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Dislocated Knee Cap

November 26, 2012

A dislocated knee cap doesn’t have to be career ending for your horse, but you’ll need some additional information to decide your next step.

Ask an ExpertQuestion:

My 2 1/2-year-old Quarter Horse gelding has dislocated his knee cap. My veterinarian said it is from a possible slip/sudden twist that could have caused the problem. He is not lame or experiencing severe pain. The knee cap slips out of position when placed back in position. The course of action is 10cc of anti-inflamatory for five days and stall rest. His training has been ground manners and ponying with a reliable trail horse. He has carried a saddle, but never had weight on his back. Is surgery down the road for him? What are his chances of being more than a pasture ornament? I will keep him as that if that is what will keep him healthy.

For the answer to this question, the American Association of Equine Practitioners consulted Dr. Chris Bell.


Thanks for the interesting question. Luxation (dislocation) of the patella (knee cap) is fairly rare in Quarter Horses. It is seen more commonly in miniature horses and ponies. The cause is often related to an anatomical abnormality in the end of the femur bone (part of the stifle joint). It is good that your horse is not in pain and able to move around normally. Once the five-day prescribed course of anti-inflammatories is finished, your vet may want to take some radiographs (x-rays) of the stifle joint to confirm that the patella does indeed luxate and look at the position of the patella once luxated.

In addition to the standard views of the stifle, your vet should take a skyline or flexed skyline view of the stifle joint/patella. The vet will need to look at the end of the femur bone and see if the trochlear ridges are normal. These ridges help hold the patella in the proper position. In horses with a luxated patella (dislocated knee cap), one or both of these ridges will be malformed or missing. This will be important to know in order to determine if surgery is needed.

Once the radiographs are taken, your vet may refer your horse to a board certified equine surgeon for a consultation. In some cases, surgery will be required to correct the malformed femur and in other cases a more conservative approach may be available to help stabilize the patella and patellar ligaments. Once you have some more information about exactly what is going on, your vet will be able to give you a better idea of your horse’s future athletic prospects.

All the best!

— Dr. Chris Bell, member of the American Association of Equine Practitioners