Patellar tendinopathy (PT) is a common overuse injury in sports that involve jumping and directional changes. The biomechanical differences between individuals with PT and healthy controls during side-cutting, as well as whether both legs are similarly affected, remain unclear. This study aimed to compare the kinematics and kinetics of the affected leg in patients with PT, their unaffected leg, and healthy controls during side-cutting. Methods: Thirty patients with PT and thirty healthy participants performed a side-cutting task. Motion capture and force plates were used to collect data. Five peak ground reaction forces (GRFs) and the corresponding hip, knee, and ankle joint angles and moments were analyzed. Statistical comparisons were performed using t-tests with Bonferroni correction.