BIOMECHANICS OF NORMAL AND ANTERIOR CRUCIATE LIGAMENT DEFICIENT GAIT UNDER BRACED AND UNBRACED CONDITIONS

Abstract

The anterior cruciate ligament (ACL) performs an important role in stabilizing the knee joint during gait. However, little research has examined the effect of ACLdeficiency on gait mechanics. Furthermore, the mechanics of braced ACL-deficient gait remain unclear. The purposes of this study were to evaluate the running mechanics of normal and ACL-deficient individuals, and secondly, to investigate the running mechanics of normal and ACL-deficient Individuals while wearing a derotation knee brace. Seven ACL-deficient individuals (X age = 25 +I- 5 yrs, X height = 1.80 +I- .07 m, X mass = 85.0 +/ 16 kg) and seven uninjured males (X age = 24 +I- 2 yrs, X height = 1.80 +/- .05 m, X mass = 86.0 +I- 5 kg) participated. Subjects were filmed during braced and unbraced straight-lie running across a force platform (cadence = 77 cycles-perminute). One acceptable trial was recorded for each subject under braced and unbraced conditions. Running velocities were 3.24 m/s and 3.50 m/s for normal and ACL-deficient subjects, respectively. Selected kinematic and kinetic parameters were calculated to quantify the differences between normal and ACL-deficient individuals, and the effect of bracing the knee. A 2 X 2 repeated measures analysis of variance revealed no statistically significant difference on any dependent variable (a = .05). It appears that ACL-deficiency may not alter the running mechanics of wellrehabilitated individuals during a low-risk, non-fatigued running task. Bracing the knee seemed to have no effect on the gait mechanics of normal or ACL-deficient individuals. The assessment of ACL-deficiency and bracing may require more demanding experimental protocol and/or newlyinjured/less-rehabilitated subjects. Future studies may benefit from an examination of the muscle moments at the occurrence of specific events during the support period.