Canine Cruciate Ligament Injury and Repair
By Jeffrey Godwin, DVM // January 24, 2014
EARLY DIAGNOSIS AND TREATMENT KEY TO SUCCESSFUL RECOVERY
ABOVE VIDEO: Just like people, dogs can rupture their cranial cruciate ligament. When injured, it can be very painful and will likely require surgery. This VetVid video covers the etiology and signs and symptoms of, and treatment options for canine CCL rupture.
BREVARD COUNTY • MELBOURNE, FLORIDA — The knee (stifle) joint of the dog is one of the weakest in the body because of the instability caused by no interlocking of bones in the joint. Instead, the two main bones, the femur and tibia, are joined with several ligaments. Just as athletes (football players, in particular) frequently suffer knee injuries, the dog also has knee injuries.
The most common injury of the knee is a rupture of the cranial cruciate ligament (CCL–in humans it is called an anterior cruciate ligament or ACL). When the CCL is torn, instability occurs that allows the bones to move in an abnormal fashion in relation to one another, causing damage to the joint cartilage.
CAUSES OF CCL RUPTURE
In younger dogs, rupture of the CCL is usually the result of trauma to the stifle joint. In some cases, the ligament may only partially tear, which in many cases ultimately leads to complete tearing of the ligament.
When CCL rupture occurs in older dogs it is most frequently initiated by a progressive degenerative change in the ligament with eventual total rupture. Therefore, the dog does not have to do anything extraordinary to cause the tear. Often they are running in the back yard, plant the foot for a turn, and the ligament breaks.
A special note is appropriate concerning the dog’s weight. Obesity or excessive weight can be a strong contributing factor in cruciate rupture. The ligament may become weakened due to carrying too much weight causing it to tear easily. Obesity will make the recovery time much longer, and it will make the other knee very susceptible to cruciate rupture. If your dog has a weight problem, there are prescription diets that can be used to assist in weight reduction.
Rupture of the CCL is most common in middle aged and older dogs, particularly those that are overweight house pets. Dogs with a ruptured CCL are usually lame and may refuse to bear weight on the affected leg. As the acute pain subsides, most dogs become more willing to bear weight, but some degree of lameness remains.
The most reliable means of diagnosing CCL rupture is to move the femur and tibia in a certain way to demonstrate the instability.
This movement is called a “drawer sign.” It can usually be demonstrated with the dog awake. If the dog is experiencing severe pain, has very strong leg muscles, or is uncooperative, it may be necessary to use sedation in order to examine the joint adequately.
Occasionally, the injury that causes a ruptured anterior cruciate ligament will also result in tearing of one of the menisci or “cartilages.” At the time of surgery, these are examined and removed if necessary.
Small dogs may regain enough stability in the joint to avoid surgery, but in most cases, correction of CCL rupture requires a surgical repair. There are three primary ways to correct this problem.
• Extracapsular Repair–After removing the damaged ligament, the surgeon inserts a replacement ligament and stabilizes the joint so it functions normally or near normally. This synthetic ligament or suture is placed outside the joint capsule.
• Tibial Tuberosity Advancement (TTA)— In this procedure, the boney insertion of the patellar tendon (called the tibial tuberosity) is advanced forward to take the shear forces out of the joint. Once that is done, there is no need for the cruciate ligament any more. This procedure is favored in larger dogs because of the chance that the artificial ligament used in extracapsular repair could break.
• Tibial Plateau Leveling Osteotomy (TPLO)–This is similar to the TTA, except the top of the tibia (tibial plateau) is rotated to remove the shear forces.
Occasionally, small dogs that have a ruptured cruciate ligament will become sound (will no longer limp) even if surgery is not performed. However, in dogs over 30 pounds, progressive, degenerative arthritis will usually develop if the CCL rupture is left untreated. Once these degenerative changes are established, the lameness cannot be corrected, even with surgery.
Following proper and prompt surgical correction and post-operative rehabilitation using today’s techniques, canine CCL rupture repair is highly successful, and the knee joint is sound again in over 85% of the cases. Most dogs walk and run without any lameness, however, some may have a mild limp or lameness associated with cold and damp weather.
ABOUT THE AUTHOR
Dr. Jeff Godwin graduated in the Charter Class at the University of Florida College of Veterinary Medicine in 1980. He has been practicing in Melbourne since 1981. Dr. Godwin enjoys small animal medicine and orthopedic surgery, and is the Hospital Director for his practice, Animal Medical Clinic of Melbourne.
He is a past president of the Brevard County Veterinary Medical Association, the Florida Veterinary Medical Association, and the Melbourne Rotary Club and is the Past Chairman of the Melbourne-Palm Bay Chamber of Commerce. He and his wife Jo have an empty nest except for their Yorkshire Terrier, “Tebow.” In his spare time he enjoys hiking, camping, and backpacking.
Dr. Godwin was selected as the Florida Veterinarian of the Year in 2002 and has served as the Treasurer of the Veterinary Orthopedic Society since 2007.
You can reach Dr. Godwin at The Animal Medical Clinic, 4020 South Babcock Street, Melbourne, Florida, 321-727-2421.