Upward fixation of the patella, also known as locked stifle, is a condition seen in horses where the patella gets stuck in a locked position, leading to lameness. This condition is most commonly seen in younger horses as they grow. While surgery may be necessary in chronic cases, upward fixation of the patella can often be treated through conservative management techniques.
In this article, we will discuss the causes, symptoms, diagnosis, and non-surgical treatment options for managing upward fixation of the patella in horses.
Causes of Upward Fixation of the Patella
The root cause of upward fixation of the patella is imbalance between the vastus medialis muscle and the biceps femoris muscle. This leads to the patella getting pulled upwards and getting locked in that position. Some potential causes include:
Genetic predisposition in certain breeds like Thoroughbreds and Standardbreds
Conformational abnormalities like a straight or shallow trochlear groove
Limb abnormalities like valgus or varus deformities
Overwork and strain on the hindlimbs in young, growing horses
Symptoms of Upward Fixation of the Patella
The most obvious symptom is sudden onset hindlimb lameness, with an inability to fully extend the affected leg. Other signs include:
Stifle remaining in a semi-flexed or locked position
Resisted flexion and extension of the stifle joint
Pain and swelling around the stifle area
Shortened stride length in the affected hindlimb
Pointing of affected leg while at rest
Diagnosing Upward Fixation of the Patella
Veterinarians diagnose this condition through a combination of clinical signs, palpation of the stifle joint, and diagnostic imaging such as radiographs. Key things vets look for include joint effusion, thickening of the medial patellar ligaments, and abnormalities in the femoral trochlear ridges.
Conservative Treatment Options
Here are some non-surgical options vets may recommend for treating upward fixation of the patella:
Rest and reduced exercise to allow inflammation to resolve
Cold therapy such as ice packs to reduce pain and swelling
Anti-inflammatories and pain medication as prescribed by a vet
Slow-motion exercise program once acute inflammation is resolved
Patellar mobilization exercises to increase range of motion
Strengthening exercises to rebalance musculature around the stifle
Corrective trimming and shoeing to realign the leg
External coaptation splints to stabilize the limb
The prognosis with conservative management is generally good if treatment is started promptly. However, surgery may still be required if the condition becomes chronic or recurs frequently. Upward fixation of the patella can be frustrating for owners, but being aware of non-surgical treatment options offers hope for a full recovery. With proper rest and rehabilitation, most young horses return to full athletic function.