Damage to the anterior cruciate ligament (ACL) in the knee is a well-known source of disabling injury among humans. It can strike elite athletes or weekend warriors, and usually requires surgical repair. The same could be said of dogs. ACL-like injuries are among the most common orthopedic injuries most veterinarians see. In dogs, this ligament is referred to as the cranial cruciate ligament (CCL).
A ligament is a form of connective tissue that connects one bone to another. The CCL joins the thigh bone (femur) to the lower leg bone (tibia) at the knee joint. The knee is a complex structure that absorbs shock and provides mobility in numerous dimensions. The CCL plays an important role in stabilizing the knee joint, while allowing it the flexibility it needs.
Virtually any breed of dog may be affect by a CCL injury. Even so, certain breeds are more prone to these injuries than others. Among the more susceptible breeds are Labrador retrievers, poodles, golden retrievers, bichon frises, German shepherds and rottweilers. Other factors may influence the likelihood that a given dog will succumb to this form of injury, too. Among them: being overweight, being physically inactive (followed by a sudden enthusiastic burst of activity), being a male dog who was neutered before five months of age, being a dog with a conformational abnormality in the rear legs, and having had a ruptured CCL in the opposite knee within the last two years.
Dogs with this injury will experience severe pain and difficulty walking. The joint may swell and become unstable. Leaving this injury untreated could lead to chronic lameness and irreversible joint damage. CCL injuries are among the leading causes of progressive osteoarthritis of the knee in dogs.
Fortunately, as in humans, we’ve made great advances in the diagnosis and treatment of these disabling injuries. It’s now possible for your veterinarian to surgically repair the ligament, with a reasonably high expectation of full recovery.
Causes and Prevention
As noted above, it’s important to maintain your dog’s body weight within a healthy range. Being overweight or obese places undue strain on all your dog’s organ systems; not least his or her joints. Being physically fit and active may also help protect against osteoarthritis. Although we used to think of osteoarthritis as an age-related disease of “wear and tear” to the tissues of the joints, we now know that exercise is one of the best remedies against the progressive degeneration and inflammation associated with arthritis.
Symptoms and Diagnosis
Symptoms of possible CCL injury include lameness in one or both hind legs, limping, or avoiding the use of one particular leg, limping that improves with rest, strange posture, difficulty getting up after a long rest, and swelling around a knee joint. Your veterinarian can diagnose this common injury with a relatively quick and simple physical exam. He or she will perform an assessment of the knee’s flexing capacity. This procedure is called a “cranial drawer instability” test. To confirm a preliminary diagnosis, your veterinarian will likely order an x-ray of the affected joint or joints as well.
Treatment usually require surgery. Rest, or what is called “conservative management,” typically does not give long-term resolution and often leads to further damage and pain once normal activity is resumed. Therefore surgery is typically the best course of action. There are many options for surgical repair. Procedures can vary based on surgeon preference and size of patient. As with humans arthroscopic evaluation of the stifle (knee) results in less pain and trauma to the joint and therefore quicker return to normal function. Proper rest and rehabilitation also can help with a speedier recovery.