Does Increased Weight Alter Frontal Plane Mechanics In Healthy Controls?

Abstract

Knee osteoarthritis (OA), which contributes to adult disability is strongly correlated with age, weight, and frontal plane biomechanical knee loading. While these factors are important, it is difficult to assess the independent effects of each due to their inherent interrelationships. In addition, there is an elevated incidence of knee OA in females which is associated with increased knee joint loading (knee adduction moment) compared to males. PURPOSE: To examine, during level walking, the relationship between increased weight and gender on frontal plane lower extremity gait mechanics that are related to knee OA progression. METHODS: Fifty-eight (30 male, 28 female) subjects were recruited for the study. All subjects underwent a standard level walking gait analysis in four different weight conditions: normal weight, 10% increased weight, 15% increased weight, and 20% increased weight. The weight conditions were randomized. Weight was distributed evenly in a vest with pockets for that purpose. Walking speed was controlled across conditions. A mixed factor ANOVA (gender x weight) was used to determine statistical significance (p < 0.05). RESULTS: No statistical interactions between gender and weight were observed. The increased weight conditions brought about incremental and statistically significant increases in peak rearfoot inversion moment (p=0.03), peak knee adduction moment during propulsion (p=0.001), plus peak hip adduction moment during weight acceptance (p=0.05) and propulsion (p<0.001). Males exhibited an elevated peak knee adduction moment during weight acceptance (p<0.001) and propulsion (p<0.001), peak knee adduction (p<0.001), peak hip adduction moment during propulsion (p<0.001), peak hip adduction (p<0.001), and hip adduction excursion (p=0.02) in comparison with the females. CONCLUSIONS: Increasing body weight increased lower extremity loading, however, the effect does not differ between males and females. Adding 15% and 20% more mass accounted for the majority of the differences when compared with no weight. Different findings might be observed in patients who have a mass distribution and weight that is more typical of chronic OA development.