Is Dynamic Hip And Knee Malalignment Associated With Tibial Stress Fracture In Female Distance Runners?

Abstract

It has been suggested recently that running injuries in females may be related to dynamic hip and knee malalignment in the frontal and transverse planes. Specifically, increased hip adduction (HADD), hip internal rotation (HIR) and knee abduction (KABD). Altered alignment of the lower extremity may predispose a runner to injury by changing load distribution. Since tibial stress fractures (TSF) are load-related injuries, differences in stance limb alignment may contribute to the risk of injury. PURPOSE To determine whether the occurrence of TSF is associated with dynamic malalignment of the hip and knee. It was hypothesized that runners who had sustained a TSF previously would exhibit increased HADD, HIR and KABD and altered axial rotation at the knee (KIR, KER), compared to runners with no history of fracture. The utility of foot abduction angle (FTLAB) as a simple surrogate measure of hip and knee malalignment was also tested. METHODS Healthy runners who had sustained TSF previously (n = 22) and an age and mileage matched control group (n = 22) participated. Gait data were collected at 120 Hz as subjects ran at 3.7m/s on a 25m runway. Data from five trials were averaged for analysis. Independent t-tests were used to investigate the hypothesized differences between the groups (one-tailed for HADD, HIR and KABD). RESULTS (All values in degrees: adduction, internal rotation positive; abduction, external rotation negative.)TableThese data support our hypotheses that runners with a history of tibial stress fracture have higher frontal plane HADD and KABD angles. In the transverse plane, only KIR shows an increase. Based on these data, dynamic hip and knee malalignment may play a role in stress fracture injuries in female runners. FTLAB does not differ between the groups, so is unsuitable as a simple surrogate measure of proximal joint alignment. CONCLUSIONS: HADD, KABD and KIR are increased in runners with a history of tibial stress fracture compared to a control group. Prospective studies are needed to determine whether increases in these angles during running are predictive of stress fracture injury.