Luxating Patella in Cats: Causes, Symptoms & Treatment

Understanding Luxating Patella in Cats

Luxating patella, also known as patellar luxation, is a condition in which a cat’s kneecap (patella) slips out of the groove in the thigh bone (femur) where it normally sits. This displacement can cause discomfort, lameness, and reduced mobility in affected cats. While this condition can develop gradually as a kitten grows, it may also result from physical trauma to the knee joint, including injuries to the bones, patellar ligaments, and tendons.

The condition is relatively uncommon in cats compared to dogs, but when it occurs, understanding its severity and treatment options is essential for maintaining your feline companion’s quality of life. The underlying cause typically involves anatomical abnormalities such as a shallow trochlear groove (the channel where the kneecap sits), bowleggedness, cow-hocking (excessive outward curvature of the leg bones), or an off-center attachment point on the tibia.

Grading System for Patellar Luxation

Veterinarians use a standardized grading system to classify the severity of luxating patella, which helps determine the appropriate treatment approach and prognosis. Understanding these grades is crucial for cat owners to comprehend their pet’s condition:

Grade I Patellar Luxation

Grade I represents the mildest form of patellar luxation. In this grade, the patella can only be luxated (moved out of place) when external pressure is applied to it. Once the pressure is released, the kneecap returns to its normal position in the femoral groove spontaneously. Cats with Grade I luxation typically experience minimal to no clinical symptoms because their kneecap remains properly positioned most of the time.

Grade II Patellar Luxation

Grade II luxation is characterized by intermittent spontaneous displacement of the patella. Unlike Grade I, the kneecap occasionally pops out of place on its own but generally remains in its normal position. The patella will stay out of place until the leg is hyperextended and rotated, at which point it returns to the groove. Cats with Grade II luxation typically exhibit intermittent limping or an occasional reluctance to bear weight on the affected leg.

Grade III and IV Patellar Luxation

Grades III and IV represent the most severe forms of patellar luxation. In Grade III, the patella is permanently luxated but can still be manually moved back into place. Grade IV is the most severe, as the kneecap is permanently out of place and cannot be repositioned back into the groove. Cats with these advanced grades experience persistent lameness, may refuse to use the affected leg, and often develop signs of arthritis such as joint swelling and pain.

Clinical Signs and Symptoms

The symptoms of luxating patella in cats vary significantly depending on the severity of the condition. Early recognition of these signs is important for timely intervention:

Common Symptoms Include

• Limping or skipping on the affected leg
• Intermittent or persistent lameness depending on grade
• Reluctance or inability to bear weight on the affected limb
• Difficulty or inability to run or jump normally
• Reduced time spent in favorite high places
• Decreased grooming activity resulting in poor coat condition
• Signs of pain when specific areas are touched
• Swelling or abnormal enlargement of the knee joint
• Visible knobby or enlarged appearance of the knee

It’s important to note that cats with Grades III and IV may learn to compensate for their condition, sometimes even teaching themselves how to pop the patella back into place. However, they will typically avoid using the affected leg and may show obvious signs of discomfort.

Treatment Options for Luxating Patella

Treatment approaches for luxating patella vary considerably based on the severity of the condition, the cat’s overall health, and the progression of symptoms. A comprehensive treatment plan should address pain management, mobility, and prevention of further complications.

Conservative Management

For mild cases, particularly Grade I and some Grade II luxations that don’t cause significant lameness, conservative management may be sufficient:

• Exercise restriction to minimize stress on the affected knee
• Physical therapy and rehabilitation exercises
• Prescription anti-inflammatory medications
• Pain relief medications as needed
• Weight management in overweight cats
• Joint supplements to support cartilage health

Many cats with low-grade luxations can be managed effectively with supportive care without requiring surgical intervention. However, regular veterinary monitoring is essential to ensure the condition doesn’t progress.

Surgical Correction

Surgery is typically recommended for cats with Grade III and IV patellar luxation, or for Grade II cats with persistent lameness that doesn’t improve with conservative management. The goal of surgery is to permanently restore the patella to its proper position in the femoral groove and adjust the tension of surrounding tissues to maintain correct positioning.

Surgical Techniques

Several surgical techniques may be employed, often in combination, to address luxating patella:

Trochleoplasty

This procedure involves deepening the trochlear groove to provide a more secure channel for the patella. By creating a deeper groove, the kneecap is less likely to slip out of place during normal movement and activity.

Tibial Crest Transposition

When the attachment point on the tibia (shin bone) is off-center, surgeons may reposition the tibial crest to center it properly. This realignment helps maintain proper patellar tracking and reduces luxation.

Soft Tissue Adjustment

Surgeons may alter the inappropriate tension on the patella by releasing or cutting tight connective tissue that is pulling the kneecap out of place. They also tighten stretched tissues that should be holding the patella in the correct position through a process called imbrication. This typically involves overlapping fascial edges with specialized suture patterns to remove excess laxity from the soft tissues surrounding the patella.

Implant Placement

In some cases, an implant may be placed on the inside of the knee to prevent the patella from slipping over the edge of the femoral groove.

Surgical Success Rates and Prognosis

The success of surgical treatment for luxating patella depends significantly on the grade of luxation:

• Grades I, II, and III: Surgery is usually very successful, with little to minimal chance of recurrence
• Grade IV: Approximately 50 percent chance of recurrence despite surgical intervention

For most cats with patellar luxation, veterinarians recommend surgery sooner rather than later to minimize the likelihood that arthritis will develop in the affected joint. The longer the condition persists, the greater the risk of degenerative changes to the knee cartilage.

Post-Operative Recovery and Care

Following surgical correction of luxating patella, appropriate post-operative care is essential for optimal recovery and long-term outcomes.

Immediate Post-Operative Period

Patients are typically kept in the hospital overnight and discharged the day following surgery. Recovery is usually rapid, especially with appropriate pain management strategies. Post-operative activity must be strictly limited during the healing phase.

Recovery Protocol

The typical post-operative care plan includes:

• Strict crate rest for approximately 8 weeks following surgery
• Prescription anti-inflammatory medications
• Pain relief medications as prescribed by your veterinarian
• Hot and cold compress therapy
• Maintenance of a calm, relaxed environment
• Minimal and carefully controlled physical activity
• Physical therapy and rehabilitation exercises
• Postsurgical recheck examinations at 2, 6, and 12 weeks

Long-Term Management

Following the initial recovery period, long-term management strategies may help maintain joint health and prevent complications:

• Joint supplements containing glucosamine and chondroitin
• Prescription anti-inflammatory medications
• Antibody therapy such as Solensia® to manage pain and inflammation
• Therapeutic mobility diets designed to support joint health
• Weight management programs for overweight cats
• Ongoing physical therapy and rehabilitation as recommended

When to Seek Veterinary Care

If your cat exhibits any signs of joint pain or mobility issues, prompt veterinary evaluation is essential. Attempting to diagnose or treat these symptoms at home before seeking professional veterinary care is not advisable, as many health conditions can cause similar symptoms. Some conditions are more serious than others, and only a veterinarian can determine the underlying cause through physical examination and diagnostic imaging.

Delaying veterinary care can allow conditions to progress, potentially causing more severe and permanent damage. Early intervention typically leads to better outcomes and faster recovery.

Frequently Asked Questions

Q: Can a cat’s luxating patella heal on its own?

A: Low-grade patellar luxations in cats may be managed with supportive care such as medication, physical therapy, and activity restriction, but they may not resolve completely without intervention. Severe luxating patellas require surgical treatment to keep the patella in its proper position and prevent complications such as arthritis development.

Q: What is the best treatment for a luxating patella in cats?

A: The best treatment depends on individual factors including the cat’s age, overall health, and the severity of the condition. Minor cases sometimes respond well to conservative management with physical therapy, medication, and controlled activity. For severe luxations, surgical treatment is typically warranted to prevent chronic lameness and permanent disability.

Q: How long is the recovery period after luxating patella surgery?

A: The typical recovery period involves 8 weeks of strict crate rest, with regular recheck examinations at 2, 6, and 12 weeks post-surgery. However, complete recovery and return to normal activity may take several months depending on the individual cat’s healing process.

Q: Will my cat need surgery if diagnosed with luxating patella?

A: Not necessarily. Mild Grade I luxations may not require surgery, and some Grade II cases can be managed conservatively. However, for Grade III and IV luxations or cases with persistent lameness, surgery is generally recommended sooner rather than later to prevent arthritis development.

Q: What causes luxating patella in cats?

A: Luxating patella typically develops due to anatomical abnormalities such as a shallow trochlear groove, bowleggedness, cow-hocking, or an off-center tibial attachment point. It can also result from physical trauma to the knee joint or surrounding structures.