Patellar tendinitis

Patellar tendinitis (patellar tendinopathy, also known as jumper's knee and Sinding-Larsen-Johansson disease), is a relatively common cause of pain in the inferior patellar region in athletes.

Presentation

It begins as inflammation in the patellar tendon where it attaches to the patella and may progress by tearing or degenerating the tendon. Patients present with an ache over the patella tendon. Most patients are between 10 and 14 years old. Magnetic resonance imaging can reveal edema (increased T2 signal intensity) in the proximal aspect of the patellar tendon.

Causes

It is an overuse injury from repetitive overloading of the extensor mechanism of the knee. The microtears exceed the body's healing mechanism unless the activity is stopped.

The injury occurs in many athletes, but is most common in sports such as; baseball (catcher), bowling, golf (reading putts), soccer, rugby, volleyball, track & field, freerunning, parkour, American football, basketball, or gymnastics which require explosive movements.

Treatment

Early stages may be treated conservatively. Currently this involves eccentric loading, a form of physiotherapy. Should this fail, autologous blood injection, or injection of platelet rich plasma may be performed and is typically successful.  Uncommonly it may require surgery to remove myxoid degeneration in the tendon. This is reserved for patients with debilitating pain for 6–12 months despite conservative measures. Novel treatment modalities targeting the abnormal blood vessel growth which occurs in the condition are currently being investigated.

References

• Jumper's Knee by Bridget Mikysa, M.D., University of Washington Department of Radiology
• Kaplan, Helms, Dussault, Anderson, and Major Musculoskeletal MRI 2001 .
• Khan KM, Bonar F, Desmond PM, et al. (1996). "Patellar tendinosis (jumper's knee): findings at histopathologic examination, US, and MR imaging. Victorian Institute of Sport Tendon Study Group". Radiology 200 (3): 821–7. PMID 8756939. http://radiology.rsnajnls.org/cgi/pmidlookup?view=long&pmid=8756939. 
• Kettunen JA, Kvist M, Alanen E, Kujala UM (2002). "Long-term prognosis for jumper's knee in male athletes. A prospective follow-up study". Am J Sports Med 30 (5): 689–92. PMID 12239003. http://ajs.sagepub.com/cgi/pmidlookup?view=long&pmid=12239003. 
• Tom Crisp, Faisal Khan, Nat Padhiar,et al. (2008). "High volume ultrasound guided injections at the interface between the patellar tendon and Hoffa's body are effective in chronic patellar tendinopathy: A pilot study.". Disability and rehabilitation. 30: 1625–34. doi:10.1080/09638280701830936. PMID 18608403. 

External links

• The KNEEguru - educational site packed with knee content with sections on patellar problems
• Jumpers Knee & Acrobatics
• Patellar Tendinitis, Musculoskeletal Consumer Review
• Ultrasound images demonstrating patella tendinosis and an autologous blood injection