Ruptured Cranial Cruciate Ligament in Cats

The cranial cruciate ligament, commonly referred to as the anterior cruciate ligament (ACL), is located within the stifle (knee) joint and acts to stabilize the femur on the tibia.

The ligament can be torn as a result of an acute traumatic event or more commonly it ruptures due to a slow progressive breakdown of the ligament.

When the tear is sudden and complete, lameness may be severe and such that your cat refuses to bear weight on the leg. When the tear is partial or incomplete an intermittent lameness that is more noticeable after heavy play may be seen. Your cat may seem more lame on some days than others.

What to Watch For

Sudden onset of rear limb lameness
Gradual onset of lameness in a rear limb

Diagnosis of Ruptured Cranial Cruciate Ligament in Cats

The diagnosis is generally made during the physical examination. Your veterinarian will want to know whether the lameness occurred gradually or suddenly, whether it is intermittent or continuous, and whether or not it is exacerbated by play.

Your veterinarian will observe your cat at rest and walking and palpate the leg and the knee joint to evaluate for swelling, evidence of pain, thickening, “clicking” on flexion and extension, and the range of motion (flexion and extension).

Specific tests to evaluate the integrity of the cranial cruciate ligament include a cranial drawer test or a tibial compression test which are used to determine if there is increased movement in the joint. The movement in one knee will be compared to the movement in the other rear limb.

Both stifle joints may be radiographed for comparison. X-rays may show joint swelling and various degrees of arthritis depending on the length of time the rupture has been present.

Treatment of Ruptured Cranial Cruciate Ligament in Cats

Cats often do well without surgery. Your veterinarian may recommend that you are strict about confining your cat for six weeks. They may also suggest that your cat lose weight if he is overweight and may prescribe a short course of anti-inflammatory medication.

If your cat fails to improve over a 6 to 8 week period, surgery may be recommended. There are many different surgical options. The basic principle of the surgery is to stabilize the femur on the tibia. This can be accomplished by placing implants within the knee joint, or around the knee joint, or by altering the dynamics of the joint itself. Your veterinarian may prefer a certain surgical technique or suggest referral to a veterinary surgical specialist for consideration of some of the more complex surgical procedures.

Home Care and Prevention

Depending on the type of surgery that has been performed, your cat may go home with a soft padded bandage on the leg. If this is the case, check the toes daily for swelling or discomfort and keep the bandage clean and dry.

If there is no bandage, the incision can be monitored for swelling, redness or discharge. Stitches or staples should be removed at 10-14 days.

Regardless of the surgical technique used your cat should be kept quiet and rested for a period of six weeks, with no jumping on or off furniture. Don’t let your pet go up or down stairs if possible.

Anti-inflammatory medication may be prescribed for the first week following surgery.

After six weeks you can slowly and gradually begin to increase your cat’s exercise until he returns to his normal levels approximately sixteen weeks after surgery.

In cases of acute cruciate ligament rupture there is nothing to prevent the injury from occurring. When the problem is intermittent and more chronic, prompt veterinary attention and treatment can reduce the amount of arthritic damage that will occur within the knee joint.