In this article we look at a common joint condition in horses - stifle injuries. We investigate what stifles in horses are, what injuries horses can get with their stifles, the meaning of the term ‘locked stifle’ and try to understand what stifle lameness is and how best to treat the condition.
Where is a horses stifle?
A horses stifle is a joint found in the horses hind legs which could be compared to a humans knee. The purpose of the stifle joint is to provide flexion and extension of the back legs - just as our knees do for us.
Stifle joints are in fact the largest joints in a horses body and on first appearance do not look like joints as they are hidden within the structure of the horses back legs. A horses stifle is positioned where the horses femur bone meets the tibia bone.
A stifle is an extremely complex joint. Surrounding the horses stifle is a complicated structure of muscles, two collateral ligaments and soft tissues. Inside the stifle joint itself is also complex, containing two joint cavities which are supported by two cruciate ligaments. There are also three patellar ligaments and the joint capsule itself which provide lubrication to the joint. In total there are fourteen ligaments which support the joint.
What is the function of a horses stifle?
A horses stifle joint is used to propel them forward, whether leaping over a jump or running through a field. When your horse strides forward the stifle joint pulls your horses hind legs forward and is thus vital in enabling the horse to move.
The stifle joint itself is encircled by a thin capsule which also provides a level of shock absorption and lubricates the joint.
Along with providing movement, a horse stifle is also uses to support the horse when standing - often referred to as their ‘stay apparatus’. One key difference of a horses stifle compared to a humans knee is that when a human stands still our knees and legs are positioned vertically straight to the ground whereas a horses stifle joint is actually angled when the horse is standing still. A horses stifle will lock into place allowing the horse to rest whilst standing up.
With such an intricate structure it should be no surprise that injuries and lameness to a horses stifle joint can be common, particularly with active horses.
Stifle injuries in horses
The vast majority of stifle injuries experienced by horses are found due to a result of repetitive stress on the joint or following a traumatic injury often associated with quick changes in direction or rapid deceleration. In less common cases a horse can develop a stifle injury through developmental issues.
Repetitive stress on the horses stifle, as with many joints, is prone to equine arthritis in the joint itself and can often be as a direct result of an injury. Osteoarthritis of the stifle joint is a progressive condition which can develop over a period of time and is more commonly seen in older horses.
The stifle joint can also be subjected to an injury following a fracture or dislocation of the joint.
As the stifle is a high-motion joint injuries are commonly associated to high-speed movement, jumping and whilst the horse is turning at high speeds. Because of this, sports horses such as animals competing in showjumping, 3-day eventing or barrel racing are common - however, reality is that any horse of any age can experience stifle injuries.
Symptoms of stifle injuries
If your horse is showing symptoms of a stifle injury they are likely to show lameness in their hind end and indicate one or more of the following symptoms:
- Swelling and inflammation around the stifle area
- Dragging of their toes
- Unable to canter
- Inability to back up or walk backwards
- A reduced stride length
- Issues going up or down hills
Developmental issues surrounding stifles will be caused by a deformity and are normally present from birth, often resulting in swelling and inflammation of the stifles from an early age. In many cases developmental issues will be intermittent and will often be more visible in exercise and reduced when activity is reduced. Examples of these developmental disorders can include subchondral bone cysts, patterer laxation or osteochondritis dissecans.
Locking stifle in horses
A commonly discussed symptom of a horses stifle is “locked stifle”. This condition is, as the name suggests, when the stifle becomes locked into position and unable to move out of the ridge on the end of the horses femur. This results in the horse not being able to bend their leg resulting in the leg remaining extended and the horse dragging their toe. It’s clinical name is Upward Fixation of the Patella (UFP).
Locking stifles is not fully understood but is thought to be caused by conformation issues in some horses and can also be found in younger horses who grow quickly or have poor body condition, preventing the medial ligament to operate properly and resulting in locked stifles.
A horse with locked stifles is immediately obvious and although the condition can be alarming it rarely creates pain. It will however create an element of lameness. The horse will likely begin to take shorter strides and in some cases a small clicking sound can be heard, often called ‘clicking stifles’.
If you suspect your horse has locked stifles they will require an immediate inspection by your vet. Diagnosing the exact cause will normally be done by using X-rays to rule out other issues relating to the stifle such as fractures, foot abscesses or stringhalt.
Treatment of locked stifles vary. In many cases a specific exercise program can release the issue alongside use of supplements, but if your horse is not reacting to this treatment then surgery may be required - which is a risky operation called Medial Patella Desmotomy where the horse is traditionally sedated.
Using local anaesthetic can help reduce the risk to your horse. Your vet will be best placed to provide the correct treatment for your horse and in many cases corrective shoeing with your farrier can aid recovery from a locked stifle. Many owners are now adopting hydrotherapy treatment to support a horses recovery from locked stifles.
Treating stifle injuries in horses
Following a thorough investigation by your vet, a treatment plan will be developed based on the specific case. As with many conditions the most pressing treatment is rest. Allowing your horse to rest will help to alleviate any swelling and provide the stifle joint with an opportunity to heal. With a majority of stifle injuries box rest of between 2-3 months will be recommended.
Providing the horse with anti inflammatory medication is sometimes possible, but if not many now look at advanced magnetic technology to aid a reduction in inflammation, naturally. EQU StreamZ magnetic horse bands and are well respected in the industry, supported by having the highest rating of any magnetic horse bands on the market.
If the horse remains lame after several weeks of rest and recuperation then further investigation will be required. If a lesion is present and shown in an x-ray surgery may also be considered, particularly if the horse has damage to their collateral ligament or cruciate ligaments.
In some cases stifle injections can be administered. Although commonly used, injections can carry with them risks so it is vital these are discussed with the vet. Injections in the joint can last for several weeks but in some cases can be effective for 6-12 months and can cost anything from £50 - £100.
Whatever the treatment, rest is of paramount importance. Tissue healing within the stifle can take up to a year to heal properly. Once treatment has begun and is underway then many will look to introduce a controlled exercise program aimed and developing physical therapy into their daily routine.
Laser therapy is now widely used as a complementary procedure as well as hydrotherapy. Hydrotherapy is particularly useful as it allows the horse to develop muscle and joint movement whilst supporting the load on the stifle.
Once your horse has recovered from a stifle injury then continuous monitoring of the condition is important, along with adoption of physical therapy techniques which can support their long term soundness.
Supplements for horses stifle injuries
You can help boost your horses chances of preventing a stifle injury, or reacting to an existing injury by managing their supplement intake.
There are a variety of supplements available within the equine community specifically marketed as joint supplements. Many of these supplements contain glucosamine (aimed at repairing the cartilage), MSM (used to support a reduction in pain and/or inflammation), Chondroitin (to help prevent further destruction of the cartilage) and hyaluronic acid (used to help lubricate the joint). Omega-3 is also widely used within equine joint supplements alongside various alternative therapies.
A horse who has developed a stifle injury can be a worrying sight for many owners. Ultimately there are many reasons why your horse may have injured their stifle and in all cases you should stop riding the horse until you fully understand their condition.
Understanding the cause of the issue is important and with the correct approach the prognosis is good - rest and recuperation will be required.
Advancements with imaging techniques developed to diagnose conditions now help professionals accurately establish what the exact cause of the injury is and provide a targeted program for recovery. Seek medical advice which will begin with a visual exam and will likely be supported with imaging techniques such as x-ray radiographs and thermal imaging.
Treating your horse will heavily depend on the exact injury and only a small volume of cases will involve invasive surgery.
As stifle injuries are so common, particularly in active horses, try to avoid stifle injuries by not overworking your horse, providing them with a healthy diet, administer supplements to support their joints and even look at tack to support their ongoing joint health.