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Impact of Parity on Gait Biomechanics

Background: Symptomatic knee osteoarthritis (OA) is an incurable condition that affects nearly 50% of adults, and women are twice as likely as men to develop OA. Throughout pregnancy, women experience large changes in morphology and gait mechanics, as well as changes in joint loading. It is possible these adaptations could cause lasting changes postpartum, which may potentially contribute to initiation of OA, thereby increasing the overall risk of OA for women. Purpose: This exploratory study looked to identify differences between lower limb gait mechanics of healthy nulliparous women and healthy parous women. Methods: 28 healthy female participants (14 parous, 14 nulliparous) were recruited for the study. Nulliparous participants had never given birth to a child, and were self-reported not pregnant. Parous participants had given birth to at least one full term infant (37 – 42 weeks) without complications between one to five years before data collection. Kinematic and kinetic data was collected for the lower body, using motion capture and in-ground force plates. Participants completed one quiet standing trial, and walked over-ground through the motion capture space at their preferred, fast, and set walking speeds (1.4 m/s). An ANOVA was performed to test if there were significant differences in between groups. Results: Q angle did not differ between groups. There was a significant main effect of group indicating a larger knee flexion angle at toe off (p = 0.060), smaller knee extension moment at heel strike (p = 0.0006), smaller first peak knee flexion moment (p = 0.040), and smaller peak hip adduction moment for the parous group compared to the nulliparous group (p = 0.003). Conclusions: Our data revealed a decrease in the moments experienced, which could possibly lead to degradation of cartilage due to under loading of the joint. We think this may be an indication that pregnancy could increase risk of OA, and therefore more research into this possibility is warranted.