioned states (p=0.036 at 90° and p=0.0094 at 30°). Conclusions: In our cadaveric model, we demonstrate that a coring osteotomy of the residual ACL fibers can be used to restore knee stability after a partial ACL tear, while preserving the native ACL. Further studies are needed to validate this procedure. Fig. 1: Displacements Across Each State at 90 Degrees Knee Flexion Fig. 2: Displacements Across Each State at 30 Degrees Knee Flexion