knee injuries in dogs

Molly, a yellow Labrador, was napping in her usual spot in the backyard. Suddenly, a cat rustling in nearby bushes woke her and she set out in hot pursuit. As the 9-year-old dog raced up several concrete steps after the feline, her knee caught on the top step and sent her tumbling to the ground, howling in pain.

Each year thousands of dogs, like Molly, sustain knee injuries while running, jumping or even walking.  Most injuries to the back legs involve the cranial cruciate ligament (CrCL), which happens when the knee twists the wrong way and causes the joint to become unstable.

Experts say this kind of injury is the No. 1 reason for hind limb lameness in large breed adult dogs, like Labradors, Golden Retrievers and Rottweilers.  If your dog experiences a traumatic accident and doesn’t put weight on the injured leg within 36 hours, see your veterinarian. Left untreated, a ruptured cruciate ligament permits the tibia to move forward and out of alignment with the femur. This condition can eventually lead to severe — even crippling— arthritis of the knee joint.

To confirm a ruptured CrCL, your veterinarian will perform a cranial drawer test. The test involves moving the shin bone (tibia) forward in relation to the thigh bone (femur.) If the shin bone moves forward, the ligament is torn.

More than half of the patients that ruptured one knee will also rupture the other. That’s because while recovering from the first injury, additional stress is placed on the “good” leg, which can lead to injury. Some veterinarians say there’s also a hereditary predisposition in certain breeds to have ligament degeneration. Old age can be yet another factor because ligaments are more brittle and break easier under stress.

A Patellar Luxation is graded on a 0 to 4 scale.

	Grade One  The kneecap easily pops back in on its own. Normally dogs at this stage don’t show any signs and the condition is discovered during a routine physical exam.
	Grade Two  The dog shows signs of discomfort by yelping or limping while the kneecap is out of place. The kneecap will pop back into place if the dog stretches its leg.

	Grade Three  The kneecap is out of joint most of the time but upon examination can be pushed back in.
	Grade Four  The kneecap has popped out and the only way to get it back in is by surgery.

Repair Procedures

To repair a torn cruciate, there are several different surgical procedures. Which technique is performed simply boils down to a veterinarian’s preference.  One method, called Tibial Plateau Leveling Osteotomy (TPLO), rotates the top of the tibia, so that when the femur moves against the tibia, it stays put. Some surgeons say this procedure helps patients recover more quickly, experience less arthritis and have better overall function.  Regardless of the surgical technique, recovery takes six to eight weeks.  By this time about 80 percent of normal function will have been regained. In two to three months most patients will be back to normal.

This newsletter is intended to offer general information only and recognizes that individual issues may differ from these broad guidelines.  Your pets specific issues should be addressed with a veterinary professional familiar with the details of the problems. Copyright 2002 © CreativeMinds Publications and Lakeside Veterinary Clinic.