Kneecap (MPL) Surgery in Dogs

Repairing Dislocated Kneecaps Through MPL Surgery

Knee surgery in dogs is more common than you think – especially as a wide variety of breeds suffer from a condition nicknamed ‘trick knee’.

While many pet parents have heard of cruciate ligament injuries afflicting their furry companions, few know about medial patella luxation (MPL), which is simply the medical term for a dislocated kneecap.
The patella/kneecap can slip out of its normal groove and this often results in lameness, inflammation, and discomfort for your pooch. In these dislocation cases, the kneecap has slipped out of the smooth groove in which it normally rides up and down. It has slipped medially – towards the opposite leg – as opposed to laterally, which would be away from the dog entirely. The knee cannot extend properly and stays bent. With luck, the kneecap can be slipped back where it belongs and things can return to normal in only a few steps. But for some dogs, normal extension of the rear leg is a mere dream only achievable with surgical correction.

Some tell-tale signs that your dog has suffered a dislocated kneecap are: a little skip in its step, stiffness of a hind limb, or the dog may even run on three legs, holding one hind leg up, and then be back on four legs as if nothing has happened.

Failure to treat the condition can lead to progressive debilitating arthritis of the joint. But don’t stress, these knee problems in dogs can often be corrected with the right intervention.
In this article, we’re going to cover:

• Which type of breeds are most prone to these particular knee problems in dogs.
• Why some cases give less cause for concern, while others require surgery.
• The four different grades of this condition and when Kneecap (MPL) surgery is necessary.
• The various surgical options that are available.
• Top tips for post-operative care to ensure your dog heals properly.

Which Dog Breeds Are Affected?

This health issue has a higher incidence rate among the following dogs: Affenpinscher, Brussels Griffon, Chihuahua, Poodle, Pug, Shih Tzu, English Toy Spaniel, Japanese Spaniel, Greyhound, Maltese, Miniature Pinscher, Papillon, Pekingese, Pomeranian, Manchester Terrier, Silky Terrier, and Yorkshire Terrier.

In around half of these cases both kneecaps of the dogs are affected, while the other half usually only suffer with one.

The Different Grades Of This Knee Problem

Veterinary surgeons assess the severity of medial patellar luxations and categorize them as follows:

Grade 1
This is when the kneecap can be moved out of place manually but will fall back into its natural position once let go of. No surgery needed.

Grade 2
At this next stage the kneecap occasionally slips out of its groove, creating an intermittent lameness. The kneecap goes back into place on its own, but occasionally surgery is required. This depends on how often lameness is a problem, and how long this lameness lasts.
If the ridge of bone on the inside of the knee wears down, the situation can deteriorate. Therefore, proceeding with surgery can prevent a decline to the next stage.

Grade 3
At this point the patella is out of place all the time but can be carefully manipulated back into its normal position. However, it will not stay there and the dog may seem to crouch or slant downwards in the rear.
Weakness or lameness at the rear may persist. The dog may also have a bow-legged appearance due to the ongoing dislocation. Surgery is definitely required at this stage.

Grade 4
The most serious stage when the patella is out of place permanently – and no amount of manipulation can return it to correct positioning. Extension of the knees will be very difficult for the dog, meaning it will be walking with knees bent virtually all the time.
Having the kneecap out of place for prolonged periods can have a very negative impact, with the weight-bearing stress on the rear legs causing changes in the hips, long bones, and ultimately arthritis.

The overall health impact depends on how severe the dislocation is and how long this has been occurring. Surgical correction with Kneecap (MPL) Surgery and total resolution of the lameness may not be possible, but our experts at SurgiPet can discuss the situation in detail with you.

Knee Surgery For Dogs: What Surgical Procedures Are Available?

First Option: Lateral Imbrication
This procedure alone may be adequate for a mild case but is often used as a procedure to supplement one of the other surgeries.
Surgery around the joint capsule will prevent the slipping of the kneecap, meaning it is confined to its proper groove.

Second Option: Trochlear Modification
The patella rides in a groove at the bottom of the thigh bone, however In toy breed dogs this groove is shallow – which allows the patella to slip.
Surgery involves removing some cartilage and forming a deeper groove in the bone underneath so that the patella stays where it belongs. The cartilage is also replaced.

Third Option: Tibial Crest Transposition
This is a necessary procedure in cases where the tibias (leg bones) have rotated. In particular, the crest on the tibia where the quadriceps femoris (thigh bones) attaches may have migrated inward.
Surgery involves removing the crest and pinning it back where it belongs to straighten out the leg. Severe rotation of the tibias may involve cutting through the entire bone and de-rotating back into position.

Fourth Option: An Implant
In this surgical option a small, curved plate is implanted to add height to the ridge of bone on the inside of the knee. By making this area larger, the kneecap cannot slip over it.
This procedure can be used as a sole solution for Grade 2 dislocations or as an adjunct to the other surgical options.

Every case needs to be assessed individually. Here at SurgiPet, we’re happy to give advice and discuss the best options with you during consultation.

Following MPL Surgery: Ensuring Your Dog Heals Properly

Post-surgery, prescribed medications should be given to make sure that your pet’s pain is well-controlled and infection is prevented. Exercise must be restricted.

It’ll take about two weeks before your dog can begin walking gingerly on the operated leg, and in some cases may have to be retrained to use the leg after surgery.
Therefore, expect some confinement to a large crate or dog pen, and the support of a sling during their recovery.

A period of 2-3 months will have to pass before your dog will be using the leg well. We recommend two months of strict activity restriction at first. During this time easy walking is helpful, but definitely no running or jumping to assist healing.
Then, on the third month, introduce some more activity but no explosive movements or over-exertion. Four months after surgery typically all dogs resume normal activity.
Physical therapy is also recommended after surgery to help your pet get back to its happiest, healthiest self.

My Pet Needs MPL Surgery – Now What?

If your pet needs dog kneecap (MPL) surgery, call or email us. Our veterinary surgeon will work with you and your family veterinarian to understand your dog’s overall health. Our team will advise whether surgery is the best option for your pet. If you decide MPL surgery is the best approach to restoring your pet’s health, the SurgiPet team will promptly schedule the surgery.
Before, during, and after the surgery, you’ll be updated with all the information you need for a safe and speedy recovery. We also offer a wealth of resources right here on our website to help you care for your pet when we’re not there.