Dr. Justine Zingsheim-Nadeau
Brookside Veterinary Hospital

I am Dr. Zingsheim. I am the owner and a veterinarian here at Brookside Veterinary Hospital, and today we're going to talk about cranial cruciate disease in dogs, or what a lot of people commonly know as the ACL, and different treatment options and what to look for in your pet.

This is a model of the canine knee. You can see it's made up of the femur, the tibia, and there's a patella, that's our kneecap. Because it's just bone on bone in this joint, there's a lot of instability. There are a lot of ligaments that live inside the knee that help to stabilize it and make it what we call a hinge joint, like a door, just up and down. One of these ligaments is called the cranial cruciate ligament. What they call it in people is the ACL, and that's this ligament right here.

What that ligament does is it helps to keep the knee moving in the hinge joint, so not side to side or forward and back. You can see I can't move the tibia here forward from the femur. Injury to the cranial curate ligament is probably the most common reason for a dog to come into the clinic for limping in a rear leg. Something you might notice at home is the dog might cry out while running and jumping. That's called an acute injury if they injure it right in the moment. There's also a chronic injury where the fibers of this ligament start to degenerate over time and then slowly start to tear away, leading to instability of the leg.

What happens when you notice this in your dog, obviously, you'll come in to see us, and we'll take a look at it. One of the things we will look for is the ability to move this leg forward and backward. That's called a cranial drawer. Again, the ligament serves the purpose of keeping the knee from being able to shift all around. If I were to cut this ligament, meaning that we were to tear it, you can see that I can now shift the knee forward and back, and that's what causes the pain. Instead of the knee moving like a nice hinge, you're going to get it shifting every time the dog uses its leg, and those bones grinding on each other is what causes the pain.

You can also see a secondary injury to the tear. There are two little cushions of cartilage that live inside the joint called the meniscus, and that can damage those cushions and cause secondary pain from the leg shifting on itself. In addition to looking for movement of the femur on top of the tibia, like we talked about with the cranial drawer, we're also going to take X-rays to look at signs of inflammation and arthritis. We also look for positioning of the femur on top of the tibia.

In this image, you'll see that there is a lot of inflammation. That's the white stuff here in the joint. The bones of the knee aren't very smooth. You can see further down there's nice smooth bone. Up at the top here, it's more stippled and reactive, and that indicates that there's been some form of arthritis. So this picture is a great picture of a dog with a cruciate injury. You can also see how the femur up here is sitting much further back on the tibia. It should be sitting further forward.

In comparison to a normal knee, you can see that there isn't all of this inflammation. The bones are a lot smoother, and the femur is sitting a little bit further forward. There are a lot of different treatment options for the repair of this injury. The most common is a surgical repair called a tibial plateau leveling osteotomy (TPLO), a super fancy name for a procedure that gets rid of the need to have a ligament.

We can't repair the ligament. Unfortunately, there's no way to suture it back together or anything like that. So we have to be able to stabilize the knee so that it's not shifting like that when the dog is moving. The way we do that is we make a cut, a curved cut into this lower bone, and then what we'll do is actually shift the bone so that the femur sits further forward on this tibia, and then we hold it in place with a metal bone plate. By doing that, you'll see that I can't get the knee to shift forward anymore, so it'll stabilize the joint for the dog when he's moving. After surgery, you will see how the knee looks with the new placement. You can see the bone plate that we talked about and the cut that we had to make. Then you'll also see how the femur is now sitting further forward on the bone like it should. This is how the knee is stabilized after surgery.

Surgery is really the only definitive way to fix this particular injury. Alternatively, you can try rest and exercise restrictions. The caveat to that, though, is that it's 50/50 if a dog will improve or not. Some dogs will continue to be limp, and some dogs will improve, but there will always be a component of lameness, no matter what we do. Surgery just gives you the best chance to get back to a normal, happy, running, jumping, active dog.

That's what is involved in a TPLO. This is a procedure that we can do here. It's one that I perform myself. Although I'm not board certified, I've taken a lot of classes and done the procedure many times, so it is something we can accomplish for you here. We do also have a mobile board-certified surgeon that can come in and do it if you would prefer that. If you have more questions about this procedure or recovery period, there's a lot more we can go into, so feel free to contact us if needed.

If you still have other questions and you'd like to reach out to us, you can call us directly at (253) 857-7302, or you can email us at [email protected]. But please do reach out, and we'll get back to you as fast as we can. Don't forget to follow us on social media Facebook, Instagram