Equine orthopedic surgeon Dr. Lawrence R. Bramlage, DVM, of Rood & Riddle Equine Hospital, discusses the treatment and diagnosis of bone chips in ex-racehorse Thoroughbreds.
In the first of quarterly, health Q&As with the internationally renowned Kentucky veterinary practice, the award-winning surgeon, author of 66 referred articles and six book chapters, answers questions about the often highly treatable, common equine injury.
Among his many accomplishments, Dr. Bramlage has been a major contributor to horse medicine and horse-welfare organizations. He has chaired the Grayson-Jockey Club Research Foundation, the largest equine research funding organization in the United States, and has worked as a television consultant for the Breeders Cup and as the on-call vet for the Kentucky Derby.
In the following Q&A with Off-TrackThoroughbreds.com, Dr. Bramlage shares his insights on bone chips, and demonstrates bone-chip surgery in a You Tube video. Later this year, Rood & Riddle veterinarians will also discuss managing weight gain after the track, roarers, and Thoroughbred feet.
Q: What are some of the causes of bone chips in ex-racehorses?
A: Chip fractures in joints, sometimes called osteochondral fragments, are caused by accumulation of micro-damage that first weakens the bone before causing a fragment of bone to separate.
Though chip fractures can occur in any horse, the racehorse is the horse that most often develops a chip, due to the amount of high-speed exercise that can create the chip fractures.
It is not clear why some joints in the same horse will get a chip fracture, while other joints in the same horse show no problems.
Sometimes it can be explained by conformation, which can cause uneven loading of a joint surface, increasing the load and the damage in some areas.
In most instances the bone can respond to the exercise and strengthen itself to prevent chip fractures. In some instances the response is inadequate or too slow and the bone breaks off a small fragment that we see on the radiographs as a “chip fracture.”
Q: How is a bone chip diagnosed and rated in terms of severity, and how are they treated?
A: The presumptive diagnosis is made based on the clinical signs of lameness, increased joint fluid, and response to flexion/manipulation during the exam.
The diagnosis is confirmed by radiographs, which show the damage in the bone.
The degree of severity is a product of the size of the fragment, which is an indication of how much joint surface it damaged, and the location of the fragments— some areas of the joint are more important than others because they carry more weight per square millimeter than other areas.
The best treatment is almost always arthroscopic removal of the fragments. Very large fractures are re-attached with screws. If the chip fracture irritates the joint during exercise, irreversible (degenerative) arthritis and lameness will result.
Q: Does the presence of bone chips necessarily impede an ex-racehorse from becoming a sport horse?
A: It depends on where the fragment is located, how much joint surface is damaged, whether the fragment will do more damage during exercise, and what the hoped-for level of exercise will be.
In some locations such as the top joint of the knee, chip fractures can often be tolerated for all but the highest level of jumping.
In the lower joint of the knee, conversely, chip fractures are troublesome for all but the lightest of trail riding.
So, there is no rule of thumb to use, other than the higher the level of athletic activity the less tolerant the joint will be of any insult.
Your veterinarian is the best source of information on this question as there are many factors, some of which I listed, that need to be considered in this judgment.