Summary Osteochondritis Dissecans is a pathologic lesion affecting articular cartilage and subchondral bone with variable clinical patterns. Diagnosis may be made radiographically (notch view) but MRI usually required to determine size and stability of lesion, and to document the degree of cartilage injury. Treatment may be nonoperative with restricted weight bearing in children with open physis. Surgical treatment may be indicated in older patients (closed physis), lesions that are unstable and patients who have failed conservative management. Epidemiology Demographics juvenile form (open physes) occurs at age 10-15 while the physis is still open adult form (skeletal maturity) Anatomic location knee (most common) posterolateral aspect of medial femoral condyle (70% of lesions in knee) capitellum of humerus talus Etiology Pathophysiology mechanism/etiology may be hereditary traumatic vascular cause of adult form is thought to be vascular pathoanatomic cascade softening of the overlying articular cartilage with intact articular surface early articular cartilage separation partial detachment of lesion osteochondral separation with loose bodies Classification Clanton Classification of Osteochondritis (Clanton and DeLee) Type I Depressed osteochondral fracture Type II Fragment attached by osseous bridge Type III Detached non-displaced fragment Type IV Displaced fragment Presentation Symptoms pain activity related pain that is vague and poorly localized mechanical symptoms indicates advanced disease recurrent effusions of the knee Physical exam localized tenderness stiffness swelling Wilson’s test pain with internally rotating the tibia during extension of the knee between 90° and 30°, then relieving the pain with tibial external rotation Imaging Radiographs recommended views weight-bearing anteroposterior, lateral radiographs obtain tunnel (notch) view knee bent between 30 and 50 degrees MRI useful for characterizing size of lesion status of subchondral bone and cartilage signal intensity surrounding lesion presence of loose bodies Treatment Nonoperative restricted weight bearing and bracing indications stable lesions in children with open physes asymptomatic lesions in adults outcomes 50-75% will heal without fragmentation Operative diagnostic arthroscopy indications impending physeal closure clinical signs of instability expanding lesions on plain films failed non-operative management subchondral drilling with K-wire or drill indications stable lesion seen on arthroscopy performed either transchondral or retrograde outcomes leads to formation of fibrocartilagenous tissue improved outcomes in skeletally immature patients fixation of unstable lesion indications acute, unstable lesion seen on arthroscopy or MRI >2cm in size outcomes 85% healing rates in juvenile OCD chondral resurfacing indications large lesions, >2cm x 2cm knee arthroplasty indications patients > 60 years Techniques Microfracture technique tap awl to a depth of 1-1.5cm below articular surface post-operative NWB for 4-6 weeks with CPM Internal fixation technique options for fixation cannulated screws Herbert screws bone pegs Kirschner wires cons may require hardware removal Osteochondral grafting arthrotomy (vs. arthroscopy) indicated in lesions > 3cm technique open vs. arthroscopic arthroscopy generally used for lesions <3cm arthrotomy used for lesions > 3cm allograft plugs autograft OATS Periosteal patches Prognosis Juvenile form prognosis correlates with age younger age correlates with better prognosis open distal femoral physes are the best predictor of successful non-operative management location lesions in lateral femoral condyle and patella have poorer prognosis appearance sclerosis on xrays correlates with poor prognosis synovial fluid behind the lesion on MRI correlates with a worse prognosis Adult form worse prognosis usually symptomatic and leads to DJD if untreated