On Saturday the clinic was very busy. We had our scheduled appointments along with two emergencies. Those two emergencies were limping dogs, which ended up being anterior cruciate ligament ruptures or cranial cruciate ligament ruptures.

The first dog I had seen before with the same limp unfortunately now it had gotten worse. My initial visit with the dog, a 100 lb Bullmastiff, he was still using the leg but had a noticeable limp on the right hind. Palpation and flexion showed minor discomfort in the knee. Attempts to exhibit a drawer sign on the dog were met with a relatively painful but stable joint. This suggested to me a partial tear or strain of one of the cruciate ligaments in the knee. So we sent the dog to physical therapy. However today the poor thing was only toe touching his leg and barely using it. Repeating the tests showed more discomfort in the knee as well as a cranial drawer sign. I sent the dog to an orthopedic surgeon for repair, the same orthopedic surgeon that had fixed the left hind knee a couple of years ago.

The second dog, a collie mix about 40 lbs, came in not using the leg at all, completely holding the leg up. Attempts to palpate the leg were rather difficult as the dog decided to lunge at me every time I even came close to the knee. Palpation of the quadricep muscles were also met with snarling and snapping. So we sedated the dog, upon sedation and examination of the knee a complete drawer sign was noted. This means the dog has a complete tear of the cranial cruciate ligament allowing the tibia to slide back and forth along the femur. Very painful! This dog was also sent to an orthopedic surgeon for cranial cruciate ligament repair.

So what is the anterior or cranial cruciate ligament anyway?

Here is a picture of the normal knee of a dog taken from Hills Veterinary Atlas. Click on it for a larger view. You are looking at the knee from the front. Do you see on the inside of the knee how there are two ligaments. these ligaments cross. For the Anterior or Cranial Cruciate ligament the top part of the ligament attaches to the femur at the back of the knee and the bottom part of the ligament attaches to the tibia at the front part of the knee. the caudal or posterior cruciate ligament does the opposite so it criss crosses with the anterior ligament. This allows the knee to be able to bend however prevents it from sliding back and forth stabilizing the joint. When one of these ligaments tears or ruptures the knee becomes unstable and is allowed to slide back and forth. This will set up some major inflammation and if left untreated will cause some major degeneration and arthritic changes in the knee. A partial tear can be medically managed for a few months allowing the ligament to heal. Treatments such as underwater treadmill therapy (Underwater Treadmill info) , passive range of motion exercises, electrostimulation, chiropractic, acupuncture and eventually quadricep muscle building exercises all play a role in helping heal a partial tear. Little dogs meaning under 30 lbs can sometimes even with a complete tear be managed comfortably with this type of treatment. However, dogs over 50 lbs or dogs with a very active lifestyle more than likely will require surgery to repair a complete tear.

Here is some more info on Cranial Cruciate Ligament Tears…

TPLO Surgery - Repairing Your Dogs Bum Knee
Big dogs have knee problems, too
Anatomy of the Cranial Cruciate Ligament
Surgical Repair Options for Cranial Cruciate Ligament Repair
Canine Cruciate Injuries in Dogs
Some Common Human Injuries Also Common In Dogs