By Dimitri Kadic MVM DES DACVS-LA DECVS
Photography: Courtesy Equitom

It is one of every horse owner’s worst nightmares. Your horse breaks a leg. Previously, that almost always meant end of story; the animal was best put out of its misery. But a lot of surgical progress has been made in recent years, so the perspective can now be quite different.

Bone fractures occur regularly in horses with often terrible consequences. Since most horse lovers are still convinced that a fracture in horses is fatal, we want to prove otherwise in this article. Anno 2023, we can repair a large proportion of fractures even in adult horses. The medical world continuously progresses, and even within equine surgery we have made a lot of progress in the last decade. Thanks to the development of new techniques and the innovation of materials for osteosynthesis (plates and screws, photo 1), we have been able to push our boundaries considerably.

Good healing possible

Bones are one of the most dynamic tissues in the body. They are richly perfused and, in addition to their supportive function (skeletal), have an important function in calcium and phosphorus metabolism. The numerous bone cells and blood vessels ensure that bone tissue is continuously created and broken down according to the forces acting on the bone. Moreover, bone is the only tissue that renews to a quality equal to the original tissue; bone regenerates, so to speak. At the other extreme are tendons, for example. These are much less well supplied with blood so the healing process is much more difficult and slower.
A condition for proper healing of a bone fracture is that the bone pieces are stable so that the fracture edges do not move too much in opposition to each other. Therefore, the surgeon’s main task is to bring the bone pieces together in the right place (reduce the fracture) and then fixate (stabilize) them in this position. This stabilization is usually done with screws and plates (photo 1), but in certain circumstances can be performed with wire (cerclage, photos 2a, 2b, and 2c) or pins (photos 3a and 3b, mandibula).
With proper reduction and stabilization of the fracture, the blood vessels of the two bone pieces will grow towards each other and carry cells that will initiate bone repair. Initially, the dead bone cells will be drained off, after which the production of new bone can stert. A bridge is created over the fracture line (callus), which will form the basis for bone repair. The better the reduction and stabilization, the smaller this callus, and the faster and better the recovery.

True fracture

There are a hundred-and-one different types of fractures, some of which are life-threatening and others relatively easy to fix. Some fractures are only partial and can be seen radiographically as a fine black line, which we also call a crack or fissure (photos 4a, 4b, 4c). If the bone fracture is more severe, the bone in question breaks completely and in this case is referred to as a true fracture (photo 5). If the fracture fragments no longer connect, we speak of a displaced fracture (photo 6).
In the horse, there are few or no muscles around the skeleton in certain places; think of the lower leg. In this place, the bone is only surrounded by tendons, blood vessels, nerves, and skin. Consequently, severe fractures in which the bone ends are displaced are not going to be protected by a solid muscle mass. These bone ends, which are usually sharp, are therefore going to quickly damage the surrounding nerves, blood vessels, and skin. If the skin tears, we speak of an open fracture, and environmental bacteria will infect the fracture site, possibly resulting in a bone infection (osteomyelitis). It is therefore very important to act quickly and correctly in case of a fracture... To read the complete article you need to be a subscriber
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