WHAT’S A STIFLE?
The stifle joint is, of course, in the horse’s hind leg. It’s analogous to the human knee joint. However, the horse’s stifle is quite a bit different from the human knee. For example, the stifle “joint” is actually made up of three separate joints.
Horse’s have been observed to have problems with the stifle joint for a long, long time. Most commonly, this was seen as upward fixation of the patella (knee cap), where the horse’s leg would get stuck, that is, it couldn’t bend because the patella slipped out of its groove and was clamped in place by one of the three ligaments of the horse’s kneecap (this is another difference for horses – they have three patellar ligaments whereas humans just get one big patellar tendon). When the patella gets stuck in a horse, the horse, in another bit of the unique verbiage that has been around for hundreds of years, may be said to be “stifled.”
As we’ve learned more and more about horse joints, we’ve been able to get better images, so we have a much better idea what’s going on inside them. Sometimes, that means that we can even provide effective treatments. The stifle seems to have also become the subject of a lot more attention than in years past. Whereas previously, stifles never got much attention unless there was an obvious problem, now, at least in certain circles, there a lot of horses that get needles stuck into their stifle joints with somewhat alarming regularity.
STIFLE SURGERY
Under any circumstances, trying to figure out how to diagnose and treat many of the problems related to the equine stifle joints can be a frustrating challenge. It’s a big joint and it’s an important joint. Sometimes when something wrong can be found in one or more of the three joints that make up the equine stifle, surgery may be recommended, for example, for treatment of conditions such as osteochondrosis (OCD) or tears of the meniscus.
Which makes a recent study from the journal Veterinary Surgery so interesting. To answer the question, “How do they do after stifle surgery?” investigators at Colorado State University looked at 82 Western Performance horses – CLICK HERE to see an abstract of the study – and followed them up to see how they did. The study also tried to see if they could predict factors that would make it more likely than not that a horse would return to full performance after surgery.
Long Term Follow-Up
Results
Prognostic Factors
Still, even though the overall results weren’t that great, the investigators did find a number of factors that were associated with poorer outcomes. I think these are really important, if it comes to you trying to make a decision for your horse. Here they are:
- The degree of lameness was directly associated with outcome; the worse the lameness, the worse the chance that the horse would make a successful return to performance after surgery.
- Horses with more severe problems have less of a chance of returning to work than do horses with less severe problems (you might be able to see this on an X-rays, for example). This is usually the case in medicine, by the way.
- The duration of lameness was also an important prognostic factor; the longer the horse had been lame, the less the chance that he would return to his previous level of performance.
- Finally, if there were partial thickness lesions of the cartilage noted at the time of surgery, the chance that the horse would successfully return to work decreased.
Post-Operative Therapies
Here’s another part of the study that I think is important. I think it has some broader implications for treatment of all joints in all horses, as well.
Here is a list of the post-operative therapies used:
- intra-articular corticosteroids
- intra-articular interleukin‐1 receptor antagonist protein (IRAP)
- intra-articular hyaluronan/polysulfated glycosaminoglycans (Adequan®)
- Systemic nonsteroidal anti‐inflammatory drugs
- Systemic hyaluronic acid (Legend®)/polysulfated glycosaminoglycans (Adequan®)
- Oral joint supplements
Sound familiar? All of these treatments were given with good rationales: given with the best of intentions. All of them have some rather optimistic claims. However, exactly none of these commonly prescribed therapies made any difference in whether the studied horses returned to their previous level of performance.
CONCLUSIONS

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While the findings from this study aren’t particularly optimistic, I think that they are really important. From this, and other studies, one can reasonably conclude that the prognosis for full return to athletic function after stifle surgery is really quite guarded. Less than 40% of studied horses in two studies returned to their intended use following stifle surgery. Depending on risk factors, the chances that your horse will do well may be even less. In fact, make sure you understand what’s wrong with your horse and what the chances of a good outcome are before you decide to do ANY treatment for your horse.
Finally, for all of the therapeutic options that are available for post-operative care, given both directly into the joint, as well as systemically, none of them may be helpful in returning the horse to its previous level of use. In spite of what you may have read or been told, they aren’t going to prevent arthritis, either. I’d certainly never criticize anyone who would try to do everything that can be done for a horse, but while the rationale for the use of such therapies may be completely good, the reality is that current information would indicate that they are likely to be mostly a waste of time and money, at least after stifle surgery, and probably for a lot of other things. There is no reason to add financial insult to equine injury.
The death knell for an optimistic prognosis is often long-term follow-up. Hopefully, we learn.