Biomechanics of the knee with isolated one-bundle tear of the anterior cruciate ligament

Abstract

This history of previous studies has resulted in the current confusion concerning the definition of the partial ACL tear in the clinical field. The purpose of this chapter was to introduce the changes in the kinematics of the knee that result from isolated deficiency of the anteromedial (AM) or posterolateral (PL) bundle of the anterior cruciate ligament. Anterior translation laxity under an anterior tibial load, rotational laxity under an internal tibial torque, and anterior translation laxity under pivot shift loading were significantly different between the knees with AM and PL bundle deficiencies, but the changes were small: less than 3 mm or 1.5°. An isolated AM or PL bundle tear caused a small increase in laxity. If there is a clinically identifiable increase in laxity - in addition to the isolated tear of the AM or PL bundle - there must also be a tear of the other bundle of the ACL or at least a partial tear.