Clinical history A 22 year old Arabian mare presented with acute lameness in the right hind limb - pain was evident on palpation of the stifle joint. Radiographs were made of both stifle joints. Right Left Radiographic changes
- Cystic lesions in the medial condyle bilaterally, larger on the right
- The cysts involves the subchondral bone causing a flattening of the articular surfaces
- Periarticular osteophytes medially, more prominent on the right
- Subchondral sclerosis in the tibial plateau, more prominent on the right
- Intra-articular mineralization medially, seen on the right
Radiographic diagnosis Femoral condylar cystic lesions with articular component (osteochondrosis) with secondary changes of arthrosis. Problem - how to attribute the acute clinical signs of lameness seen on one pelvic limb to a bilateral developmental lesion in a 22 year old mare - ??? Enlarged studies - note the calcified tissue (arrows) on the right stifle Comments The failure of endochondral ossification leads to necrosis in the basal layers of the thickened retained cartilage - this can lead to subchondral bone cyst formation. The diagnosis of OCD plus secondary arthrosis is correct but probably not the cause of the acute clinical signs. Ultrasound examination of the joint showed severe injury to the medial meniscus - this was thought to be a diagnosis that more closely matched the clinical signs.
