Have you noticed your dog skipping every once in a while or giving a little yelp of pain while walking? They may have a luxating patella. Read on to learn more about this condition and the surgery used to restore proper knee function.
Luxating Patella in Dogs
The patella is a small bone better known as a kneecap. It is located within the trochlear groove, under the patella ligament. The patella ligament attaches the thigh muscles to the shin bone (tibia).
As the thigh muscles expand and contract the patella ligament moves the bottom part of the leg. When operating correctly, the patella rides smoothly within the trochlear groove helping to keep the ligament in its correct position.
Luxation is another word for dislocation. Patellar luxation occurs when the patella pops or jumps out of the trochlear groove as the leg is flexed. So, a luxating patella could also be called a dislocating kneecap.
In dogs with patella luxation, surgery is typically recommended to relieve pain, and minimize cartilage wear, stress on other ligaments, and the development of arthritis.
Grades of Patella Luxation in Dogs
Patella luxation is diagnosed in grades which help to describe the severity of the dislocation.
Grade 1 - The patella pops out of the groove but quickly returns within a few steps or a couple of minutes.
Grade 2 - The patella leaves the groove and will return again, but after a longer period. Dogs will often carry, shake or extend the limb to help get the patella back into its proper location.
Grade 3 - Lameness becomes more frequent as the patella remains outside the groove for more frequent or extended periods. Cruciate ligament tears may result at this point due to poor leg alignment and knee rotation.
Grade 4 - Patella permanently luxated. Your dog may walk in a crouched position because they are unable to properly extend their knee. Pain will be persistent and knee damage will accelerate.
Symptoms of a Luxating Patella in Dogs
The severity of your dog's symptoms will depend upon the grade of their condition but may include one or more of the following:
- Hind leg weakness
- Intermittent skipping
- Hobbling
- Bunny hopping
- Refusal to jump
- Resistance to exercise
- Inability to run
- Leg appears bowed or knock-kneed
- Sudden yelp of pain when walking or running
- Difficulty rising up off of floor
- Swelling around the knee
Causes of Patella Luxation in Dogs
Patella luxation is typically an inherited condition but can also result from trauma to the leg. Cruciate ligament tears are a common cause of patella luxation. Although this condition can occur in dogs of any age, breed or size it is most common in toy and small breed dogs such as chihuahuas, French poodles, Maltese and Bichon Frise.
In about 50% of cases, both knees will be affected by the condition although it typically affects one side worse than the other. Whether your dog has a luxating patella in one knee or both it is likely to get progressively worse over time.
Treatment for Dogs with a Luxating Patella
Dogs experiencing grade 1 patella luxation can often tolerate the condition for many years without treatment. That said, arthritis is very likely to develop in later life leading to pain and reduced mobility. It is also important to note that even grade 1 patella luxation can lead to other knee injuries such as cranial cruciate ligament tears, which generally require surgery to correct.
Once the condition reaches grade 2 and beyond surgery will be required to prevent further damage, relieve pain, and restore proper knee function.
Surgery for Luxating Patella in Dogs
While techniques for patella luxation surgery in dogs will vary between veterinarians, the repair will typically involve the following steps:
- The attachment of the patellar ligament to the shin bone will be moved to its correct position.
- The trochlear groove where the patella should sit, is deepened to keep the patella on track.
- The joint capsule that holds the patella is tightened to prevent luxation from occurring.
- In some cases, an implant may be placed to contain the patella and prevent it from popping out of place.
What to Expect from Surgery for Luxating Patella in Dogs
To help your dog recover well from patella luxation surgery, you will need to follow your veterinarian's post-operative instructions carefully. Your vet will provide you with detailed instructions for at-home care and administering any required medications.
Weight-bearing is typically seen in dogs within the first week after surgery. By the second week post-surgery, most dogs can bear a moderate amount of weight on the affected limb. Twelve weeks after surgery all signs of lameness should have resolved.
Physical rehabilitation is often recommended to help the limb heal well and regain full mobility.
Prognosis for Dogs Undergoing Patella Luxation Surgery
Following surgery most dogs go on to live an excellent quality of life. Dogs undergoing surgery in the early grades of the condition typically regain excellent knee function and recover most of their strength and range of motion. Dogs experiencing grade 4 patellar luxation generally require physical rehabilitation to restore good mobility but tend to do very well after surgery.
If the surgery is performed after arthritis has developed, your dog may experience occasional discomfort, and the condition may continue to progress over time. However, the discomfort of arthritis can often be managed successfully, providing your pup with a good quality of life for many years.
It is important to be aware that while patella luxation can increase your dog's risk of cranial cruciate tears, this surgery does not guarantee that your dog is protected from them. These injuries can occur for various reasons including genetic factors.