Medial Patellar Luxation (MPL)

What is a Medial Patellar Luxation?

Medial patellar luxation (MPL) is a condition in which the kneecap (patella) pops out of its groove. It luxates to the inside of the knee, making the knee unstable. This condition is often diagnosed in small breed dogs, frequently affects both rear legs, and can be either traumatic or congenital (congenital is most common).  MPL occurs most commonly in breeds such as Yorkshire Terriers, Maltese, Papillion, Miniature Poodles, but also can be seen in Labrador Retrievers, Great Pyrenees, and other large breeds.  The severity of the luxating patella (or ease with which it luxates) is graded on a scale of I-IV, with a grade IV being a patella that is chronically luxated.

What does the surgery entail?

The repair consists of several steps: the kneecap is put back in to the groove, the groove is deepened and the surrounding soft tissues and bone are also altered to secure the patella within the groove. Sometime the tibial crest (front section of the shin bone) is transposed to a slightly different location and secured with tiny pins. Most dogs return to full use of the limb very quickly.

What is the Aftercare?

Strict rest is required following surgery to prevent the patella from re-luxating during the healing process. Initially, there should be no running, jumping, or playing. After a gradual increase in activity, full function is allowed by 2 months in most cases.

Are there any Risks or Complications?

Most complications are minor in nature. Re-luxation is rare, but may occur, and often requires an additional surgery. This is of most concern during the first 2 months following surgery, especially in cases with a high grade luxation. If pins were used to transpose the tibial crest, these may need to be removed in 3-12 months.

Overall, some pets recover very quickly with little need for owners’ assistance, but other animals need intensive physical therapy. Lean and fit animals tend to recover quicker than overweight and weaker pets.