The influence of patellar bracing on patellar and knee load-distribution and kinematics: an experimental cadaver study

Abstract

The aim of this study was to analyze the biomechanical consequences of patella bracing in order to evaluate possible mechanisms supporting its clinical application. The hypothesis is that the patellar bracing reduces patellofemoral pressure by influencing patellar and knee kinematics, and load distribution. Physiologic isokinetic knee extension motions were simulated on ten human knee cadaver specimens using a knee kinematic simulator. Joint kinematics were evaluated using an ultrasound-based motion analysis system and patellofemoral contact pressure was measured using a thin-film piezoresistive pressure measuring system. Infrapatellar tissue pressure was analyzed using a closed sensor-cell. Three different patella braces were fitted to the knee cadavers and their influence on the kinematic and kinetic biomechanical parameters were evaluated and compared to the physiologic situation. Patellar bracing resulted in a significant (p = 0.05) proximalization of the patella up to 3 mm. Depending on the type of brace used, a decrease in the infrapatellar fat pad pressure was found and the patellofemoral contact area was decreased significantly (p = 0.05) between 60 degrees of knee flexion and full extension (maximum 22%). Patella bracing significantly (p = 0.05) reduced the patellofemoral contact pressure an average of 10%, as well as the peak contact pressure which occurred. Patellar bracing significantly influences patella biomechanics in a reduction of the patellofemoral contact area and contact pressure as well as a decrease in the infrapatellar tissue pressure. The application of infrapatellar straps is suggested for the treatment and prevention of anterior knee pain, especially in high level sports.

Effect of bracing on dynamic patellofemoral contact mechanics

“…However, symptomatic patellofemoral joints likely have a reduced capacity to tolerate loading [4], and loads that would not have caused injury in an uninjured joint may cause further injury to a symptomatic patellofemoral joint, creating a vicious cycle of loading and injury over time. Treatments such as bracing, infrapatellar straps, and taping are primarily aimed at correcting patellofemoral maltracking [12][13]24] or improving control of the joint through proprioceptive feedback [28]. However, the implied hypothesis is that correcting maltracking and improving joint control have the additional benefit of decreasing contact pressure in the patellofemoral joint [24,39].…”

“…Treatments such as bracing, infrapatellar straps, and taping are primarily aimed at correcting patellofemoral maltracking [12][13]24] or improving control of the joint through proprioceptive feedback [28]. However, the implied hypothesis is that correcting maltracking and improving joint control have the additional benefit of decreasing contact pressure in the patellofemoral joint [24,39]. Knee sleeves are commonly considered the simplest form of a knee brace, as they simply provide a compressive force to the entire knee joint.…”

“…Contact area and pressure were measured using a 33 × 28 mm piezoresistive electronic pressure measuring film (K-Scan #4000, Tekscan Inc; Boston, Massachusetts) [24,31]. Each sensor was individually calibrated on a custom materials-testing system.…”

“…While previous studies have reported decreases in lateral patellar translation with bracing under static conditions [21][22][23] and decreased contact pressure and proximal shift of the patella with the application of infrapatellar straps [24], some studies have shown no effect on patellar alignment with bracing [25]. One recent study reported that bracing decreased both lateral tilt and translation of the patella during dynamic loading [12], and subjective improvements in knee stability and pain have been reported with bracing [8,20,26].…”

Patellar Tendon Straps Decrease Pain and May Alter Lower Extremity Kinetics in Those With Patellar Tendinopathy During Jump Landing

“…7 However, there is a lack of evidence of the strap's efficacy and mechanisms by which strapping reduces patellar pain. 4,[8][9][10] The patellar tendon strap is thought to exert compressive pressure on the damaged tendon and, via an unknown mechanism(s), alleviate internal tensile strain and loading created by quadriceps and tibial forces, thus reducing pain.…”