Cruciate Ligament Injury

                                                       Pet Tales
                                                              by Barry B. Burtis D.V.M.
Cranial Cruciate Ligament

Bruno was a 2 year old male Rottweiler who was brought to the animal hospital because he was lame on his left rear leg. Julie was a 9 year old spayed female Cocker Spaniel examined for the same problem, except it was her right rear leg that was affected. Bruno was young, athletic and an ideal weight for his size. Julie, now considered a senior aged pet, weighed 17 kg., at least 3-5 kg. heavier than her ideal weight.

The day before his visit, Bruno had gone out in the leash free park playing and romping with some of his best buddies. His owner had been chatting with another dog owner, while Bruno was off with his friends. He was unaware that anything had happened, but when Bruno came back he was holding up his left rear leg and would only walk on his three other limbs. There really had been no change since it happened. He had eaten his meals, gone out for bathroom duties, just about everything as usual, except he did everything on three legs. He was a bit reluctant to let his owner examine the leg but did not appear to be terribly painful with it and his owner could find no cause for the problem.

On the other hand, Julie's problem had been more gradual in onset. Her owner thought it had been probably been about 2 weeks ago that she had noticed Julie favoring the leg. Also, although not using the leg normally, she was not holding it up like Bruno. Rather, she just would not fully bear weight on it, causing her to hobble along as she walked. Just like Bruno, Julie seemed otherwise normal in body functions and behaviour. She also showed no pain or discomfort when her owner felt up and down the leg.

Although each case had quite a different presentation, when they received an examination by their veterinarian, the same problem was suspected for each patient. There were some other tests planned to confirm the diagnosis but the tentative diagnosis in each patient was a torn or ruptured anterior (or cranial) cruciate ligament.

A dog's cranial cruciate ligament, just like our own, is found in the knee joint. It stabilizes this joint by limiting internal rotation and preventing the tibia ( the bone running from ankle to knee) from moving too much forward relative to the femur ( the bone between the knee and hip). It prevents hyper- or over extension of the knee joint. It can be injured acutely as a result of trauma or chronically as a result of more gradual degeneration of the strength of the ligament. Problems can develop as a result of either complete or partial rupture of the ligament. It is one of the most common causes of hindlimb lameness in dogs. Injury to the ligament is a major cause of degenerative joint disease (arthritis) in dogs. Cruciate disease is quite uncommon in cats.

It occurs most commonly in dogs older than 5 years of age, although in large breeds it often occurs between 1 and 2 years of age. It can affect any breed of dog but Rottweilers and Labrador Retrievers have increased incidence of cruciate rupture when they are less than 4 years of age. Female dogs may have slightly more risk to have the problem.

Diagnosis of ligament rupture is made when cranial drawer motion can be demonstrated in the knee joint. This abnormal motion or movement between the bones that meet at the knee joint will only occur when the ligament has been torn or ruptured. Sometimes a veterinarian is able to detect this during the routine physical examination of an animal. It may be necessary to sedate or anesthetize a patient in order for them to be relaxed enough to make the diagnosis.

Surgery is the treatment of choice for dogs who sustain this injury. It returns stability to the joint most quickly, speeding recovery from the injury. It prevents further degenerative changes in the joint and therefore reduces arthritic development in the knee. There are several different surgical techniques used for the repair. No one method seems superior to the others. Some methods make use of implants to replace the torn ligament; others transplant or reposition other body tissues located near the knee to accomplish the same effect.

After surgery, good nursing care and physiotherapy will help the patient's recovery. Some exercise restriction is necessary while healing occurs. Non-steroidal anti-inflammatory drugs and analgesics may be used to control post-operative discomfort and arthritis. Alternative drugs like glucosamine and chondroitin sulfate may help limit cartilage damage and degeneration. Most patients require 2-4 months to fully rehabilitate. Unfortunately, 20%-40% of dogs who develop this problem in one knee will experience the same problem in the other knee within 17 months.

After recovery, Bruno was probably out bragging to his buddies that he had suffered the same knee problem that had afflicted hockey players, Grant Fuhr and Pavel Bure and he would be back just like they were. Practical Julie, on the other hand, embarked on a weight management program to lessen future complications from her knee injury.