Effect of bracing on patellofemoral joint stress while ascending and descending stairs

Objective: To test the hypothesis that individuals who respond favorably to bracing will exhibit decreased patellofemoral joint stress during stair ambulation. Design: A repeated-measures, cross-sectional study. Background: Ascending and descending stairs is one of the most painful activities of daily living for persons with patellofemoral pain (PFP). Although patellar bracing has been shown to reduce symptoms during such tasks, the underlying mechanism has not been identified. Methods: Fifteen subjects with a diagnosis of PFP completed 2 phases of data collection: (1) magnetic resonance imaging to determine patellofemoral joint contact area, and (2) gait analysis during stair ascent and descent. Data were obtained under braced and non-braced conditions. Variables obtained from both data collection sessions were used as input variables into a biomechanical model to quantify patellofemoral joint stress. Results: Although subjects reported an average decrease in pain of 56%, bracing did not reduce peak stress during stair ascent and descent. This finding can be explained by the fact that despite improvements in contact area, bracing resulted in greater knee extensor muscle moments and joint reaction forces. Conclusions: our results do not support the hypothesis that individuals with PFP would demonstrate reduced patellofemoral stress during stair ambulation following the application of a patellar brace. Clinical Relevance: Although bracing did not decrease patellofemoral joint stress during stair ascent and descent, the decrease in pain, increase in quadriceps utilization, and tolerance of joint reaction forces would appear to be beneficial consequences of bracing.