The sacroiliac (SI) joint is a synovial articulation.

 

By Ronen Hoikhman MRCVSRonen Hoikhman MRCVS

The ilium is the largest, fan-shaped bone of the pelvis, and the sacrum, which is also considered part of the pelvis, is made up of five fused vertebrae that form one solid unit just before the tail. Two SI joints connect these bony structures, and a series of ligaments along the central aspect of the joints hold those joints together. This joint functions in pelvic attachment to the skeleton, providing support during weight bearing and helping to transfer propulsive forces of the hindlimb to the vertebral column.The sacroiliac (SI) joint is a synovial articulation. The ilium is the largest, fan-shaped bone of the pelvis, and the sacrum, which is also considered part of the pelvis, is made up of five fused vertebrae that form one solid unit just before the tail. Two SI joints connect these bony structures, and a series of ligaments along the central aspect of the joints hold those joints together. This joint functions in pelvic attachment to the skeleton, providing support during weight bearing and helping to transfer propulsive forces of the hindlimb to the vertebral column.

The prevalence of SI joint injuries in performance horses is probably high, and many go undiagnosed. When SI disease begins, it can affect one or several structures within the region. Ligaments can be torn, stretched, or otherwise damaged, and the bones can show arthritic changes. When the damage goes on for a long time, it creates arthritis in the joints because they are not sufficiently supported by the attaching ligaments. SI disease can appear in any age and it is often the compounding result of an injury, plus wear. One of the most common concurrent injuries is to the top of the hind suspensory ligaments, that runs down the back of each cannon bone. This Injury causes an alternation in the horse’s movement due to the pain, which in turn puts stress on the SI joints, resulting in an injury. Similarly, conformation can be the primary cause. The method of training can also contribute to the disease, as we put more emphasis on one discipline.

CLINICAL PRESENTATION

Horses with sacroiliac joint injuries vary in clinical presentation, usually based on the duration and extent of the injury present. When following a traumatic injury, local soreness and lameness can often be noted. Asymmetry can also be seen, however the most consistent clinical features in chronic sacroiliac injuries is a prolonged, nonprogressive history of reduced or poor performance. Studies have shown that Warmbloods involved in dressage and show jumping were most affected. Changes in performance included back stiffness, unwillingness to work, lack of impulsion fromnonprogressive history of reduced or poor performance. Studies have shown that Warmbloods involved in dressage and show jumping were most affected. Changes in performance included back stiffness, unwillingness to work, lack of impulsion fromone or both hindlimbs and refusing jumps. To many observers the horse can appear clinically normal. It is important to note that lameness is not seen in most cases, however subtle gait asymmetry may be noticeable at slow speeds during groundwork or dressage movements. Signs are often markedly accentuated when the horse is ridden, especially with changes in direction through tight circles in trot, half passes or flying lead changed in canter. Conflict behaviour is also one of the common signs.

DIAGNOSIS AND TREATMENT

The diagnosis of SI diseases can be very challenging, as this joint is not well accessible. Palpation of the area in many cases does not trigger the pain and many times there is no lameness or there is a concurrent problem. Your veterinary surgeon will evaluate the horse and eliminate other potential sources of pain by different diagnostic methods before suspecting an SI joint disease; thereafter bone ultrasonography can be used to aid diagnosis, but the most frequently method used today is a bone scan. The treatment is mostly symptomatic to gain control over the condition with a long-term physical rehabilitation program.

If you are at all concerned about your horse’s heart please contact your vet.

Veterinary advice in this magazine is provided as a general guide Veterinary advice in this magazine is provided as a general guide and you should always seek professional advice.

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