Jumper's knee or patellar tendinosis is a chronic insertional injury of the posterior and proximal fibers of the patellar tendon at the site of its origin at the inferior pole of the patella.
Most patellar tendon injuries are the result of repetitive forced extension of the knee as seen in the context of basketball, volleyball, soccer, tennis, and track—hence the name jumper’s knee.
Many authors consider jumper's knee to be the adult form of Sinding-Larsen-Johansson disease 1. Some suggest instead that jumper's knee is a mid-substance patellar tendinopathy.
This form of injury manifests as thickening and partial tearing of the proximal patellar tendon. It is well seen on sagittal MRI as increased tendon thickness greater than 7 mm or as intrasubstance high signal intensity.
Treatment and prognosis
Conservative measures including limitation of activity, followed by exercise and physiotherapy are the mainstays of treatment. Surgical correction is the last option 4.
Differential diagnosis
Imaging differential considerations include:
Osgood-Schlatter disease: occurs at the inferior attachment of the patellar tendon onto the tibial tuberosity
patellar sleeve fractures: same age group; avulsion of inferior pole cartilage, often with small fracture fragment
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infrapatellar bursitis: fluid signal is located anteriorly to the patellar tendon