Guest Post: Rupture of the Cranial Cruciate Ligament

Our new guest blogger, Dr. Philip Williams, gives us a clear picture of what a cranial cruciate ligament rupture looks like in a dog. Dr. Williams has his own practice, Companion Animal Hospital, based in Solon, OH.


One of the more common causes of lameness affecting the rear legs in dogs is the partial or complete tear of the cranial cruciate ligament. The cranial cruciate ligament is a dense fibrous band of tissue located in the knee, which is necessary to maintain stability and hence, normal function of the knee. This ligament can tear due to trauma (in people, this is a common football injury), and it may also rupture secondary to degeneration associated with aging.

This injury can occur in any breed and age of dog, but is most commonly seen in active, large breed dogs. It is an uncommon injury in cats, although if seen in cats, they are often overweight.

Dogs with ruptured cranial cruciate ligaments will often present in three different ways. A sudden onset is associated with playing/running hard, acutely becoming lame to the point of non-weight bearing in the affected limb. These animals may progressively get better over the next 3-6 weeks, but will often reinjure the leg at a later time. If not diagnosed at the time of the initial injury, this pattern of getting better and becoming sore again will tend to repeat itself, becoming a chronic intermittent lameness. In those animals that partially tear the ligament, the lameness may be mild and seem to resolve with rest. Only until the ligament completely ruptures does it become obvious what was causing the lameness. It is important to note that up to 40% of those dogs that tear a ligament in one leg will rupture the ligament in the other leg within 18 months.

Charlie a 9 year old neutered male Labrador cross presented for lameness with a duration of 2 days in his right hind leg. He had been running around outside when he injured his leg. He could put weight on the injured leg, but preferred to not if possible. We initially tried 2 weeks of anti-inflammatory therapy.

Normal versus ruptured cruciate ligamentTo the left, the image on the left shows a normal knee, and the image on the right shows a ruptured cranial cruciate ligament, and instability in the knee.

In order to diagnose a tear of the cranial cruciate ligament, a physical exam must be performed. Dogs will often sit with the injured leg not completely under themselves; swelling of the knee and thickening around the joint can sometimes be detected.

The veterinarian will check for instability of the joint, which is best done under sedation, in order to relax the animal and attenuate pain with the procedure. The sedation also allows for X-rays to be taken of the knee to rule out any other causes for the lameness, evaluate the joint for arthritic changes, and look for subtle changes that can be associated with a ruptured cranial cruciate ligament. Arthritis will develop in the injured knee over time no matter what type of treatment is selected.

After 2 weeks of the anti-inflammatory therapy with little effect, we did x-rays and checked the knee for instability. There was no arthritis yet in the knee, but Charlie had a completely torn his cranial cruciate ligament.

Conservative treatment for a ruptured cranial cruciate ligament includes rest, anti-inflammatory therapy, acupuncture, and physical therapy. This approach may work well in dogs weighing 20 pounds and under; however, in bigger dogs reoccurrence of the lameness is almost inevitable with an unlikely return to pre-injury activity, without a surgery to stabilize the knee.

Surgical stabilization can benefit any sized dog, and is usually what is required to return the animal to optimum function. There are a number of surgical techniques used to stabilize the knee (lateral suture, TPLO, TTA), and they all seem to work well in dogs weighing 80 pounds and under, while dogs that weigh over 80 pounds will probably benefit the most from more aggressive and expensive procedures (TPLO, TTA), that involve cutting bone and placing metal plates and screws.

Post-surgical care is extremely important, including: anti-inflammatory therapy, physical therapy, and acupuncture treatment, which help restore the joints back to normal function. Because arthritis will occur, it is highly recommended for joint supplements to be given that contain Glucosamine, chondroitin sulfate, and MSM for the remainder of your pet's life.

Lateral suture technique cruciate ligament repairCharlie weighs 70 pounds and the owners decided to have the lateral suture procedure done. After the surgery he was on anti-inflammatory therapy for another 2 weeks, and was limited to leash walks, no running allowed, for 3 months. It took him about 2 weeks to start putting weight on his leg, and within 1 month he was using the leg normally. About 8 months later he ruptured the cranial cruciate ligament in the left leg, which we repaired in a similar fashion as is doing well now on both surgically repaired legs.

The picture to the right demonstrates the lateral suture technique to stabilize the knee, similar to what was used to repair Charlie’s knee.

Both figures were taken from: Small Animal Surgery, Third Edition, Ed., TW Fossum, Pub., Mosby Elsevier.


Dr Philip WilliamsDr. Phil Williams obtained his DVM from the University of California, Davis. He worked as a large animal veterinarian in both Fresno, CA, and Greeley, CO for five years and then returned to school to pursue a PhD in Neuroscience, where he researched alterations in brain physiology relating to epilepsy at the Colorado State University College of Veterinary Medicine, where he also received advanced training in Anatomic Pathology.

Dr. Williams was a research associate in the Case Western Reserve University School of Medicine department of Neuroscience, and has been practicing small animal medicine at Companion Animal Clinic in Solon OH. He enjoys gardening and relaxing with his wife Jessica, stepson Gabriel, daughter Meadow, dog Moet, and cat Blackie.

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