Joint decision

Despite the fact that in horses it sits much higher in the body, the stifle joint is the equine equivalent of the human knee, and its correct functioning is vital for maintaining soundness. It’s a complex joint involved in the transfer of huge weight-bearing forces, and its bones, ligaments, meniscuses and cartilage can be injured in a number of different ways, some of which are mild, others severe. Furthermore, the diagnosis and treatment of stifle issues isn’t always straightforward.

As in other joints, horses can suffer fractures, arthritis and a variety of different problems in their stifles, but some of these conditions are more common than others.

Complex construction

In a similar way to the human knee, the stifle is divided into three compartments and is formed by the femur, tibia and patella, whose articular surfaces are covered by smooth, slippery cartilage. There are several soft-tissue structures surrounding the joint, including two firm cartilage pads (meniscuses), which act as shock absorbers within the joint, two cruciate ligaments, which act in conjunction with two collateral ligaments to stabilise the joint, and three patella ligaments, which transfer the contraction forces created by the quadriceps muscle to the tibia, producing forward propulsion. Any of these structures can suffer injury or disease and a history of previous traumatic incident affecting them may or may not be relevant.

A range of symptoms

Stifle problems can show as poor exercise performance, and lameness can vary from mild to severe, from recent to long-standing and from intermittent to constant. Either or both hindlimbs may be affected and it may be possible to palpate fluid in one or more of the stifle joint compartments. In some cases, there will be generalised swelling around the area, but, in others, no abnormalities at all.

Did you know?

Specific gait abnormalities don’t automatically signify a problem with the stifle joint. This is also true of lameness following lifting, manipulation or flexion of the hindleg, although it can suggest further investigation is needed.

Top tip

Osteochondrosis is more common if young horses grow quickly, so managing nutrition to reduce the chance of rapid growth in yearlings may help reduce the risk.

Find out more about stifle conditions in July Horse&Rider – out now!