A luxating patella occurs when the kneecap (patella) doesn’t track properly in the groove of the knee (stifle).
The kneecap sits in the tendon of the quadriceps muscle group which attaches to the bone just below the knee. When the quadriceps contract, they pull on the quadriceps tendon and kneecap. This results in straightening of the leg (knee extension).
If the kneecap is pulled out of its normal groove when the leg is straightened, it is called a luxating patella. In dogs this usually occurs on the inside of the knee joint.
Luxating Patella Incidence
A luxating patella is usually found in smaller dogs with the onset between 4-6 months of age. 7% of all puppies are affected and it can affect both legs in 50% of cases. It can be congenital, genetic and/or traumatic. In young puppies with severe luxating patella’s, the back legs often appear “bowed”.
Luxating Patella Symptoms
Initial symptoms may include limping, a skip in the gait, sudden loss of support of the leg, and/or abnormal sitting with the knee turned outward. The dog may kick their leg out to try and put the kneecap back in place. Once the kneecap is back in place the symptoms may disappear entirely. Symptoms can progress becoming more frequent.
Luxating Patella Diagnosis
Your Vet can diagnose a luxating patella through x rays and a physical exam. X rays will show the position of the bones of the knee (e.g. bowed), as well as the shape / depth of the groove. A physical exam will look for instability.
Cases are graded according to severity. Grade 1 is the least severe with the kneecap easily slipping back into place on its own. Grade 4 is the most severe with the kneecap stuck and fixed outside, usually medial, to its normal resting position in the groove of the knee joint.
Luxating Patella Treatment
In grade 3 or 4 luxations surgery may be the treatment of choice. Surgery may involve fixing the kneecap to the outside of the femur (thigh) bone to prevent it from sliding towards the inside. Alternatively, the groove of the knee may be deepened so that the kneecap doesn’t slip out of the groove.
Dogs with grade 1 or 2 luxating patella can live their entire life and never get arthritis or pain. It may have minimal impact on their life. Every situation is different. In these cases conservative treatments such as manual therapy and rehabilitation can be beneficial to ensure the muscles and joints of the rear legs are balanced and working optimally.
If the dog is not responding to the conservative treatment (the lameness is becoming more regular or its not resolving quickly), or there is diagnosed grade 3 or 4 luxating patella, further consultation with your Vet may result in a referral to a Veterinary Specialist to explore your options.
For further advice or consultation, please don’t hesitate to contact me to discuss how treatment can help.