What is the Cruciate Ligament?
The cruciate ligament is a ligament that stabilizes the knee of the hind leg. In humans, it is known as the anterior cruciate ligament or ACL, while in pets it is known as the cranial cruciate ligament or CCL. A ruptured ACL is a fairly common and very painful injury among human athletes. Dogs are susceptible to a ruptured CCL due to the hard running and stopping they may do in the course of normal play.

What exactly does the CCL do?
It is important to understand the anatomy of the bones in the hind leg in order to understand this condition. The femur is the largest bone of the hind leg and it attaches to the pelvis. The femur rests on the tibia and the knee joint is stabilized by the joint capsule, surrounding muscles and ligaments, one of which is the cranial cruciate ligament. This ligament prevents the joint from bending too far the wrong way or hyperextending. It also prevents rotation of the joint which is a twisting motion of the knee and prevents the tibia (shinbone) from sliding forward. When the CCL ruptures, the joint becomes unstable and the femur is allowed to move freely over the tibia, pulling and tearing the joint capsule of the knee.

Ouch, this must be painful!
This type of instability in the knee is very painful and can cause joint swelling and hemorrhage. It can also cause abnormal wear of the bone and cartilage found in the knee, leading to long-term problems such as arthritis. Animals suffering from this problem may be lame for a few weeks or months and then may seem to get better only to develop a more chronic progressive lameness that never resolves and worsens with exercise.

When football players tear their ACL they go to the locker room and get an MRI. How is it diagnosed in pets?
Veterinarians generally diagnose this problem by examining the gait or walk of the animal, feeling the joint, and by checking for abnormal mobility of the joint called the cranial drawer sign or cranial tibial thrust. Using this test, the joint can be manipulated forward and backward, a movement normally prevented by a healthy CCL. After the problem has been diagnosed, x-rays are usually taken to determine the extent of the damage in the joint and to make sure there are no underlying problems in the knee.

How do you treat a ruptured CCL?
Surgery is the only corrective measure for ACL injuries. Surgery stabilizes the knee allowing to regain normal motion and thereby reducing, but not prohibiting, the formation of arthritis. If surgery is not performed, progressive arthritis will occur and the lameness will worsen with time.

We repair ruptured CCL's on all sizes of dogs at our clinic with a surgical procedure called a lateral fabellar suture repair. As you would expect with knee surgery, there is some post operative pain intitially but the pet is always sent home with pain medication after surgery.

What to dogs do after surgery?
We always send our CCL patients home on a rehabilitation schedule to help the pet return to a more normal function of the leg without over-doing it.

In the first week we allow short, slow, and controlled leash walks on level surfaces with passive range of motion exercises. We also recommend placing an ice pack on the knee for 10 minutes twice per day. By the second week, we increase the leash walks to 10 minutes total a day. Every week we increase the total time a dog is leash walking. After 10 weeks, we recommend very slowly introducing the dog's regular routine. It may take up to 3 or 4 months for the pet to fully begin using the leg.