Lower extremity biomechanics in those with patellar tendinopathies and the effects of patellar tendon strapping

Abstract

Patellar Tendinopathy (PT) is a common degenerative condition in physically active populations. Knowledge regarding the biomechanics of landing in populations with symptomatic PT is limited. The purpose of this dissertation was to identify the kinematics, kinetics and muscle activation strategies associated with patellar tendinopathies, as well as to assess the effectiveness of patellar tendon straps on altering each of those biomechanical factors. Sixty recreationally active individuals participated in this study. Thirty had current signs and symptoms of PT, including self-reported pain within the patellar tendon during loading activities for at least three months and ≤80 on the Victorian Institute of Sport Assessment Scale-Patella (VISA-P). Thirty healthy participants (Con) with no history of PT or other knee joint pathology were matched to the PT group by gender, age, height, and weight. All participants completed five trials of 40 cm two-legged drop-jumps in patellar tendon strap and no-strap conditions. Kinematics, kinetics and electromyography were recorded. Multiple mixed model two-way ANOVAs were performed to determine the effect of PT status and bracing condition on each of the dependent variables. Participants with PT displayed significantly decreased peak hip (PT=59.2±14.6º, Con=67.2±13.9º, p=.03) and peak knee flexion angles (PT=74.8 ±13.2º, Con=82.5±9.0º, p=.01), as well as decreased maximum angular displacement in the sagittal plane at the hip (PT=49.3±10.8º, Con=55.2 ±11.4, p=.04) and knee joints (PT=71.6±8.4º, Con=79.7±8.3º, p<.001) compared to the control group. When wearing the strap, PT participants reported significantly (p=.03) decreased pain (21.3±20.2mm) compared to the non-strapped condition (28.0±22.1mm). PT participants during the strapping condition had a decreased (p=.05) peak adduction moment (-0.10±0.11 Nmkg-1) compared to controls (-0.17±0.16 Nmkg-1), and no strapping conditions (PT= -0.16±0.16 Nmkg-1, Con= -0.16±0.15 Nmkg-1). The healthy participants with no strap (2.35 ± 1.61%) had a greater rectus femoris peak EMG compared to the control while wearing the strap (2.04 ± 1.35%) and the PT conditions (no strap= 2.09 ± 1.31%, strap=2.18 ± 1.59%). The results indicate that those with PT demonstrate alterations in movement strategies during landings. Moreover, patellar tendon straps appear to reduce pain acutely, possibly through altering lower extremity kinetics.