Native Anterior Cruciate Ligament Obliquity versus Anterior Cruciate Ligament Graft Obliquity

Abstract

Background The goal of anterior cruciate ligament reconstruction is to attain a graft that closely resembles the native anterior cruciate ligament anatomy. By reconstructing the original anatomy, one hopes to eliminate issues related to graft elongation, impingement, and excessive tension while achieving ideal knee kinematics. Hypothesis Clinical grafts placed using the transtibial technique will differ in the sagittal and coronal planes when compared with obliquity of the anatomic anterior cruciate ligament. Study Design Controlled laboratory study/case series; Level of evidence, 4. Methods With the assistance of computer navigation, our study compared the anterior cruciate ligament orientation of 5 cadaver knees with 12 clinical anterior cruciate ligament—reconstructed knees using the transtibial technique. Results Clinical graft obliquity differed from the anatomic anterior cruciate ligament in all flexion angles 0°, 30°, 60°, and 90°. In the sagittal plane, the clinical graft obliquity differed from the anatomic anterior cruciate ligament by 13.6°, 12.7°, 16.7°, and 17°, respectively. In the coronal plane, the clinical graft obliquity differed from the anatomic anterior cruciate ligament by 4.9°, 7.6°, 8.9°, and 12.7°, respectively. Paired t tests demonstrated that the difference between the clinical and anatomic anterior cruciate ligament was significant (P < .05), except in the coronal plane at 0° of flexion. In spite of this, all patients demonstrated a negative pivot shift and Lachman at the conclusion of their reconstructions and at 6-month follow-up. Conclusion The sagittal and coronal plane obliquity of well-functioning grafts placed using the transtibial technique were more vertical than anatomic fibers. Clinical Relevance Graft obliquity, in both the coronal and sagittal plane, may be an important means to target appropriate anterior cruciate ligament graft position and can be monitored using surgical navigation systems.