(Jumper’s Knee; Sinding-Larsen-Johansson Syndrome)
Infrapatellar tendinitis is an overuse injury to the patellar tendon at the attachment to the lower pole of the patella.
Knee pain with infrapatellar tendon tenderness in physically active children is caused by an overuse syndrome that usually occurs in figure skaters and basketball or volleyball players. It typically affects children 10 to 13 yr. Pain is the most exaggerated when straightening the knee against force (eg, climbing stairs, jumping, doing knee bends).
Etiology of infrapatellar tendinitis is thought to be trauma due to excessive traction by the patellar tendon at its site of origin, leading to microavulsion fractures.
History and physical examination are usually sufficient for diagnosis of infrapatellar tendinitis; however, MRI can show the extent of the injury.
Pain is treated with modification of activities, NSAIDs, and physical therapy. Persistent pain may be treated with surgical repair; however, this is usually not necessary.