What is dog luxating patella?

Dog luxating patella, also known as patellar luxation, is a common orthopedic disorder characterized by the displacement of the patella (kneecap) from its correct anatomical position within the trochlear groove of the femur bone. This condition primarily affects small to medium-sized dog breeds but some larger breeds can also present with luxating patella.

The patella normally functions to support and stabilise the knee joint during movement, but in dogs with luxating patella, the patella moves out of its groove, resulting in varied degrees of joint instability. This displacement can occur on either the medial (inside) or lateral (outside) aspect of the joint, leading to different clinical presentations.

Why do dogs develop luxating patellas?

The exact cause of dog luxating patella is multifactorial, involving genetic predisposition, conformational abnormalities, and trauma. Congenital defects in the alignment and tracking of the patella can predispose certain breeds to this condition. Breeds such as Chihuahuas, Pomeranians, and Yorkshire Terriers are particularly prone to developing luxating patella.


Clinical signs of patella luxation in dogs?

Clinical signs of patella luxation in dogs range from exhibiting an occasional skipping or hopping gait, to intermittent lameness and hindlimb weakness, to more severe and persistent pain and joint dysfunction including a reluctance to use the affected limb and muscle atrophy due to reduced mobility and disuse.

The condition is graded based on its severity:

Grade 1: The patella is located in the trochlear grove but can be manually luxated. A spontaneous luxation during limb movement or limb manipulation rarely occurs. If the patella is manually luxated, it quickly returns to its anatomically correct position once the knee cap is released.

Grade 2: The patella is located in the trochlear grove but can spontaneously luxate with limb movement or limb manipultation. It can return to its anatomically correct position with knee extension or through manual repositioning.

Grade 3: The patella is located outside of the trochlear grove and can only return to its anatomically correct position with manual pressure.

Grade 4: The patella is located outside of the trochlear grove and cannot be returned to its anatomically correct postion.

The treatment for patellar luxation depends on the severity of the condition. Grade 1 and 2 luxations can be treated with conservative measures such as manual therapy, therapeutic exercise, weight loss, and medication. Grade 3 and 4 luxations usually require surgery to correct the alignment of the kneecap.


How we can help

One way to help manage patellar luxation (Grade 1 and 2) in dogs is to strengthen the quadriceps muscles, abductor and core muscles.

The quadriceps muscles are located on the front of the thigh and are responsible for extending the stifle joint, which is equivalent to the human knee. These muscles play a pivotal role in maintaining the proper alignment and tracking of the patella within the trochlear groove of the femur. When the quadriceps muscles contract, they pull the patella back into the groove which helps to prevent the patella from slipping out of place. In dogs with weak quadriceps muscles, the patella is more likely to dislocate, or slip out of place. When the quadriceps are strong and well-developed, they exert a more consistent and balanced pull on the patella, reducing the likelihood of patellar luxation. 

The abductor muscles are also very important in keeping the patella in the correct position by improving the biomechanical stability of the knee joint. The abductor muscles, particularly the tensor fasciae latae and gluteus medius, help to stabilize the femur and control its movement during various activities. When these muscles are strong and well-developed, they can exert better control over the positioning of the patella within the trochlear groove. Strong abductor muscles provide balanced forces around the knee joint. This balance helps prevent excessive movement of the patella, reducing the risk of it dislocating from the groove.

At Paws4Paws we teach you and your dog targeted strengthening exercises to help build muscle mass and improve patellar stability. Strengthening the quadriceps and abductors not only aids in patellar stability but also contributes to overall joint health and improved mobility in dogs.

In addition to strengthening the quadriceps muscles, core strength plays a pivotal role. The core muscles, which include the abdominal and lower back muscles, provide stability and support to the entire body. Dogs with patellar luxation often compensate for their knee instability by altering their gait and posture, which can lead to muscle imbalances and further joint problems. Building core strength helps address these compensatory mechanisms by providing a strong foundation for the entire musculoskeletal system. If necessary, we will address muscle imbalances by providing manual therapy such as remedial massage therapy, myofascial pain relief, trigger point therapy, passive range of motion exercises and stretching. 

In addition to strengthening the quadriceps, abductors and core muscles, it is important your dog maintains a healthy weight to avoid extra stress on the stifle.

We will also advise you on exercises that should be avoided and will make recommendations on potential home environment modifications.