The effect of bracing on patellofemoral joint stress during free and fast walking

Background: Although several studies have demonstrated decreases in patellofemoral pain (PFP) with the application of bracing, the mechanism by which bracing reduces symptoms has not been elucidated. Hypothesis: Individuals who responded favorably to bracing will exhibit decreased patellofemoral stress during level walking. Study Design: Repeated measures, cross-sectional. Methods: Fifteen subjects with a diagnosis of PFP completed two phases of data collection: 1) MRI assessment of patellofemoral contact area and 2) gait analysis. Data were obtained under braced and nonbraced conditions. Variables obtained from both data collection sessions were used as input variables into a mathematical model to quantify patellofemoral stress. Results: Subjects reported a 56% reduction in pain following bracing. Bracing significantly reduced peak stress during free and fast walking (17% and 27%, respectively). The decrease in stress was the result of increased contact area as patellofemoral joint reaction forces were increased following bracing. Conclusion: Bracing resulted in a larger increase in patellofemoral contact area than the increase in joint reaction force, resulting in a decrease in joint stress. Clinical Relevance: The results of this study suggest a possible mechanism by which bracing may be effective in reducing PFP and provides experimental support for the use of this treatment method.