Joint Disease as a Cause of Poor Performance
Once a joint has been identified as a problem, the next step is to investigate that joint further to see if there is a major bone problem or whether it is a simple synovitis from a joint sprain. Radiographs of the joint can be very helpful. Often now, a set of radiographs is obtained when a horse starts out on its sporting career as these act as useful reference images if there are problems in the future.
The images may show problems in a joint that would direct us to investigate the joint further. This can be done by performing a bone scan to look at bone turnover associated with margins of the joint, which may help in identifying cracks or stress fractures in the bones adjacent to and thus involving the joint. Bone scans can also be helpful in older horses to investigate problems such as with the hock joint.
MRI is an important way of investigating joints, particularly in the distal limb and hoof regions. A horse that goes sound by blocking the coffin joint may actually have a problem with one or more of the complex ligamentous or tendinous structures, such as the collateral ligaments or the insertion of the deep digital flexor tendon. By correctly identifying the problem, correct therapy and management can be instituted.
Some joints will be investigated surgically using a procedure called arthroscopy. A camera is placed through a keyhole incision into the joint so the articular cartilage within the joint as well as the synovial lining of the joint and any visible ligaments can be assessed. The advantage of this investigative procedure is that any cartilage problems identified can be surgically curetted at the time. Few sport horse joints would need surgery; however in an older horse that is having continued problems with a specific joint, it would be better to operate sooner rather than later. Ultrasound can be used to assess the articular cartilage within some joints, and also the ligaments around the joints. Most of the time when there is a problem with a joint, a simple block to confirm which joint and a few x-rays will suffice.