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Predicting Retrospective Tibial Stress Fractures in Female Runners using Kinematic and Kinetic Variables: 833June 1 9:30 AM - 9:45 AM

Pohl, Michael B.; Davis, Irene S. FACSM

Medicine & Science in Sports & Exercise: May 2007 - Volume 39 - Issue 5 - p S73
doi: 10.1249/01.mss.0000273192.42871.b4
E-17 Free Communication/Slide - Running Mechanics: JUNE 1, 2007 8:00 AM - 10:00 AM ROOM: 263
Free

University of Delaware, Newark, DE

Both kinematics and kinetics of the lower limb have been shown separately to be related to the incidence of tibial stress fractures (TSF) in female runners. Increased hip adduction (HADD) and knee internal rotation (KIR), along with decreased knee adduction (KADD) have been reported in subjects exhibiting tibial stress fractures. In addition, peak tibial shock (PPA), vertical impact load rate (ILR) and peak absolute free moment (FM) have been shown to be higher in these subjects. However, it is currently unknown which kinematic and kinetic variables are the most important in terms of predicting the occurrence of a TSF.

PURPOSE: To determine which kinematic and kinetic factors are the best predictors of tibial stress fractures in female distance runners.

METHODS: Twenty-eight female runners who had previously sustained a TSF along with an age and mileage matched control group (n=28) participated in the study. Subjects ran along a 25m runway at 3.7m/s while kinematic and kinetic data were recorded at 120 and 1080Hz respectively. Five trials from each subject were analysed. The variables HADD, KIR, KADD, PPA, ILR and FM were entered into a binary logistic regression.

RESULTS:

Table

Table

HADD was able to correctly predict whether a subject would fall into the injured or non-injured category 67.3% of the time. Adding FM to the regression equation improved the confidence to identify injured subjects to 78.2%. The inclusion of PPA raised the predictive ability even further to 83.6%. The addition of ILR, KADD and KIR did not further improve the ability to predict injury.

CONCLUSIONS: Based on these results, HADD, FM and PPA appear to be the most important of the variables of interest in terms of predicting TSF in female runners.

© 2007 American College of Sports Medicine