Diagram of medial patellar luxation MPL in dogs

What to expect when your dog needs MPL (medial patellar luxation) surgery:

If your veterinarian has recommended MPL (Medial Patellar luxation) surgery for your dog, you probably have a few questions. This blog post addresses the top questions we get asked from dog owners about MPL surgery. We’ll walk through the most common questions and what happens before, during, and after your pet’s surgery.

What is an MPL?

Medial patellar luxation (MPL) is a condition also known as kneecap dislocation. It’s more common with smaller dogs but can be found in dogs of all sizes. Normally, the patella (kneecap) sits in a groove on the femur (thigh bone) and is secured by a tendon connecting the quadricep to the tibia (shin bone). When the knee is dislocated (patellar luxation), it rides outside of this groove when your dog’s knee is flexed.

Patellar luxation is one of the most common orthopedic conditions found in dogs, diagnosed in 7% of puppies, with breeds such as Boston and Yorkshire Terriers, Chihuahuas, Pomeranians, and Miniature Poodles being the most common. In nearly half of all cases, patellar luxation will be found in both knees.

What causes patellar luxation?

Most often, patellar luxation (kneecap dislocation) in dogs occurs for a variety of combined factors. It’s common to find the femoral groove (where the kneecap sits) is too shallow, causing the kneecap to dislocate more easily.

Rarely a patellar luxation can be caused by a traumatic injury, resulting in sudden and severe lameness, but this is much less common.

In cases where there is no trauma or breed-specific predisposition, it is thought to be caused by congenital or developmental misalignment of the limb.

Why do dogs need MPL Surgery?

Patellar luxation is evaluated by severity, ranging from a scale of 1-4, with grade 4 being the most severe.

Patellar Luxation Grades in dogs:

  1. The kneecap can be manipulated out of its groove but returns to its normal position spontaneously.
  2. The kneecap occasionally rides out of its groove and can be replaced in position through manipulation.
  3. The kneecap rides out of its groove most of the time but can be replaced in position through manipulation.
  4. The kneecap rides out of its groove all the time and cannot be manipulated back into place.

Surgery is typically recommended for dogs with low-grade luxation (1-2) that show frequent clinical signs or for dogs with a higher grade (3-4).

When surgical correction is performed early, the prognosis is very good, and most dogs go on to lead normal, active lives.

The condition typically does not respond well to medical management, especially in cases that have frequent clinical signs . Your surgeon and veterinarian can advise you as to the best course of treatment for your pet during an initial consultation.

Booking a consult with a surgeon:

At Animal Surgical & Orthopedic Center, we pride ourselves on having the highest number of board-certified surgeons available for consults in the greater Seattle area. Every consultation you book with us will be with the surgeon who will be performing your pet’s operation. You can book your first consultation with one of our surgeons today by calling (206) 545-4322.

How is patellar luxation diagnosed?

Primarily patellar luxation is diagnosed through palpation of the unstable kneecap during an orthopedic exam.

Symptoms vary significantly based on the severity of the dislocation, but frequently include:

  • Holding up of the affected leg
  • Lameness or limping
  • Shaking or extending the leg prior to use
  • Sudden carrying of the limb few steps (“skipping”)
  • Young puppies that may appear to be “bow legged”.

Additional tests may be used to diagnose conditions associated with patellar luxation. These most commonly include x-rays of the hind limbs to further evaluate for bony changes contributing to the patellar luxation.


Diagnosis of medial patellar luxation (MPL) before surgeryPalpitation of the affected limb

dog radiograph of medial patellar luxation (MPL) before surgeryRadiographs (X-rays) of patellar luxation

 (Images courtesy ACVS)

What happens during surgery for MPL?

During MPL surgery, your surgeon will first examine the joint for any and all changes associated with patellar luxation. Typically, the groove in which the kneecap (patella) rests will be deepened, to help the bone stay in place.

Diagram of knee joint in dogs for MPL surgeryThen, the tibial attachment of the patellar tendon (where the tendon attaches to the shin bone), may be adjusted to better align the patella with the groove where it rests, and will be secured with two small pins. This helps realign the knee joint to prevent the likelihood of future dislocations.

In some cases, an abnormally shaped femur causes the kneecap to luxate. In that case, the deformity will need to be corrected by cutting the bone, correcting the deformity, and stabilizing the bone with a plate.

The procedures that will be used to address the problem are selected on an individual basis by the veterinary surgeon. At ASOC, all our surgeons are board-certified and have extensive experience performing MPL surgeries.

Will my pet experience any pain during surgery?

At ASOC we use several different methods and modalities for pain management.

Anesthesia protocols commonly include the following:

  • Injectable narcotics/analgesics – Given before, during, and after surgery as needed to stay ahead of the pain. These are used either as intermittent injections or constant rate infusions.
  • Epidurals – Helps lower the doses required to maintain general anesthesia and can relieve discomfort for 8-12 hours after surgery.
  • Nocita- A long-acting (3 day) local anesthetic block administered during surgery.
  • Cold Compression Therapy – Provides post-operative control of swelling and pain with the use of cold and compression.
  • Post-operative oral pain medication combinations to be sent home for the first 1-2 weeks after surgery

 After surgery: Recovery timeline and outcome

Your surgeon will work with you to create a recovery plan specifically for your pet and your situation. Generally, the recovery period will take 8-12 weeks, and will include a plan to restrict the activity of your pet post-surgery. This includes minimal, if any, use of stairs, no off-leash activity, and no running, jumping, or playing with other dogs.

At ASOC, we typically perform two recheck appointments, the first being at two weeks after surgery and then another recheck at 6-8 weeks with potential recheck radiographs at this time. Afterwards, your surgeon will discuss with you if any other rechecks will be required.

You can find more information regarding post-op care on our website: https://www.animalsurgical.com/for-pet-owners/recovery-at-home/

 What is the success rate of MPL surgery?

Over 90% of owners are satisfied by the progress of their dog after surgery, and most dogs go on to live normal, active lives after surgery. This is especially true when surgery is performed early on after diagnosis.

The prognosis can be less favorable in larger dogs, especially when other abnormalities such as hip dysplasia are present.

What’s next?

At ASOC, our board-certified surgeons have helped thousands of dogs return to normal activities pain-free or largely pain-free. ASOC has always been a leader in adopting practices to improve outcomes and lower complication rates.

If you’re ready to book your appointment to consult with one of our surgeons about MPL surgery for your dog, give us a call at (206) 545-4322, or ask your veterinarian for a referral to Animal Surgical and Orthopedic Center.

We look forward to helping your pet live a happy, pain-free lifestyle!

Posted December 16, 2020 by Animal Surgical in Joint pain management, Pet Health, Uncategorized with No Comments

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