osteochondral defect

Osteochondral defects (OCD) or lesions (OCL) are focal areas of damage with articular cartilage damage and injury of the adjacent subchondral bone plate and subchondral cancellous bone.

Terminology

Osteochondral defect is a broad term that describes the morphological change of a localized gap in the articular cartilage and subchondral bone . It is often used synonymously with osteochondral injury/defect and in the pediatric population. Isolated lesions of cartilage or subchondral bone are not considered an OCD .

Please note that OCD is a commonly used abbreviation for both osteochondral defect and osteochondritis dissecans, two closely related conditions.

Pathology

Etiology
Location

The recognized sites of osteochondral defects are:

Staging

Osteochondral injuries are graded according to the stability and location of the fragment and presence of secondary degenerative changes (see: osteochondral injury staging).

Radiographic features

Plain radiograph and CT

Both x-rays and CT are able to detect displaced defects with ease. However, they are insensitive to grading lower stage lesions and are inadequate in predicting stability.

MRI

MRI is the modality of choice, with high sensitivity and specificity for the detection of separation of the osteochondral fragment (see: osteochondral injury staging and osteochondritis dissecans surgical staging). This is essential in determining management.

  • T1
    • the signal is variable with intermediate to low signal adjacent to fragment and variable fragment signal
  • T2
    • high signal line (rim sign) demarcating fragment from bone usually indicates an unstable lesion, however, false positives can result from edema
    • low signal loose bodies, outlined by high signal fluid
    • donor defect filled with high signal fluid
    • high signal subchondral cysts

Treatment and prognosis

Treatment depends on the location and size of the defect as well as the presence of secondary degenerative changes. When the latter is present, then joint replacement is often the only feasible treatment.

At earlier stages (stage 1 to 4), a number of options exist including: