Luxating Patella

Updated on
June 4, 2022

A common injury when pet owners and veterinarians consider using a dog knee brace (stifle orthosis) is a Luxating Patella (AKA: dislocated knee cap, floating knee cap). The patella (knee cap) is held in place by a groove shape on the end of the femur (thigh bone) known as the “trochlear groove.” This groove allows the patella to glide up and down the end of the femur during stifle (knee) flexion and extension and prevent the quadriceps muscle tendon mechanism from sliding off the side surfaces of the femur.

A patellar luxation can occur due to malformation of the trochlear groove, curvature of the femur, or the shape of the patella. Trauma can also cause the patella to dislocate. The patella can luxate medially (inside surface) or laterally (outside surface). Patella luxation is common among smaller breeds but occurs in large breeds as well. Typically, a grading system is used to diagnose the severity of luxation; Grade 1 being less severe and Grade 4 being most severe. Your veterinarian is able to perform simple diagnostic tests to rule out or diagnose a luxating patella of your dog’s knee. Diagnostics may include radiographs, joint taps, among other manual manipulations of the knee joint (stifle) to “feel” the stability of the knee cap and determine a grade of luxation if present. Depending on the severity of your dog’s dislocated knee cap, an OrthoPets Stifle Orthosis (dog knee brace) may be a beneficial addition to your treatment plan.

In order to address a luxation of the patella, the tibia (shin bone) has to be positioned in a way to properly align the patella within the trochlear groove by aligning the quadriceps muscle tendon mechanism. This realignment of the greater tibial tuberosity (top part of the shin bone) improves the direction of pull of the quadriceps and patellar tendon across the trochlear groove. This is similar to the surgical outcome of the tibial tuberosity transposition (TTT). However, an OrthoPets dog knee brace can only be effective in realigning the quadriceps mechanism within Grade 1 and 2 presentations. Unfortunately, if your dog’s luxation has been diagnosed as a Grade 3-4 luxation, an external coaptation, such as an OrthoPets dog knee brace will not be able to achieve adequate tibial alignment nor would the patient tolerate the extreme twisting force needed to keep the knee cap in alignment. This is due in large part to femoral curvature deformity.

To learn more about our dog knee brace, take a look at our Stifle Orthosis page to view patients enjoying life with their dog knee brace. Talk to your veterinarian about an OrthoPets dog knee brace. OrthoPets has US Partner Clinics and worldwide Distributors to help you and your pet on your journey to restored comfort and mobility. We are here to support you and your dog’s knee injury or abnormal alignment!

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