Patellar luxation is a common orthopedic condition in pets, especially small-breed dogs, which occurs when the kneecap (i.e., patella) moves out of its normal groove in the femur. Our Fusion Veterinary Orthopedics specialist Dr. David Dycus has years of experience dealing with patellar luxation, and our team provides the information you need to know about this condition.

Patellar luxation basics in pets

The patella is a small bone that sits inside the patellar tendon, which is located in a groove in the thigh bone (i.e., femur) and attaches below the knee onto the shin bone (i.e., tibia). Patellar luxation occurs when the kneecap slides or pops out of its normal position when the knee flexes, extends, and/or rotates. Patellar luxation can affect one or both hind limbs, and the dislocation can occur medially (inside) or laterally (outside). The condition is most common in small-breed dogs such as Chihuahuas, Pomeranians, miniature poodles, and Boston and Yorkshire terriers. However, this condition’s incidence has become more common in large-breed dogs and in breeds such as shar-peis, flat-coated retrievers, Akitas, and Great Pyrenees, who are considered predisposed to the disease. Cats are also susceptible to patellar luxation.

Patellar luxation causes in pets

Patellar luxation can result from trauma, causing sudden severe lameness in the affected limb, but the condition is most commonly diagnosed in pets who have not experienced traumatic injury. In these cases, the cause is unclear but likely attributable to several reasons such as genetics and skeletal abnormalities that affect the limb’s overall alignment such as:

  • Shallow femoral groove
  • Abnormal hip joint conformation
  • Femoral or tibial malformation 
  • Deviation of the tibial crest, which is the area where the patellar tendon attaches
  • Quadriceps muscle tightness or atrophy 
  • Abnormally long patellar ligament

Patellar luxation signs in pets

Patellar luxation signs vary depending on disease severity. Your veterinarian may detect this condition during your pet’s routine wellness exam, or if your four-legged friend becomes unable to bear weight on the affected leg. In most cases, affected pets suddenly carry the limb up (i.e., skip) for a few steps and may extend the limb before regaining normal use. As the condition progresses, lameness typically becomes more frequent. 

As the patella dislocates more often, surrounding cartilage erodes, leading to arthritis. In addition, other structures in the knee can become strained, potentially predisposing the affected pet to cranial cruciate ligament (CCL) rupture.

Patellar luxation diagnosis in pets

Dr. David Dycus can diagnose patellar luxation through a thorough orthopedic exam involving palpating the unstable kneecap. Additional tests he may recommend include:

  • Palpation under sedation to evaluate ligament damage
  • X-rays of the pelvis, femur, knee, and tibia to look for anatomical abnormalities
  • Computed tomography (CT) scan to provide a more detailed image of the hind limbs’ skeletal features

Patellar luxation treatment in pets

Conservative management may be sufficient for mild patellar luxation cases. This involves weight management, physical therapy, and medications to reduce an affected pet’s pain and inflammation. Surgery is often recommended for moderate to severe cases or when conservative management doesn’t alleviate signs. Potential surgical techniques include:

  • Reconstruction of the soft tissue structures surrounding the patella to help keep it in place.
  • Deepening the femoral groove to better accommodate the patella.
  • Repositioning the part of the tibia where the patellar tendon attaches to improve the alignment of the quadriceps, patella, and patellar tendon.
  • Correcting abnormally shaped femurs.

Patellar luxation surgery aftercare for pets

After surgery to correct patellar luxation, weight management is critical to help prevent undue joint stress. Pain management, involving medications, joint supplements, and alternative therapies, is also necessary to keep your pet as comfortable as possible as they recover. Additionally, postsurgical physical therapy, including controlled walking, hydrotherapy, and range-of-motion activities can help improve joint function and muscle strength.

If your pet is affected by patellar luxation, schedule an appointment with Dr. David Dycus of Fusion Veterinary Orthopedics so he can evaluate your pet’s condition and determine an appropriate treatment approach.