Hindlimb lameness can be a particularly frustrating challenge for many horse owners. Sometimes, it starts with a sense that something isn’t right, with a low-grade lameness that may be difficult to perceive under saddle. Many cases of lameness that are eventually attributed to the stifle often do present as lameness, but can also show up as poor performance, difficulty in transitions, uneven wear in the shoes, or stiffness.
The equine stifle is one of the biggest joints in the horse, equivalent to the human knee, and plays a vital role in propulsion and in stability, allowing the horse to sleep standing up. It is made up of:
- Two main joints: the femoropatellar joint and the femorotibial joint, with three compartments.
- Three patellar ligaments: cruciate ligaments and collateral ligaments also contribute to the stability of the joint.
- Two menisci: fibrocartilaginous pads that act as shock absorbers in the same way that they do in the human knee and unfortunately are just as prone to injury!
So, what kinds of problems do we typically see in the stifle?
Injuries often present during training and less commonly during competition. The common sites for injury are the menisci, or the ligaments. Both types of injuries are typically diagnosed using ultrasonography.
Ligament injuries may be treated with rest and controlled rehabilitation, in combination with anti-inflammatories and intra-articular medication. Stifle injuries may take a long time to resolve, with one recent study quoting that 59% of stifle injuries take longer than six months to resolve.
In the case of meniscal injuries, arthroscopic surgery is sometimes indicated to remove damaged tissue, but some cases may be managed with intra-articular medication and rehabilitation. It is worth remembering that in some injuries, rest and medication may be tried in the first instance, with surgery if the injury fails to resolve.
Osteoarthritis can affect the stifle, like many other joints. This is typically caused by wear and tear and may be exacerbated by poor conformation. This is often most easily visualised using radiography. The disease is progressive and incurable, but can be managed with anti-inflammatories, intra-articular medication, farriery and exercise.
In younger horses, we tend to see a developmental orthopaedic issue called osteochondrosis dissecans or OCD. This condition is most commonly found in large, fast growing horses where cartilage is weak or fragile and fractures into flaps or chips within the joint. This can be extremely painful and can develop on to osteoarthritis. The key to management of this condition is early diagnosis before too much damage can occur. Arthroscopic surgery is the mainstay of treatment of this condition.
Some owners may have experience of horses suffering from upward fixation of the patella. In this condition, the patellar ligament is tight, and the patella gets “locked”, leading to the hindleg being stuck in extension. This can be very distressing to witness. Walking the horse backwards often releases the patella, but this can occur frequently. Some cases will respond well to exercise, particularly hill work to build up the muscles in the hindlimb, but some will need surgery.
How do we work out where the problem is?
Clinical examination may give us a high index of suspicion that the lameness is in the stifle, however, to confirm our diagnosis, further diagnostics are usually necessary. Clinical examination may reveal swelling or pain in the joint. We often use local anaesthetic to confirm our suspicions. In some cases, we may need to block other structures in the leg first, to rule out other possible causes of the lameness. Once we have confirmed that the problem is associated with the stifle, further imaging is needed. For this joint, we use predominantly ultrasonography or radiography. Although MRI of the stifle can be performed, this is not common practice yet.
Regardless of the cause, early treatment and intervention is key, alongside a gradual, structured return to work. Hindlimb strengthening exercises such as pole or hill work can help to alleviate problems and to reduce the risk of injury. It is worth noting that many injuries occur during training, so care should always be taken to ensure that work is varied and not too repetitive. Always try to avoid excessive exercise on deep or uneven surfaces.
As previously mentioned, these cases may take a long time to respond, so patience is key. As with many other forms of lameness, a team approach with the vet, farrier, physiotherapist and trainer will help to ensure the best chance of success. As these cases can be very subtle in the early stages, it is excellent practice to get used to watching your horse trot up, so that any variations from the norm can be monitored.
If you have any concerns about your horse or would like one of our vets to check your horse, please call the practice where the team would be delighted to help.
