Description
Objectives: The purpose of this study was to clarify kinematic characteristic of early knee OA based on gait analysis data.
Methods: Seventy patients with knee OA and thirty healthy subjects were included in this study. Six patients who required assistive devices were excluded. Patients with knee OA were classified into non-radiographic OA group (33 knees) and radiographic OA group (31 knees). The maximum knee flexion angle, The maximum angular velocity in the shank, The maximum lateral acceleration of the shank, power spectral density (PSD) of trunk acceleration, gait speed, and stride length were measured by 10m gait analysis with IMUs.
Results: There was a significant difference in the mean maximum knee flexion angle among the three groups, and the maximum knee flexion angle decreased with the progression of OA (56.6°, 46.4°, 35.5°, p <0.05). The mean velocity of each lower leg adduction (9.07deg/s, 15.3deg/s, p < 0.05) and lateral acceleration of the lower leg (2.10m/s2, 3.77m/s2, p < 0.05) were higher in the non-radiographic OA group than in the normal group. The PSD of trunk acceleration was significantly higher in the non-radiographic OA group than in the normal group (0.101, 0.301, p<0.05) for the vertical 2.0 harmonic wave. Walking speed and stride length were also significantly different between the normal group and the non-radiographic OA group. The odds ratios of upper and lower trunk PSD 2.0 times wave were 9.97, lateral acceleration of the lower leg 3.39, and maximum knee flexion angle 0.250.
Discussion: Power spectral density with frequency of 2fω in the perpendicular direction increases when restoring the center of gravity position lowered by Varus Thrust.
Conclusions: The trunk PSD ratio was the best for earlydiagnosis of early knee OA using IMU.
