Osteochondrosis Disease (OCD)
Osteochondrosis Disease (OCD) is a disturbance of cell differentiation in metaphyseal growth plates and joint cartilage. If this condition results in a dissecting flap of articular cartilage with some inflammatory joint changes, it may then be termed osteochondritis dissecans (OCD). This condition is very common in many species. In the dog, medium, large, and giant breeds are affected.
Osteochondrosis is a generalized skeletal disturbance of endochondral ossification in which either parts of the physis (epiphyseal plate) or lower layers of the articular surface fail to mature into bone at a symmetrical rate. This results in focal areas of thickened cartilage that are prone to injury.
Osteochondrosis in the physeal area can result in an ununited anconeal process (UAP), retained cartilaginous cores at the distal ulna, and genu valgum (knock-knee). Osteochondrosis of the articular surface can lead to OCD in several joints (shoulder, stifle, hock, elbow, vertebral articular facets) and possibly to a fragmented coronoid process (FCP) and ununited medial epicondyle of the elbow.
Pathogenesis
The pathogenesis of OCD can be considered as a thickened area of articular cartilage that is not cemented down well to the underlying subchondral bone. Some chondrocytes may die.
Clinical signs
- Lameness
- Often bilateral
- Pain on hyperextension and/or hyperflexion joint
Radiographic Appearance
Normal cartilage is not visible on plain radiography unless significant dystrophic calcification or bone formation has occurred.
- Mineralized cartilage flap
- Joint mouse
- DJD
Treatment
- Rest
- NSAIDs
- Large breed growth diet (reduced Ca intake)
- Time limited feeding (reduced energy intake)
When recognized early (4 to 6 months), some syndromes (OCD of the shoulder, hock, and stifle, retained cartilaginous cores) may be treated with rest and restricted diets.
Once flap formation or separation has occurred, however, healing will not take place.
Removal of the irritating flap or loose piece should be performed as soon as possible. The first objective of surgery is to remove the flap or joint mouse that is irritating the synovium and gouging the opposite cartilaginous surfaces. A second objective is to remove any cartilage in the periphery of the bed that is not adherent to the underlying tissue. A third concern is whether the bed should be curetted. Curettage is sometimes recommended because granulation tissue from the bleeding subchondral bone invades the defect and fills it more quickly with fibrocartilage.