Fig. 1

Ultrasound examination of the patellar mobility in the superior–inferior direction during isometric knee extension exercise. a The participants were evaluated in a supine position with the knee immobilized with a semi-flexed brace. b An ultrasound probe was fitted onto the skin overlying the patellar tendon in the sagittal plane using water bag kit. c The probe was positioned so that the caudal pole of the patella and the tibia tuberosity were visible within the viewing field. d, e Ultrasound images of the patella, patellar tendon, and tibial tuberosity at rest and during isometric knee extension contraction. The patellar mobility in the superior–inferior direction was measured as the change in distance between manually marked points of the deep insertion to the caudal pole of the patella and tibia tuberosity