Sex-dependent differences in ambulatory biomechanics in patients with knee osteoarthritis

We aimed to clarify the sex-dependent differences in ambulatory mechanical loadings including KAM in KOA with adequate consideration of knee pain. To explore the factors leading to large mechanical loadings, the secondary aim was to explore the sex-specific walking pattern such as joint angles related to the loadings.

Seventy-six females and 54 males with medial KOA walked three times at their comfortable speed. Using the data measured by a motion capture system and force plates, the first and second peaks of KAM (KAMp1 and KAMp2, respectively) in addition to the peak of external knee flexion moment (KFM) were computed as indices of the mechanical loadings. KAMs and KFM were compared across males and females using analysis of covariance after adjustment for pain severity as a covariate. We also computed angles of the trunk, hip, knee, and ankle joints and the center of mass (CoM) location at the timings of KAMs and KFM peaks. For the mechanical loadings with sex-related differences, the correlations with joint angles and CoM location were explored in males and females, separately.

Walking speed in females was significantly slower than that in males. No significant difference was found in KFM; however, females displayed significantly larger KAMp1 and KAMp2 than males. In correlation analysis, KAMs were larger with larger knee adduction and ankle abduction angles in both-sex patients. Males with larger KAMs displayed a smaller mediolateral distance between CoM and stance ankle, and females with larger KAMp2 displayed a smaller knee flexion angle. Such walking patterns were not observed in those counterparts. In both sexes, KAMs did not correlate with walking speed, a known factor that increases KAM in healthy adults.

Females with KOA displayed larger KAM than their male counterparts with consideration of knee pain. Such sex-dependent differences in KAM might be induced by the walking patterns including large knee flexion and CoM trajectories during walking.

KOA progression in females may be related to KAM during walking. The development of novel rehabilitation protocols designed to manipulate CoM trajectories and/or knee flexion angle would be an interesting direction to attenuate disease burden in a sex-dependent manner.