Powers CM, Ward SR, Chen YJ, Chan LD, Terk MR.
To test the hypothesis that individuals who respond favorably to
bracing will exhibit decreased patellofemoral joint stress during stair
A repeated-measures, cross-sectional study.
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.
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.
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.
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.
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.
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