Postural control - a comparison between patients with chronic anterior cruciate ligament insufficiency and healthy individuals

Postural control in the sagittal plane was evaluated in 22 patients with ch ronic anterior cruciate ligament (ACL) deficiency and the result was compar ed to that of a control group of 20 uninjured subjects. Measurement of the body sway was done on a fixed and sway-referenced force plate in both singl e-limb and two-limb stance, with the eyes open and closed, respectively. Fu rther, an analysis of the postural reactions to perturbations backwards and forwards, respectively, was made in single-limb stance. The results demonstrated statistically significant deficits of the postural control in the patient group compared to the control group, but also withi n the patient group. There was a significantly higher body sway within the patient group when standing on a stable support surface on the injured limb than standing on the uninjured limb with the eyes open, but no difference with the eyes closed. When standing on a stable support surface, there was a significantly higher body sway in the patient group standing on the injur ed leg than in the control group, both with eyes open and closed. The patie nt group also showed a significantly impaired postural control compared to the control group when standing on the uninjured leg with the eyes closed. There was no difference between the groups in the two-limb stance. When sta nding on the sway-referenced support surface, the patient group had a signi ficantly larger body sway than the control group when the eyes were open, b ut there was no significant difference between the groups with the eyes clo sed. The measurement of the postural corrective responses to perturbations backwards and forwards showed that the reaction time measured from the init iation of the force plate translation, and the amplitude of the body sway w as significantly greater in the patient group than in the control group. We conclude that patients with a continuing chronic ACL insufficiency sever al years after injury have an impaired postural control in the anteroposter ior direction in single-limb stance on their injured leg. They also show a greater body sway and a prolonged reaction time when subjected to antero-po sterior perturbations when standing on their injured leg.