Proprioceptive Acuity in Active Rotation Movements in Healthy Knees

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Muaidi QI, Nicholson LL, Refshauge KM. Proprioceptive acuity in active rotation movements in healthy knees. Objectives To investigate the ability of asymptomatic participants to discriminate between active knee rotation movements of different magnitude and to determine whether proprioceptive acuity of active knee rotation differs between limbs (dominant and nondominant and right and left). Design Cross-sectional study. Setting Laboratory in an Australian university. Participants Healthy volunteers (N=30) without previous cruciate ligament injury or surgery, previous fracture of the lower limbs, or other lower-limb disorders in the last 3 months. Interventions Not applicable. Main Outcome Measures Knee rotation proprioceptive acuity was determined by using our custom-designed device. The measure of proprioceptive acuity used in this study was the just-noticeable difference (JND). Participants actively rotated the knee (internal or external rotation) to 1 of 4 movement blocks and judged the magnitude of the permitted motion. Proprioceptive acuity scores, representing a participant’s ability to detect small differences in magnitude of active knee rotation movements, were then calculated. Results The means of the JND for proprioceptive acuity of internal rotation (1.37°±.11°) were significantly ( P=.04) lower than for external rotation (1.6°±.14°) regardless of side (right, left) or dominance. No significant difference was found between the mean JND for left and right knee rotations ( P=.84) or between the mean JND for dominant and nondominant knee rotation ( P=.69). Conclusions Participants perceived smaller differences between active internal rotation movements than external rotation. No significant difference was found between the dominant and nondominant leg or between the left and right leg; therefore, clinicians can establish whether a proprioceptive deficit exists after unilateral injury and can use acuity of the uninjured knee as a normal status for rehabilitation.