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The separation of articular cartilage and subchondral bone fragment from a joint surface was misnamed as osteochondritis dissecans in the nineteenth century in the false belief that there was an underlying inflammatory pathology. We know now that this is not the case but the name has stuck. The separated fragment may become avascular and exist as a loose body within the joint. It is the most common cause of a loose body in the joint space of adolescent patients.
There are two main types of osteochondritis dissecans:
- Adult form (after the physis has closed).
- Juvenile form (occurring with an open epiphyseal plate).
Some believe that the adult form represents undiagnosed, persistent disease from childhood. The aetiology is uncertain but thought to be due to a multifactorial combination of:
- Genetic predisposition
- Repetitive trauma
- Abnormal ossification
- Ligamentous laxity
- Biomechanical factors
This is a rare disorder, most often affecting the knee. The exact incidence is unknown but there are approximately 3-6 cases per 10,000 adult population and males are affected more often than females.
- It most commonly affects the knee joint (75% of cases). About 85% of knee lesions are on the medial femoral condyle.
- The elbow and ankle are the next most common joints affected. In the elbow, it affects the capitellum of the humerus and, in the ankle, it affects the talar dome.
- Very rarely it affects articulations of the shoulder, hand, wrist or hip.
- The disease can affect more than one site and may be bilateral in 20-30% of cases.
- Trauma (about half of cases).
- Male sex (although incidence is increasing in women and girls).
- Overuse due to sporting activity.
- Familial pattern in about 10% of cases.
- Ligamentous weakness.
- Genu valgum/varum.
- Meniscal lesions in the knee.
- It usually presents in teenage years or the early 20s.
- It can affect younger children who are very active in sports.
- It may only become symptomatic in later life.
- Around 5% of middle-aged patients with osteoarthritis of the knee are thought to have suffered osteochondritis dissecans in earlier life.
- The usual feature is vague, aching joint pain and swelling worsened by activity.
- Locking, catching and giving-way may be present, particularly with intra-articular loose bodies.
- When the lateral femoral condyle is affected, patients commonly feel a painful 'clunk' when flexing or extending the knee.
- In most cases, there is a full range of movement in the joint without signs of ligamentous instability. Joint effusion is often present, particularly if there has been trauma.
- With medial femoral involvement, external tibial rotation when walking is typical.
- With the knee fully flexed, it should be possible to palpate the area directly on the articular cartilage of the medial femoral condyle, which is usually tender.
- Wilson's sign has been used for demonstrating the presence of a medial femoral condyle lesion, although its diagnostic merit has been challenged by some:
- With the knee flexed to 90° and the tibia internally rotated, gradual extension of the joint leads to pain at about 30°.
- External rotation of the tibia at this point relieves the pain.
Early diagnosis is vital. Clinical findings can be subtle so have a low threshold for ordering X-rays or requesting an orthopaedic opinion. Juvenile lesions are typically stable, with an intact articular surface, and thus have the potential to heal with conservative management if detected early.
Alternative causes of the symptoms should be sought where there is no radiological confirmation of osteochondritis dissecans. Consider:
In children and adolescents, traction apophysitis - eg, Osgood-Schlatter disease - may cause similar symptoms but the pain is usually localised to the relevant tendinous insertion with overlying tenderness and swelling.
- X-ray shows a subchondral crescent sign or loose bodies. For the knee, request anteroposterior, lateral and tunnel (with knee in flexion) views.
- Ultrasound may be useful, cost-effective and provide dynamic scanning with motion of the affected joint.
- CT demonstrates the size and site of the lesion.
- MRI is best for evaluation of overlying cartilage and is used to stage and assess stability of the lesion, which will determine subsequent management. It is also useful for prognosis.
- Scintigraphy may show increased uptake in the fragments. Osteoblastic activity is used to guide treatment since it relates to a greater chance of healing with conservative treatment.
|Staging of Osteochondritis Dissecans|
|Stage||Appearance on MRI||Stability of lesion|
|I||Thickening of articular cartilage and low signal changes.||Stable|
|II||Articular cartilage interrupted, low-signal rim behind fragment showing that there is fibrous attachment.||Stable|
|III||Articular cartilage interrupted, high signal changes behind fragment and underlying subchondral bone.||Unstable|
Conservative measures should be used to treat stable (Grades I and II) lesions and younger patients with open epiphyses. Many cases will resolve with this regimen including:
- Stopping sport/precipitating activities for 6-8 weeks.
- Gentle physiotherapy.
- Immobilisation, protected weight bearing and bracing, which are advocated by some.
- Reassessment at three months and, if asymptomatic, allowing the patient to self-monitor the condition.
Simple analgesics or non-steroidal anti-inflammatory drugs (NSAIDs) may be used to treat pain. NSAIDs will not affect the disease course as there is no significant inflammatory component.
Surgery is usually undertaken when:
- Conservative management has failed.
- The lesion is unstable (Grade III).
- Loose bodies are present (Grade IV).
Surgical approaches include:
- Arthroscopic subchondral drilling to promote revascularisation.
- Arthroscopic debridement and fragment stabilisation.
- Arthroscopic excision, curettage, and drilling.
- Open removal of loose bodies, reconstruction of the crater base and potential replacement with fixation.
- Bone grafting and autologous chondrocyte transplantation.
- Chronic pain
- Functional impairment
- Prognosis depends on the age of the patient, the affected joint and the stage of the lesion at presentation.
- Younger patients with small, stable medial femoral condyles have the best prognosis. 
- Unstable lesions can heal after stabilisation, but long-term prognosis is not clear. Chronic loose fragments can be difficult to fix and tend to heal poorly.
- Excision of large lesions from weight-bearing zones also tend to give poor results.
Further reading & references
- Cooper G et al; Osteochondritis Dissecans, Medscape, Oct 2012
- Hixon AL, Gibbs LM; Osteochondritis dissecans: a diagnosis not to miss. Am Fam Physician. 2000 Jan 1;61(1):151-6, 158.
- Conrad JM, Stanitski CL; Osteochondritis dissecans: Wilson's sign revisited. Am J Sports Med. 2003 Sep-Oct;31(5):777-8.
- Kocher MS, Tucker R, Ganley TJ, et al; Management of osteochondritis dissecans of the knee: current concepts review. Am J Sports Med. 2006 Jul;34(7):1181-91.
- Emmerson BC, Gortz S, Jamali AA, et al; Fresh osteochondral allografting in the treatment of osteochondritis dissecans of the femoral condyle. Am J Sports Med. 2007 Jun;35(6):907-14. Epub 2007 Mar 16.
- Pascual-Garrido C, Moran CJ, Green DW, et al; Osteochondritis dissecans of the knee in children and adolescents. Curr Opin Pediatr. 2013 Feb;25(1):46-51. doi: 10.1097/MOP.0b013e32835adbf5.
- Murray JR, Chitnavis J, Dixon P, et al; Osteochondritis dissecans of the knee; long-term clinical outcome following arthroscopic debridement. Knee. 2007 Mar;14(2):94-8. Epub 2007 Jan 10.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr Chloe Borton
Dr Colin Tidy
Dr John Cox