The patellar is the kneecap which is located at the front of the knee joint of the animal. Luxation is the medical term for dislocation. “Patellar luxation” is one of the most common knee-joint problems in canines. The displacement of the patellar from its normal position in the groove of the femur can occur both inwards and outwards.
This condition is predominant in dogs and more uncommon in cats. However, it may be more common in cats but undetected because cats do not show lameness in this condition. Small dog breeds such as toy poodles and miniature dog breeds are commonly known to be affected.
Clinical Signs and Observations
Signs depend on severity, degeneration, nature and occurrence of the disease. Persistent abnormal rear-leg carriage is evident in new-borns and puppies. Occasional skipping or rear-leg lameness worsens in young to mature dogs. In mature pets, sudden lameness may be seen due to minor trauma or worsening condition of joint disease. It can also be quite painful for the animal when the kneecap rubs an exposed bone, hence, animals would be less likely to apply weight on that leg and be more likely to let the limb hang while they walk.
Grades of Patellar Luxation
- Grade I – Kneecap can be displaced manually from its usual anatomical position, only to resume its position when pressure is released.
- Grade II – Kneecap can be moved out of place concurrently with bending of joint and resume when it is replaced manually or the joint is straightened.
- Grade III – Kneecap remains dislocated most of the time, but can be replaced manually when joint is straightened. Movement of the joint would also result in re-dislocation of the kneecap.
- Grade IV – Kneecap is dislocated permanently and cannot be replaced manually
- Grades III and IV – Animals often have a crouching, bow-legged or knock-kneed stance and most of their body weight would be transferred to their front limbs.
The animal’s activity level should be normal to restricted, depending on the severity of the condition. After surgery (if required), it would be good to encourage early and active use of the affected limb. Walks could be done on leash but take care to prevent jumping as it could hurt the surgery site. The weight of the animal also has to be monitored so as to decrease stress on the knee joint. Medications may also be prescribed to limit cartilage damage and degeneration while alleviating pain and inflammation.
Owners are encouraged to bring their pets for routine reviews so proper treatment for the condition can take place in time. As this condition can be genetic, these animals should also be discouraged from breeding. Breeding that previously resulted in affected animals should also be discouraged from repeat breeding.