Side-to-side differences of three-dimensional knee kinematics during walking by normal subjects

[Purpose] The purpose of this study was to determine the normal range of the side-to-side difference in three dimensional knee kinematics measured by the point cluster technique (PCT). [Subjects] The subjects were twenty-one healthy normal volunteers without knee pain or an episode of injury to the legs. [Methods] The subjects were tested bilaterally at a self-selected normal walking speed and six degrees of freedom knee kinematics were measured using the PCT, and the 95% confidence intervals of the average side-to-side differences in flexion-extension (FE), adduction-abduction (AA), internal-external (IE) rotation, and anterior-posterior (AP), medial-lateral (ML), superior-inferior (SI) translation in each stage of the gait cycle were determined. [Results] The average side-to-side differences and their 95% confidence intervals in rotation/translation in each stage of the gait cycle were determined. The side-to-side differences in AA rotation and AP translation of the tibia were significantly larger in the swing phase than in the stance phase. [Conclusion] The side-to-side differences in AA rotation and AP translation were highly dependent on the stage of the gait cycle. Therefore, the normal ranges of the side-to-side differences in knee kinematics in each stage of the gait cycle, in particular AA rotation and AP translation of the tibia, is useful information for evaluating knee kinematics during walking.