Treating Cranial Cruciate Ligament Tears

Rear limb lameness in the dog and cat is common, as both species are generally active and athletic. While hip dysplasia and hip arthritis definitely get a lot of coverage in the press and by breeders, the knee is often the culprit when an owner sees an acute (sudden) and severe lameness. Sometimes the pain is from an injury to the structures that form the knee, or pain may result from conformational problems in the pet’s anatomy.

This article will focus on the one of most common knee pain culprits seen in our practice: Cranial Cruciate Ligament  (CCL) tears. We keep our surgeon busy with the repair of this problem. Luckily, CCL tears may be resolved by a single surgical procedure and following up with a period of physical therapy and restricted exercise. Pets normally return to full activity within weeks to months, and even big dogs are usually weight-bearing and walking pretty well a week after surgery!

CCL tears, sometimes referred to as “ruptures,” are generally seen in large breed dogs like active, sometimes obese, Labrador Retrievers chasing a squirrel or tennis ball, but cats may have this injury too. The classic scenario is sudden inability to bear weight on a rear leg, or an event when the pet is very active or leaping/jumping, then cries in pain and pulls up very lame. In dogs, ruling out Lyme Disease is important with sudden onset of a swollen, painful joint.

In certain instances (very small pet, incomplete tear as opposed to full tear) CCL injury may improve with rest of several months, but, particularly with full tears and/or larger pets, the instability that results from the injured ligament causes inflammation, pain, and finally arthritis in that knee. Usually these pets have an intermittent limp that responds to anti-inflammatories (like Rimadyl) and rest, but which re-surfaces, especially during or after athletic endeavors. This injury may affect both legs. Typically a dog that injures one CCL will injure the other CCL (on the opposite leg) within 1 year.

Diagnosis of CCL injuries can be difficult, since the CCL is a soft tissue structure and does not appear very well on x-rays, and tense, painful pets can use their muscles to falsely stabilize the knee during a veterinary exam. Diagnosis is usually made with a sedated exam to manipulate and take x-rays of the knee. By manipulating the knee, most surgeons can detect the tell-tale “drawer” sign. This happens when pressure is applied to both sides of the knee joint, and instead of the joint remaining stable, the tibia, which is the bone comprising the lower part of the joint, thrusts forward -- like a drawer in a chest of drawers.  In some cases MRI is useful, albeit far more expensive. The MRI gives a superior view of the soft tissue structures in the knee (these just don’t x-ray very well), but with symptoms, swelling, and drawer sign most surgeons can make a diagnosis.

There are several surgical options and the pros and cons vary depending on your pet’s size, activity level, and anatomy. Our board certified veterinary surgeon, Dr Tibor Lazar, has videos on his website explaining the injury and repair in detail: http://lazarveterinarysurgery.com. If your pet has a limp, he/she is doing this from pain; it is not a habit or ploy for attention. Ask your vet to check it out! Even if surgery is not an option, as in CCL repair, your pet’s quality of life may be enhanced by pain relief, acupuncture, or physical therapy.

Submitted by Dr. Jann Elliott, Palisades Veterinary Clinic (www.palisadesveterinaryclinic.com/)