Powers CM, Ward SR, Chan LD, Chen YJ, Terk MR.
PURPOSE: To examine the influence of two patellofemoral braces on pain response,
patellar alignment, and patellofemoral joint contact area in persons with
patellofemoral pain.
METHODS: Fifteen women between the ages of 18 and 45 yr with a diagnosis of
patellofemoral pain participated. After the assessment of pain response using a
visual analog scale, subjects underwent axial plane magnetic resonance imaging of
patellofemoral joint at 0 degrees, 20 degrees, 40 degrees, and 60 degrees of knee
flexion. Imaging was done with the knee extensors contracted (25% body weight)
under three conditions: 1) no brace, 2) On-Track brace, and 3) Patellar Tracking
Orthosis (PTO). Measures of mediolateral patellar displacement and tilt and
medial and lateral facet contact area were obtained from the magnetic resonance
images.
RESULTS: On average, the On-Track brace reduced symptoms by 50%, whereas the PTO
reduced pain by 44%. When averaged across all knee flexion angles, the PTO and
the On-Track brace significantly increased total patellofemoral joint contact
area by 52.0 mm (21%) and 59.3 mm (24%), respectively, when compared with the
no-brace condition. Bracing had no influence on lateral patellar tilt; however,
small but significant changes in lateral patellar displacement were observed.
CONCLUSION: Large changes in pain and contact area occurred without sizable
changes in patellar alignment. The results of this study suggest that changes in
patellar alignment by itself may not be responsible for pain alleviation after
patellar bracing.
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