Effect of bracing on dynamic patellofemoral contact mechanics

Decreases in patellofemoral pain have been demonstrated with bracing; however, the mechanisms of pain reduction remain unclear. Our purpose was to evaluate the hypothesis that patellofemoral bracing decreases peak pressure on the retropatellar surface through an increase in patellofemoral contact area. Nine cadaveric knees were tested during simulated free-speed walking with no brace, a knee sleeve, two different patellar stabilization sleeves, and a wrap-style patellar stabilization brace. Contact area and pressure were measured using a dynamic pressure sensor located in the patellofemoral joint. For the unbraced knee, contact area and peak pressure varied with knee flexion angle, ranging from 0.30 ± 0.3 cm(2) and 1.80 ± 1.7 MPa at full extension to 2.28 ± 0.5 cm(2) and 4.19 ± 1.7 MPa at peak knee flexion. All braces increased contact area, while the wrap-style brace decreased peak pressure (p < 0.001). Sleeve braces compress the quadriceps tendon causing the patella to engage the trochlear groove earlier during knee flexion. The wrap-style brace reduced peak pressure by shifting the location of highest pressure to a region with increased articular cartilage thickness. Sleeve braces may be useful for treatment of patellar subluxation disorders, while wrap-style braces may be effective for treatment of disorders associated with degenerative cartilage changes.