Jumper's knee (i.e., patellar tendinopathy or patellar tendinitis) is injury/inflammation at the patellar tendon attachment to the kneecap resulting from jumping.
Causes
Jumper's knee is typically seen in sports related activities such as basketball and volleyball where athletes jump and land on hard surfaces. Chronic repetitive distractive forces at the patellar tendon attachment to the patella produces micro-tearing and inflammation. If left untreated, bone avulsions from the inferior patella, macroscopic tearing of the patella, and inflammation of Hoffa's fat pad (fat pad cushion behind the kneecap) may also occur.
Symptoms
Anterior knee pain and tenderness localized to the inferior patella (kneecap). The pain is worse with jumping, walking, and running.
Diagnosis
A physical exam by a doctor is performed to evaluate for anterior pain and tenderness. X-ray may be performed to exclude a bone avulsion injury of the patella or a patellar fracture. An MRI will show partial tearing or inflammation at the posterior central origin of the patellar tendon origin and often edema in the adjacent anterior knee fat pad (i.e. Hoffa's fat pad). MRI is also helpful to rule out other injuries including chondromalacia patella, patellofemoral arthritis, patellar tracking disorders, quadriceps fat pad impingement, synovitis, and meniscus tears which could contribute to the knee pain.
The term jumper's knee is used for adults while Sinding-Larsen-Johansson disease, a related condition or subtype of jumper's knee, is seen in active children between 10 and 14 years old.
Treatments
Treatment is conservative and includes rest, icing, NSAIDS, and stretching exercises.