Diagnosis of Osteochondritis Dessicans
Diagnosis includes a physical examination, x-rays, and/or arthroscopy. A physical examination includes a medical history (information about lameness, joint pain, or family history of OCD) and observation of any abnormalities in stance and gait.
The veterinarian palpates (feels) the joint and tests its range of motion. Anesthesia may be necessary to move the limb without causing pain.
Several signs may be present including:
- Crepitus (crackling noise of bones rubbing against each other)
- Restricted mobility or extension
Osteochondritis Dessicans Testing
Arthrocentesis or joint tap confirms the presence of degenerative joint disease and inflammation. A needle is inserted into the joint, and fluid is withdrawn and analyzed. A high white blood cell count and an opaque consistency of the fluid indicate inflammation; the presence of pus indicates degenerative joint disease caused by infection.
X-rays reveal lesions on bones underneath the cartilage, confirm severe cases of OCD, and show signs of degenerative joint disease, but they do not show separation of cartilage or joint mice. If the animal is lame and the radiographs do not show a lesion, the animal is re-examined within 4 weeks. X-rays are also used to assess whether the joint is properly aligned (joint conformation). Sedation may be required for proper positioning of the limb.
Positive contrast arthrography shows soft tissues, including cartilage. A radioactive dye that provides contrast between tissues and bones is injected and the area is x-rayed. The image reveals thickened or separated cartilage, cartilage flaps, and/or joint mice. This procedure carries the risk for exposure to a high level of radiation.
Arthroscopy is a minimally invasive procedure performed with a fiber-optic tube. For diagnostic purposes, a microscopic camera attached to the tube is inserted into the joint so that the entire joint and abnormalities of bones or soft tissues can be seen. Surgical tools can also be attached in order to take tissue samples and to perform other procedures. This is the diagnostic tool of choice, but it has limited availability.
Osteochondritis Dessicans Differential Diagnosis
Veterinarians must rule out several conditions with similar symptoms, including the following:
- Cartilage fractures
- Elbow dysplasia
- Panosteitis (inflammation of every part of a bone)
Since fragmented medial coronoid process (FMCP) [link to FMCP in elbow dysplasia] and OCD can occur simultaneously, the animal is assessed for this condition.