Findings:
- Centered on the stifle join, there is a mild increase in soft tissue opacity.
- Along the cranioproximal margin of the lateral femoral trochlear ridge, a well-defined and irregularly marginated concave defect is identified and associated with moderate subchondral sclerosis. Two, well-defined, sharply marginated mineral fragments are seen along the cranial aspect of the lateral femoral trochlear concave defect.
Note: The tibial tuberosity apophysis closes at approximately 30-36 months of age. This is a normal finding in a 24 month old horse.
Conclusions:
- Osteochondritis dissecans of the lateral trochlear ridge of the distal left femur with associated mild joint effusion/synovial proliferation.
A little bit more…
- Osteochondritis dissecans refers to a disturbance of cellular differentiation in the growing cartilage (Jacquet et al.)
- It is pathologically manifested as dissecting lesions of the cartilage which result in flaps or loose bodies with resulting articular defects (Turner et al).
- OCD is often bilateral and radiographs of the opposite joint should be taken (Jacquet et al., Turner et al.)
- Commonly affected joints (Jacquet et al.):
- Femoropatellar joint – commonly affect the lateral trochlear ridge
- Tarsocrural joint – commonly affect the cranial aspect of the intermediate ridge of the distal articular surface of the tibia
- Shoulder joint
- Metacarpophalangeal joint
- OCD is multifactorial and not yet defined; may be due to (Turner et al.):
- Rapid growth and large body size
- Nutritional: High energy diets, low copper diets, excessive zinc intakes
- Genetics: may be partially inherited
- Hormonal imbalances: insulin and thyroid hormaones
- Bone necrosis secondary to trauma
- Sometimes older horses are diagnosed with OCD incidentally without apparent clinical signs (Jacquet et al.).
- Arthroscopy for debridement of the lesions is the preferred treatment of choice for horses clinically affected. 64% of horses are reported to return to full work after surgery, especially if 3 years of age at the time of the procedure (Foland et al.).
References:
- Jacquet S, Robert C, Walette JP, Denoix JM. Evolution of radiological findings detected in the limbs of 321 young horses between the ages of 6 and 18 months. Vet J. 2013;197(1):58-64.
- Turner S. Diseases of Bones and Related Structures. In: Stashak TS. Adam’s Lameness in Horses, 4th Ed. Lea & Febiger; Philadelphia; 1987:293-485
- Foland JW, McIlwraith CW, Trotter GW. Arthroscopic surgery for osteochondritis dissecans of the femoropatellar joint of the horse. Equine veterinary journal. 1992 Nov;24(6):419-23.
