In this article we look at a common joint condition in horses - equine 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 the best treatments for equine stifle injuries.
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.
Equine stifle injuries are a serious medical condition and require immediate treatment. In the majority of severe cases, prognosis for full recovery is limited. (c.4)
Equine Stifle: 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 (c.1) joint can be common, particularly with active horses.
Equine stifle injuries | How do horses damage their stifles
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.
Diagnosis of equine stifle injuries
An acute stifle injury in a horse will generally have swelling associated with it. The veterinarian will check for swelling and perform what is known as a 'flexion test'.
After observing the horse moving in hand or under the saddle, the vet will block the three joints if a stifle injury is suspected. All three joints are usually blocked at once to narrow down a lameness in that area.
If the horse is sound after blocking, the next step is using radiographs and ultrasound (c.2) to examine the stifle. These imaging technologies are typically used together, as certain areas of the stifle are better viewed with X-rays and others with ultrasound.
X-rays should reveal the presence of arthritis, bone cysts, or fractures. Ultrasound will show ligament or muscle injury
Stifle injury risks within horse disciplines
Stifle joint issues experienced by horses are a frequent source of rear limb lameness and will lead to diminished performance ad will require extensive periods of rest and recuperation.
Your horse is at higher risk to stifle injuries in western performance disciplines such as barrel racing and cutting, as well as in horses from other disciplines that rely heavily on hind-end engagement, such as reiners, cutters, 3-day eventing horses, dressage horses and show jumpers.
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.
Preventing Equine Stifle injuries
As many of our professional endorsed riders tell us, prevention is as important as cure. While it’s not always possible to prevent stifle injuries or lameness, there are effective ways to keep this essential joint in optimal condition.
(1) Ensure your horse has ample turnout time. Ideally, place them in a pasture with gentle slopes to encourage regular movement, which is beneficial for the stifles. For added benefit, pair your horse with other equines to promote more active movement.
(2) Incorporate strengthening exercises, either on the ground or under saddle. One effective exercise is to have someone hold your horse while you stand by its hip and gently pull on its tail. Continue pulling until the horse resists, engaging its back, abdominal, and quadriceps muscles. Hold for 10 seconds and then release, repeating the process 10 times per side.
(3) Regular hill work can help build the muscles that support the stifles and pelvis. Ensure the horse remains straight, keeping the haunches aligned while performing the work.
(4) Maintain your horse at a healthy weight to avoid excessive fat accumulation. Horses that are overweight and not properly conditioned are more prone to stifle injuries and lameness.
(5) Diet. As with all horses and looking to prevent all types of injuries - diet plays a crucial roll in the ongoing health of your horse and their stifles. A poor unbalanced diet can lead to significant issues.
(6) Provide equestrian tack developed to provide ongoing support to the horses joints and overall wellbeing; such as EQU StreamZ Horse Bands.
If your horse has a history of stifle injuries (or other equine joint issues) then in many cases an equine nutritionist can help you with personalised recommendations on how bets to care for the individual horse and ensure you are providing the adequate vitamins and minerals the horse requires.
Treatment for 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 NSAIDS (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 and can be used on horses with stifle injuries.
If the horse remains lame after several weeks of rest and recuperation then further investigation should be taken. 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.
Horses with mild stifle lameness may benefit from a period of rest, along with treatments such as non-steroidal anti-inflammatory drugs (NSAIDs) or injections containing corticosteroids and hyaluronic acid to reduce any inflammation. Your vet will provide guidance on when it will be possible to resume training, with an emphasis on gradually improving the horse’s conditioning.
We look at the most common treatments for horse with stifle injuries:
(1) Arthroscopy for stifle injuries
Arthroscopy (c.3) is a minimally invasive surgical option for horses that have no soft tissue abnormalities. It serves as both a diagnostic tool and a treatment method.
(2) Desmotomy for stifle injuries
While less common today, desmotomy involves cutting the medial patellar ligament and may be considered for horses that don’t respond to more conservative treatments.
(3) Corrective Shoeing on stifle injuries
In certain cases, corrective shoeing can resolve stifle locking issues. The farrier may trim the inner wall or apply a lateral heel wedge to assist with hoof rotation.
(4) Estrogen with stifle injuries
Injections of estradiol cypionate, a form of estrogen, are used to increase tension in the ligaments, particularly the distal patellar ligament.
(5) IRAP anti-inflammatory treatment on stifle injuries
This natural anti-inflammatory is derived from the horse’s own blood and injected into affected joints to reduce arthritis symptoms or other inflammatory conditions.
(6) Platelet-Rich Plasma (PRP) treatment for stifles
PRP therapy helps promote healing in soft tissue injuries by using blood from the horse, which is processed in a centrifuge to concentrate the platelets. The PRP is then injected into the injured area under ultrasound guidance. Since the horse’s own blood is used, there is no risk of allergic reactions.
(7) Stem Cell Treatments for stifles
Stem cells are extracted from the horse’s fat or bone marrow and injected into the affected joint. A study published in Veterinary Surgery in March 2014 assessed the effectiveness of this treatment. It found that 75% of horses with meniscal damage, treated with autologous bone marrow-derived mesenchymal stem cells (BMSCs) after arthroscopy, returned to their previous level of work. In contrast, only 63% of horses treated with arthroscopy alone showed similar recovery. The study concluded that BMSC treatment is safe and, in some cases, could allow horses to return to work without the need for arthroscopy.
(8) Laser Therapy & Hydrotherapy treatment on stifle injuries
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.
(9) Rest and Recuperation
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.
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 and of course providing a balanced diet.
Supplements used for equine 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. Nutritional supplements play a role in helping to support your horse’s joint function and mobility.
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.
Treatment for stifle injuries using Advanced Magnetic therapy
Over the years, advancements over traditional magnetic devices which predominantly use Neodymium magnets have become available to the equine community. Neodymium magnets have magnetic properties that claim to far exceed all other permanent magnet materials and are extremely low cost. An 8mm Neodymium 2000G magnets cost around £0.40, just as an example. As a result, they are the most widely-used magnets for industrial, technical, commercial and consumer applications including many horse boots, rugs, wraps and bands. Read between the lines when understanding the "strength" of the magnets used in devices; the majority of the time marketed in a way to simply bamboozle the reader. Traditional magnetism creates a thermal reaction in the body, ie. heat. Creating heat within an equine stifle injury can lead to further complications and create a delay to the healing process. Advanced Bio Resonance therapy creates a series of unique 360º magnetic fields - very different to Neodymium (or similar) magnets - which importantly for stifle injuries do not create a thermal reaction in the horses legs. This allows advanced magnetic therapy to be used alongside stifle injuries.
Equine stifle injuries | Summary
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.
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Cited Studies:
(c.1) Stifle lameness: Cohen JM, Richardson DW, McKnight AL, Ross MW, Boston RC. Long-term outcome in 44 horses with stifle lameness after arthroscopic exploration and debridement. Vet Surg. 2009 Jun;38(4):543-51. doi: 10.1111/j.1532-950X.2009.00524.x. PMID: 19538678.
(c.2) Ultrasound imaging of the musculoskeletal system including stifle injuries. Cook CR. Vet Clin North Am Small Anim Pract. 2016 May;46(3):355-71, v. doi: 10.1016/j.cvsm.2015.12.001. Epub 2016 Feb 2. PMID: 26847413.
(c.3) Frisbie DD, Barrett MF, McIlwraith CW, Ullmer J. Diagnostic stifle joint arthroscopy using a needle arthroscope in standing horses. Vet Surg. 2014 Jan;43(1):12-8. doi: 10.1111/j.1532-950X.2013.12068.x. Epub 2013 Oct 31. PMID: 24175893.
(c.4) Recovering from equine stifle lameness: Jeffcott LB, Kold SE. Stifle lameness in the horse: a survey of 86 referred cases. Equine Vet J. 1982 Jan;14(1):31-9. doi: 10.1111/j.2042-3306.1982.tb02331.x. PMID: 7084175.
