Aerowood Animal Hospital

2975 156th Avenue Se
Bellevue, WA 98007





 Knee Surgery (FAQs) Frequently Asked Questions


1. What is the Cranial Cruciate Ligament?

The Cranial Cruciate Ligament, also sometimes called the Anterior Cruciate Ligament, is a tough band of tissue that connects the two main bones of the knee (stifle) joint. Specifically, the upper bone of the joint is the Femur and the lower bone of the joint is  the Tibia.The Cranial Cruciate Ligament connects the posterior (rear area) of the Femur, to the anterior (front area) of the Tibia.This ligament helps prevent excessive motion between these two bones. Rupture of this ligament is the most common orthopedic injury in dogs and results in a painful, unstable joint. If left untreated, this injury leads to degenerative joint disease (arthritis).


2. Why did my dog rupture this ligament?


Although this is the most common orthopedic injury in dogs, it is still not completely understood why this ligament ruptures. Many theories have been proposed. Certainly, trauma can cause the ligament to rupture - this is the most common reason for ligament rupture in humans. In dogs, however, this does not seem to be the most important cause. Indeed, most of the ruptured ligaments that we see are not sudden ruptures. Instead, they are partial ruptures that lead to full ruptures. In most cases when the joint is opened, even in a "fresh rupture", there is obvious evidence that there has been ongoing arthritis in the joint, indicating abnormal movement (and wear and tear) for a prolonged period of time.


3. Why does my dog need surgery?


Unfortunately, if your dog ruptures the Cranial Cruciate Ligament, surgery is the only real option. When the ligament is torn, there is a shearing force that results when your dog tries to bear weight on the leg. This shearing force makes the femur slide backwards on the surface of the tibial plateau. This abnormal movement sets up excessive wear and tear on the cartilage surface, which induces further arthritic change in the joint. Additionally, this abnormal motion frequently damages the cartilage pads in the joint, known as the menisci. Damaged menisci also leads to further arthritic change.


4. What surgeries are currently being done?


At present, there are four surgical procedures being advocated - TTA, Tightrope CCL, Lateral Suture Procedures and TPLO.


5. I have been told that my dog may have the same problem later on the opposite leg. Is this true?


The statistics tell us that 35-40% of the dogs will suffer rupture of the cruciate ligament in the opposite leg. It is probable that the underlying arthritic change that lead to the first rupture has already started in the opposite leg.


6. What can I do to lower the chance that my dog will need surgery in the opposite leg?


There are several things that may help. Obesity is often blamed as a contributing factor. So, if your dog is overweight, then a proper diet program may help. If you are not sure if your dog is overweight, ask your doctor. Most veterinarians will give your dog a "body condition score" and explain what that means.Your doctor will also give you suggestions to help your dog lose weight. Many dogs act like "weekend cowboys". They rest all week and on the weekends, when the parents are home, they over exercise in the back yard, possibly leading to joint damage.The same thing frequently happens to people. It is important that our muscles be trained for the activities that we plan to do. It is important also to stretch our muscles before vigorous workouts.Talk to your veterinarian about how you can help train your dog, rather than just turn him or her loose.