Effect of bracing on dynamic patellofemoral contact mechanics

Abstract

Abstract-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 freespeed 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.

A clinical study of the biomechanics of step descent using different treatment modalities for patellofemoral pain

“…It has previously been reported that patients with patellofemoral pain display altered or compensatory movement patterns when descending from a step [13,14,16,29,30]. This phenomenon was also observed in this study, manifested by an increased amount of medial/lateral displacement or 'wobble' of the knee and in some cases, of the trunk and upper limbs.…”

“…It is therefore possible that this contributed to the mechanical stability of the patella as it tracked in the femoral trochlear groove during the step descent. Patella sleeve braces, of the type used in this study, have been shown to cause the patella to engage in the trochlear groove earlier during flexion through their compressive mechanism on the quadriceps tendon [29]. This could also have contributed to the improved stability observed in this study.…”

“…a larger contact area should result in a lower joint pressure. However, this is an area of some controversy as recently it has been demonstrated that patella sleeve braces although increasing patellofemoral contact area, also increased joint pressure [29]. The brace contained a lateral buttress that was pulled medially by the direction of the straps.…”

Patellofemoral pain: an update on diagnostic and treatment options

“…If the response is positive from patellar taping, it may also be positive with a lateral buttress knee brace. Sleeve braces have been shown to help with patella tracking while wrap-style braces reduce peak patellofemoral pressure by changing the location of contact and pressure [35]. However, a recent randomized trial evaluating the use of bracing for patellofemoral pain associated with arthritis found no clinical benefit for bracing [36].…”

Is the effectiveness of patellofemoral bracing modified by patellofemoral alignment and trochlear morphology?

“…Patellar bracing provides certain advantages over taping, including longer equipment life due to reusable materials, and lack of possible allergic dermatitis to adhesives. As bracing provides similar biomechanical effects as taping, such as increasing joint contact area [9], it should similarly reduce symptoms, but the results thus far have been more conclusive for the use of bracing in patellar instability, and less convincing for PF OA [6, 10]. …”