Lower extremity kinematics during a drop jump in individuals with patellar tendinopathy

Background: 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, but altered mechanics may play a role in the development or perpetuation of PT. Purpose: To identify whether study participants with PT exhibited different landing kinematics compared with healthy controls. Study Design: Controlled laboratory study. Methods: Sixty recreationally active participants took part in this study, 30 had current signs and symptoms of PT, including self-reported pain within the patellar tendon during loading activities for at least 3 months and ≤80 on the Victorian Institute of Sport Assessment Scale-Patella (VISA-P). Thirty healthy participants with no history of PT or other knee joint pathology were matched by sex, age, height, and weight. Participants completed 5 trials of a 40-cm, 2-legged drop jump followed immediately by a 50% maximum vertical jump. Dependent variables of interest included hip, knee, and ankle joint angles at initial ground contact, peak angles, and maximum angular displacements during the landing phase in 3 planes. Independent-samples t tests (P ≤.05) were utilized to compare the joint angles and angular displacements between PT and control participants. Results: Individuals with PT displayed significantly decreased peak hip (PT, 59.2° ± 14.6°, control, 67.2° ± 13.9°, P =.03) and knee flexion angles (PT, 74.8° ± 13.2°, control, 82.5° ± 9.0°, P =.01) compared with control subjects. The PT group displayed decreased maximum angular displacement in the sagittal plane at the hip (PT, 49.3° ± 10.8°, control, 55.2° ± 11.4°, P =.04) and knee (PT, 71.6° ± 8.4°, control, 79.7° ± 8.3°, P <.001) compared with the control group. Conclusion: Participants with PT displayed decreased maximum flexion and angular displacement in the sagittal plane, at both the knee and the hip. The altered movement patterns in those with PT may be perpetuating symptoms associated with PT and could be due to the contributions of the rectus femoris during dynamic movement. Clinical Relevance: Based on kinematic alterations in symptomatic participants, rehabilitation efforts may benefit from focusing on both the knee and the hip to treat symptoms associated with PT.