Do kinematic behaviors of the pelvis and trunk during single-leg standing reflect the peak knee adduction moment of during walking?

Background: A high external knee adduction moment (KAM) during walking is known as one of the risk factors for progression of knee osteoarthritis (KOA). In the clinical practice, it is important to find a convenient method that can predict aKAMduringwalking in patientswithKOA.Wehave then hypothesized that kinematic behaviors of the pelvis and the trunk during single-leg standing could reflect the peak KAM during walking. Purpose: The purpose of the present study was to investigate the relationship between kinematic behaviors of the pelvis and the trunk during single-leg standing and the peak KAM during walking in the healthy subjects. Methods: Twenty-eight healthy subjects were recruited for this study (23.6± 4.0 years). These subjects performed the gait and the single-leg standing trials. In the single-leg standing trial, subjects stood on two force platforms. The subjects lifted one lower limb off the force plate ‘as fast as possible’ following a sonic cue, and held the posture. The onset of lift-off point (lift-off onset) was defined as the time when the vertical component of the ground reaction force becomes less than 10N. All data were recorded during the period from a ‘sonic cue’ until 1000ms following the lift-off onset. In the gait trial, subjectswalked at a self-selected speed. The data were collected with a six-camera motion analysis system and two force plates that were time synchronized and sampled at 200Hz and 1000Hz, respectively. Helen Hays marker set with additional markers placed on the spinous processes of C7 and S1 was used. The peak KAM during the walking and the single-leg standing were determined using the SIMM6.0.2 software. The maximum andminimum value of the lateral lean angle of the trunk and the lateral tilt angle of the pelvis during single-leg standing were calculated using the custom Matlab code. The trunk lean toward the swing limb side and the contralateral pelvis drop were denoted as a negative angle. Pearson correlation coefficients were used to determine a relationship between the KAM gait and the other variables during SLS. The level of significance was set at 0.05. Results: The peak KAM during single-leg standing was significantly correlated with that during walking (r= 0.40, p= 0.03). The peak KAM during walking was significantly correlated with the maximum value of the lateral lean angle (r=−0.45, p= 0.02) and lateral tilt angle of the pelvis (r=−0.40, p= 0.04) during single-leg standing. Conclusion(s): The present study showed that the lateral lean angle of the trunk and the lateral tilt angle of the pelvis during single-leg standing reflect the peakKAMduring walking. Implications:Findings of the present study indicate a possibility that kinematic behaviors during a single-leg standing task can predict a peak KAM during walking in the KOA patients.