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Upward Fixation of the Patella


I have a 3 yr old gelding that started showing signs of stifle problems as a yearling, from a yearling to 2 yr old it progressively got worse and his legs, one or the other were locking up. I had his stifles injected a few times and the muscles above the stifle injected one time. As a 2 yr old I started giving him Equinyl Combo last October and started turning him out in pasture more, and he is now being ridden daily or exercised. His legs are doing good but I am not sure if it is the Equinyl Combo or he just grew out of it. One time when I ran out of the Equinyl Combo and gave him Grand Flex for 2 weeks he had a morning where his leg locked up when he walked out of the stall. Do you think I should keep him on the Equinyl Combo forever or try to get him off of it? It was hard to believe that the Equinyl Combo helped a loose ligament but I think that is what helped him. Thanks! – BW

Dear BW,
Just so that everyone’s clear, let me quickly explain what’s going on here, then move on to your question. It sounds like this horse has what is known as “upward fixation of the patella.” The patella is the small, bony plate (the kneecap) that protects the knee joint in people, where the femur and tibia meet. In horses, this joint is known as the stifle. A unique hooking of the patellar ligaments over a notch on the femur allows the horse to lock its hind legs in the standing position. Unfortunately, if one of these ligaments remains in the hooked position, the horse is unable to bend its hind legs. Of the three ligaments that support the patella, it is generally the medial, or inside, patellar ligament that is longer and weaker or “loose.” This problem can range from a slight delay in a leg’s forward motion to completely locking that freezes a leg for long periods of time and may be easier to see when a horse first moves off, is turned, or walks downhill.

Experts aren’t sure what causes this condition, but here are some things that have been suggested:

  • Poor muscle condition
  • Excessively straight hind limb conformation
  • Trauma to the stifle
  • Debilitation (undernourishment or ill health)

Upward fixation of the patella is more common in young horses and ponies, and is also seen when a horse is taken abruptly out of training and confined to a stall, losing weight and muscle condition.

Now to your question: did he grow out of it or did the Equinyl Combo help? Personally, I think a combination of things have improved your horse’s condition. First, he is getting older, and as he gains height and weight the problem may be self-correcting. Two, you added a supplement with ingredients to help manage pain and inflammation which have been associated with this condition. Third, and this may be the most important thing, you have begun exercising him daily and providing more pasture turnout. There are some things that may lead to upward fixation of the patella that you can’t change (like conformation), but there are other things that you can change (like muscle tone), and it sounds like you’re doing a great job with that.

I encourage you to continue the exercise and turnout, explore corrective trimming and shoeing with your farrier, and keep him in the best overall health possible by working with your veterinarian to develop a good vaccination, deworming and dental care schedule. Feed him to be at an ideal body condition score (5 on a scale of 1 to 9). And if you feel that the Equinyl Combo is helping, by all means continue it. I don’t believe it’s doing any harm and might encourage him to keep moving through some mild stiffness and soreness.

Lydia F. Gray, DVM, MA SmartPak Staff Veterinarian and Medical Director Dr. Lydia Gray has earned a Bachelor of Science in agriculture, a Doctor of Veterinary Medicine (DVM), and a Master of Arts focusing on interpersonal and organizational communication. After “retiring” from private practice, she put her experience and education to work as the American Association of Equine Practitioner’s first-ever Director of Owner Education. Dr. Gray continues to provide health and nutrition information to horse owners through her position at SmartPak, through publication in more than a dozen general and trade publications, and through presentations around the country. She is the very proud owner of a Trakehner named Newman that she actively competes with in dressage and combined driving. In addition to memberships in the USDF and USEF, Dr. Gray is also a member of the Illinois Dressage and Combined Training Association (IDCTA). She is a USDF “L” Program Graduate and is currently working on her Bronze Medal. Find Dr. Gray on Google+

Posted in Ask the Vet, Lameness

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4 comments on “Upward Fixation of the Patella
  1. lisa given says:

    my horse has a fractured stifle . I was told that joint supplements or any supplements for joints Id bespending extreme amount of money and would not work. I would like to know if that’s your take. we did try the steroid route but it did not work. Thankyou

    • SmartPak SmartPak says:

      Hi Lisa, I’m sorry to hear about your horse’s injury. In terms of whether a joint supplement will “work,” we would have to keep in perspective what the goal of supplementing would be. For example, if your horse seems to experience discomfort associated with the stifle, it’s possible that a supplement with ingredients to support joint health and a normal response to inflammation may help in keeping him comfortable. It may be a case where you simply try something with your horse and note if it seems to make any difference in his comfort or way of going. – Dr. Lydia Gray

  2. Kiley Patrikus (me) says:

    Hi! my horse has upward fixation of the patella and I’m wondering if theres any supplements that will help it get better?

    • SmartPak SmartPak says:

      Thanks for your question, Kiley. We’re sorry to hear about what has been going on with your horse! Unfortunately, there is no supplement that will help a specific condition like this to get better, although there may be role for certain ingredients like MSM and omega 3s (which help support a normal response inflammation) and Devil’s Claw and yucca (which may help manage discomfort). We’d suggest checking in with your veterinarian for the best course of action in this case and to see if and how supplements may fit into your horse’s individual program. – Dr. Lydia Gray

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