Biomechanical effects of patellar taping in subjects with patellofemoral pain syndrome (PFPS).
Patellofemoral pain syndrome (PFPS) is one of the most common musculoskeletal disorders affecting adults. Patellar taping provides an effective treatment in alleviating the symptoms of a high proportion of subjects who present with PFPS. However, the mechanisms of pain reduction have not been established. The aim of this work was to evaluate the effects of patellar taping on the biomechanics of the patellofemoral joint and level of pain in PFPS subjects, during the eccentric phase of single leg squatting at 30° of knee flexion. These were determined with a combined kinetic and kinematic approach using data from video analysis, force plate and EMG. A series of pilot tests was performed, involving a group of asymptomatic volunteers performing a number of knee flexion procedures. These tests demonstrated a high reliability in both the estimated patellofemoral joint reaction force (PFJRF) and relative amplitude of vasti, but less impressive reliability for the parameters associated with muscle onset. The main case-controlled study involved 18 PFPS subjects, recruited from a local Physiotherapy Department, and a similar number of healthy controls. The test procedure was performed on the knees of both subject groups and, where appropriate, during and after patellar taping. The results revealed that the mean value of PFJRF, which was 2025 N prior to taping, had decreased significantly to 1720 N (p< 0.05) following a period of taping and exercises which lasted between 2-5 weeks. Equivalent changes were also recorded with the pain levels, although the ratio of the amplitude of the vasti did not change during this period. The only significant differences between the two subject groups were with the relative timing of muscle onset, for which VMO preceded VL in the healthy controls. The reduction of biomechanical characteristics following the application of patellar tape and exercises in PFPS subjects, may explain the mechanism of pain reduction during the early phase of single leg squatting.
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