Jumper's knee is believed to be caused by repetitive stress placed on the patellar or quadriceps tendon during jumping. It is an injury specific to athletes, particularly those participating in jumping sports such as basketball, volleyball, or high or long jumping. Jumper's knee is occasionally found in soccer players, and in rare cases, it may be seen in athletes in nonjumping sports such as weight lifting and cycling.
Investigators have implicated sex, greater body weight, genu varum and genu valgum, an increased Q angle, patella alta and patella baja, and limb-length inequality as intrinsic risk factors. However, the only biomechanical impairment prospectively linked to jumper's knee is poor quadriceps and hamstring flexibility. Vertical jump ability, as well as jumping and landing technique, are believed to influence tendon loading.