IS Case 114: Osteochondral Defect/Dissecans
Imaging Sciences URMC 2008
Publication Date: 2009-05-20
Osteochondral defect is a general term describing a cortical irregularity at the articular surface of long bones. The term encompasses three conditions of similar radiographic appearance including an osteochondral fracture, osteochondritis dissecans (OCD), and spontaneous osteonecrosis. Each condition varies based on pathologic cause and can be distinguished by history.
An osteochondral fracture is an acute fracture of the osteochondral or chondral surface of long bones generally resulting in a bony or cartilaginous fragment and an associated defect at the fracture site. The history of an acute injury can distinguish this condition from osteochondritis dissecans which results from chronic, repetitive injury to the bone. The bony fragment of an osteochondral fracture is vascularized prior to injury whereas the bony fragment of osteochondritis dissecans is avascular. Furthermore, osteochondral fractures occur at weight-bearing surfaces versus osteochondritis dissecans, where the injury most commonly occurs at the lateral femoral notch, a non weight-bearing site.
Spontaneous osteonecrosis generally occurs at weight-bearing sites in adults in their sixth and seventh decades. It is characterized by acute onset of pain with progressive subchondral osteolysis and resultant necrosis. This condition is associated with meniscal injuries and can generally be distinguished by age and history.
OCD as a whole most commonly affects the knees, elbows, and ankles. The prevalence is estimated at 6:10000 in males and 3:10000 in females less than 50 years old. MRI is generally used to evaluate for loose cartilaginous or bony fragments which can cause severe morbidity due to arthritis.
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