Understanding Canine Patella Luxation

If you're a dog owner, you've probably at least vaguely heard of patella luxation. But what actually is it, how do you know if your dog has it and why is it important to know?

Patella luxation is a widespread orthopaedic condition, particularly affecting small breed dogs. its characterised by displacement of the patella, causing pain, gait abnormalities and osteoarthritis. For us pet owners, diagnosing and managing this condition effectively is key to ensuring our furry friends stay happy and active. In this post, we will discuss all the 'what's' and 'why's' of the condition, including how to manage it!

What is Canine Patella Luxation?

As the name suggests, Patella luxation is the movement of the patella (the kneecap) out of its normal position (the trochlear groove). This usually occurs medially, or 'inwards' as appose to outwards. The abnormal movement is uncomfortable at the least, with pain and movement interference often depending on the severity, which is categorised via Grade's 1-4:

• Grade 1: The knee cap can be luxated with manual pressure, but is otherwise within the groove.

• Grade 2: The knee cap spontaneously luxates, which typically causes a sporadic skipping lameness

• Grade 3: The knee cap is permanently luxated but can be manually replaced in the groove.

• Grade 4: The knee cap is permanently luxated and cannot be manually replaced in the groove.

As the patella continuously moves in and out of the groove, it can wear away the local cartilage, causing the groove to become shallower, as well as kickstarting the development of osteoarthritis and pain. The displaced quadriceps muscles can cause internal rotation of the tibia overtime, thus placing stress on other hindlimb structures. Additionally, it is likely the dog will change their weight bearing and movement in attempt to avoid the discomfort, which expands the compensatory effects across the body; to include tense and contracted muscles and accelerated arthritis in other joints.

Illustration of a normal knee VS medial and lateral patella luxation (image owned by pethelpful.com)

Causes of Canine Patella Luxation

Several factors contribute to patella luxation, the most prevalent being genetic predisposition, related to the 'bow-legged' conformation. This abnormality displaces the powerful quadriceps muscles, causing deformation of the femur and tibia into a more pronounced 'bow' shape. As a result, the Trochlear groove (that houses the patella) also malforms, affecting its ability to hold the patella in place during movement.

Other developmental abnormalities such as hypermobility and hip dysplasia can also contribute to patella luxation, as well as traumatic injury. However, in my experience as a Veterinary Physiotherapist, the dog usually already has a degree of luxation, which is then worsened by the injury.

Clinical Signs and Symptoms

If your dog has patella luxation, you may observe several signs, such as:

• Sudden shifts in movement, like skipping or lifting a leg (and often holding it there)

• Running with both back legs together or 'bunny hopping'

• Reluctance to exercise

• Difficulty or avoidance to ascend stairs or jump

• Heat and/or swelling around the knee joint

• Protectiveness around the knee or hind end

• Excessive biting/grooming around the knee

• Audible clicking during movement

  
  

Spotting these signs early can facilitate timely treatment and help avoid complications.

Diagnosis of Patella Luxation

A canine Physical Therapist can aid the diagnosis (alongside your Veterinarian) through a comprehensive physical and gait exam. If your dog's quality of life is significantly impacted by the issue, diagnostic imaging like an X-ray or CT scan can be performed to assess the severity, as well as rule out any other musculoskeletal issues. If you're suspicious something is going on, it is recommended to keep a diary of your dogs behaviour to establish patterns, which may help save time with the diagnosis.

Management Strategies

Conservative Management

For grades I and 2, non-surgical management is often recommended, to include:

• Weight Management: Keeping your dog at a healthy weight allows more optimal limb function and can significantly reduce joint stress. Fat cells are also pro-inflammatory, which may exacerbate inflammation around the knee joint.

• Physical Therapy: Strengthening your dogs hindlimb muscle is vital to boosting joint stability, thus decelerating the rate of degeneration and arthritis. This can be achieved through targeted rehabilitation exercises and hydrotherapy. Your physical therapist can also work with you to combat any compensatory effects of the luxation, such as muscle tension and other gait abnormalities.

  
  

• Anti inflammatories/pain relief: Your Vet may recommend anti-inflammatory and pain relieving drugs to increase your dogs comfort. They can be especially useful initially alongside strengthening exercises. The same can be achieved through various Electrotherapies such as LLLT (Red light therapy) and PEMFT (magnetic field therapy), which many physical therapists use.

  
  

• Activity Modification: Even though we just said about strengthening the hindlimbs, this does NOT necessarily mean taking them for longer walks or running! Limiting high-impact activities can prevent the condition from worsening. Its all about quality over quantity.

  
  

A dog undergoing physical therapy (photo from WagWalking.com)

Surgical Intervention

For grades 3+ surgery might be necessary. Common procedures include:

• Tibial Tuberosity Advancement (TTA): This surgery repositions the tibial tuberosity to realign the quadriceps mechanism, so it no longer pulls the patella in an abnormal direction.

  
  

• Recession Sulcoplasty: This technique deepens the kneecap's groove, through removing a wedge or block of cartilage/bone, preventing the patella from sliding out of the groove.

  
  

• Femoral Varus Osteotomy: Utilised more for dogs with a severe bow of the femur (thigh bone), the FVO aims to straighten the femur, realigning the structures.

  
  

• Soft Tissue Stabilization: Often dogs have tissue surrounding the patella that are too tight or too loose, this technique aims to release tight tissues and tighten loose tissues to achieve better stability.

  
  

Post-surgery care generally requires limited activity for at least 6 weeks, physiotherapy and regular follow-up visits with the vet to ensure a smooth recovery.

The Importance of Regular Check-ups

Regular check-ups with a vet and physical therapist are vital for the early detection and management of patella luxation. They can offer advice on best practices to maintain joint health and lower the risk of the condition worsening.

Keeping them informed about changes in your dog’s movement or behaviour is crucial for tracking the progression of the condition over time.

Final Thoughts

Managing Patella luxation can be challenging at first but essential, often with fantastic outcomes. If you compete in sports like agility, don't panic! Many dogs with low grade luxation or whom have had surgical intervention can carry on their normal lives. The key is quick intervention and consistency in management.

Consider This

If you suspect your dog may be experiencing mobility issues or showing signs of patella luxation, reaching out to a Physical Therapist and Vet promptly is crucial. Proactivity always pays!