Partial Tear of the Anterior Cruciate Ligament: Management with One-Bundle Augmentation Technique

Introduction

The anterior cruciate ligament (ACL) consists of two distinct bundles, termed anteromedial (AM) and posterolateral (PL), based on their tibial insertions. Biomechanical studies have shown that both bundles contribute synergistically to knee stability throughout the joint’s range of motion. However, their function is distinctively diverse because the AM fibers are primarily tense in flexion, whereas the PL fibers are more tense in extension.

Injuries of the ACL are very common, and in the United States approximately 100,000 ACL reconstructions are performed annually. Although the majority of these injuries are complete tears of the ACL, the rate of partial tears has been reported to range between 5% and 28% ; however, the criteria of a partial ACL tear in most of these studies were not anatomical because they do not report specifically if the rupture involved the AM or the PL bundle of the ACL. According to these studies, an ACL injury was classified as partial when a minimum of one-third of the remaining intact fibers sustained tension on probe testing during arthroscopy, and when the ACL remnant was bridging the femur and tibia. Studies have suggested defining partial ACL tears as those involving rupture of one bundle (the AM or PL) while the healthy bundle is potentially functional as judged by palpation with a probe.