Veterinary Wellness Blog

Don’t let a bum knee bum out your pet (Part I)

August 2, 2013

In this first of two articles about knee injuries and issues, we will be talking about medial luxating patellas (MPLs), or in less medical speak, knee caps that pop out of place.  This condition can be very common in smaller breed dogs, but can also occur in other pets and larger dogs.

Often as a pet owner, the first sign of an issue that you may notice is that a pet may be running around and suddenly skips a step or starts running with only 3 legs, then a few steps later they may be back to running around like normal.  Other times you don’t even notice and issue and the vet is the first to identify the problem.  In severe cases, the knee cap may luxate out of position and remain out, causing discomfort and a lasting limp which may cause you to seek medical attention.

The knee cap, or patella, usually sits in a groove on thigh bone or femur.  In some dogs, this groove is not deep enough, and the forces of moving the leg cause the ligaments and patella to move out of the groove.  About half of the dogs that have one leg affected will have both legs affected.  There are 4 grades of MPLs based on their severity.

• Grade 1 means that the kneecap can be moved out of place on examination but it goes back into its regular position.
• Grade 2 means that the kneecap can be moved out of place on examination, and then remains out of place.
• Grade 3 means that the kneecap is out of place all the time but can be moved back into place, but doesn’t usually stay there.
• Grade 4 means that the kneecap is out of place all the time and cannot be put back into place.

Depending on the signs, symptoms, and grade, surgery may be recommended.  Grade 3 and 4 usually require surgery, and it may be recommended for grade 2 as well since a knee cap that stays out of place can lead to arthritis, bone deformities, and ligaments that do not function properly which causes a limp or discomfort.  A discussion with the veterinarian and radiographs or x-rays may be beneficial to determine if surgery is the right option for your pet.  Even if surgery is not recommended, short or long term anti-inflammatory pain medication may be prescribed.

If surgery is elected, there are a number of surgical techniques that are used to repair the problem.  Often the groove on the femur is deepened.  The joint capsule may be tightened to provide more stability.  The attachment point of the patellar tendon may be moved to provide proper alignment.  Other techniques may be utilized depending on the case and surgeon’s preference.  We here at Heritage Animal Hospital have an orthopedic surgeon come in to perform the procedure.  More information can be found here.

If your pet seems to have a bum knee, give us a call and we can help find a proper diagnosis as well as come up with a treatment plan that works for your pet.  Stay tuned for next month’s article about ACL injuries to learn about other knee issues.