Articular Process−Synovial Intervertebral Articulation Complexes in Horses

The articular process-synovial intervertebral articulation complex is located dorsally to the vertebral canal. It is composed of the caudal articular process of one vertebra, the synovial joint (with articular cartilage, synovial fluid and membrane, and articular capsule) located at the base of the interspinal space, and the cranial articular process of the following vertebra. It is also known as the dorsal articular facet joint. Osteoarthritis of this joint has been described radiographically, with a number of different types described, with sclerosis, periarticular new bone, and narrowing of joint space frequently being identified. Commonly two to five joints are affected, usually in the caudal thoracic and cranial lumbar region. In some cases, there will be abnormal nuclear scintigraphic uptake of the region, which can aid with diagnosis. Further ultrasonographic abnormalities can be identified, particularly relating to periarticular osteophytes and proliferation. Treatment and management include periarticular ultrasonographic-guided injections of steroids, use of NSAIDs, and rehabilitation using exercise protocols after progressive warm-up at a slow canter.