What is it?
The patella (kneecap) normally sits within a groove at the end of the femur and moves smoothly as the stifle (knee) bends and extends.
In patella luxation, the kneecap slips either:
- Medially (towards the inside of the limb) — most common
- Laterally (towards the outside)
This displacement disrupts normal tracking of the joint, leading to:
- Abnormal loading of cartilage
- Soft tissue strain
- Joint inflammation
- Secondary osteoarthritis over time
It is commonly seen in small and toy breeds, but can also affect larger breeds.
Grading of Patella Luxation
Patella luxation is classified into four grades:
Grade I:
Patella can be manually displaced but returns to position spontaneously.
Grade II:
Patella intermittently luxates and may require manual replacement.
Grade III:
Patella is permanently luxated but can be manually repositioned.
Grade IV:
Patella is permanently luxated and cannot be repositioned.
Clinical severity does not always directly correlate with grade, which is why functional assessment is important.
Clinical signs & changes
Owners may notice:
- Intermittent skipping or hopping on one hind leg
- Sudden lifting of the leg for a few steps
- Reduced tolerance for exercise
- Difficulty jumping or climbing stairs
- Stifle instability
- Hindlimb muscle wastage
- Altered posture or weight shifting
Some dogs show only subtle signs, particularly in early grades.
Veterinary diagnosis
Diagnosis is made via:
- Orthopaedic examination
- Palpation and grading of patellar movement
- Radiographs to assess joint alignment and secondary changes
Management depends on severity and clinical signs:
- Conservative management (weight control, strengthening)
- Surgical correction in moderate to severe cases
- Pain management where osteoarthritis is present
Physiotherapy plays an important role both in conservative cases and following surgical correction.
Physiotherapy input
Rehabilitation focuses on improving stifle stability and correcting compensatory movement patterns.
A structured physiotherapy programme may include:
- Quadriceps strengthening to support patellar tracking
- Controlled sit-to-stand exercises
- Proprioceptive training and balance work
- Core stability exercises
- Gait re-education
- Pain management modalities where appropriate
Targeted strengthening improves dynamic joint stability and may reduce progression in mild cases.
Prognosis and long term management
Patella luxation can increase the risk of:
- Cranial cruciate ligament rupture
- Early osteoarthritis
- Chronic muscle imbalance
Long-term strategies include:
- Maintaining optimal body weight
- Regular controlled strengthening exercises
- Monitoring for progression
- Periodic reassessment
With appropriate management, many dogs live active, comfortable lives.