Old Ridge Vet Hospital: A Dog Knee Joint
Why we do so many knee surgeries and what it means for your pets.
We’ve all heard of someone who’s had an ACL tear. If you follow the NFL or the NBA, there’s a pretty good chance you’ve seen someone have that injury. If you’re a middling middle-aged “athlete” (like yours truly), there’s a pretty good chance you know someone personally who’s experienced it.
In humans, the injury is usually a traumatic one. It’s the result of sudden changes in direction, stopping suddenly, landing incorrectly, or even a direct impact to the joint.
In dogs, however, traumatic injuries make up a smaller percentage of ACL tears. Dogs often tear their ACL as a result of long-term degenerative changes in the knee. What looks like an acute injury many have been brewing for a long time.1
What happened?
When your dog tears their ACL, they’ve lost a ligament crucial to stabilizing that joint. After the injury, you’ll often see is a little wiggle to the injured leg when they shift their weight onto it. Your pet will try to use their muscles to better balance on that injured leg, but it doesn’t work quite as well as the ligament did.
The other thing that can happen is damage to the meniscus. The meniscus is a piece of cartilage in the joint that has important functions in shock absorption, stability, and lubrication. Damage to the meniscus can make a dog feel like there’s a rock in the joint. It’s painful.
Not every dog that tears their ACL will have an injury to the meniscus, but it’s no fun for the roughly one-third of dogs that will experience both.
How can you tell?
I have a pretty good eye for lameness. That sort of thing happens when you look at ten or twenty animals a day, five or six days a week, for a decade. It’s not magic, it’s practice.
When I palpate your dog’s back legs, I can feel laxity in the joint, crepitus, or bony changes in and around the knee. The laxity is in the form of the “drawer sign” or “tibial thrust,” which is where the shin bone will slide forward abnormally relative to the the thigh bone. Crepitus is a grating, crackling, or popping sensation in the joint, often due to rubbing of bone on bone or on roughened cartilage after an injury. And the bony changes may be a thickening of the interior aspect of the top of the shin bone.
But the way to confirm the diagnosis is with an x-ray. The physical examination makes us suspicious, but the imaging confirms it. If I note those things on a physical examination, I will recommend an X-ray of your dog’s knees.
I’ll review the X-ray and can usually tell if the ACL is torn, but I like to have our board-certified surgeon review the X-rays before I fully commit to the diagnosis. It’s Dr. Lynch’s specialty. He’s the best surgeon I’ve ever seen and he loves those knees.
Why do we need surgery?
The ACL isn’t going to heal on its own. The meniscus isn’t going to heal on its own. The increased laxity in the joint will hasten the onset of arthritis. The decreased use will lead to muscle atrophy. Overall, more pain and less movement for your dog.
Pain medications can help manage the discomfort, but it doesn’t fix the problem.
TPLO surgery fixes the problem.
But it doesn’t seem to bother him?
Pain isn’t as simple as “absent” or “agony.” Something can hurt without being totally debilitating. You can have a mild headache that slightly dampens your mood or you could have a migraine that ruins your weekend.
If the limping is visible to me or another veterinarian, it’s safe to assume that there’s a degree of ouch happening.
What about the other leg?
About 60% of dogs that tear one ACL will tear the other. That’s because so many of these injuries are related to degenerative changes and not just acute trauma.
If your dog hasn’t already torn both, there’s a pretty good chance that they will. That’s not a reason not to do the surgery, though; if a pet’s in pain, we shouldn’t wait to do something about it.
But my friend’s dog never had the surgery and did fine?
It’s possible that scar tissue stabilizes the joint and the pain subsides. But it doesn’t happen often.
What happens more frequently is that our stoic pets just work through the injury without complaint. They’re still in pain, they just hide it.
And instead of slowing down at 12-years old, the dog started slowing down at nine years old. That’s harder to quantify. It’s difficult to look back and say that if we’d fixed an injury that happened at six, a pet would’ve lived longer.2
What about a brace?
It’s better than nothing, but not by much. It’s about 5% better than nothing. Even the computer-generated samples don’t show great improvement.3
Braces don’t make enough of a positive impact to warrant consideration.
What is done in the surgery?
The surgery we perform at ORVH is the tibial plateau leveling osteotomy (TPLO). In order to fix the stabilization issue, we take the steep slope of the tibia (the shin bone below the femur) and cut the top off, the plateau, rotate the bone so it’s flatter, and plate it back into place.
“Tibial” is the shin bone, “Plateau” is the top of the bone that forms the joint surface, “Leveling” is the rotation to decrease the angle and flatten it, and “Osteotomy” refers to the cut into the bone itself.
T-P-L-O.
When we do the TPLO, we are able to look into the joint and evaluate for a meniscal injury. If we find one, we can fix it by “releasing” the meniscus. Essentially, we cut the damaged part away.
There are other surgical options you might find if you’re the Googling sort. One is the tibial tuberosity advancement (TTA). I don’t know many folks who even do that surgery these days. It’s a reasonable procedure, but the TPLO provides better outcomes.
The other one I frequently hear about is the lateral fabellar suture (LFS) or the “tightrope” procedure. The goal is to stabilize the joint artificially by placing a strong suture around the fabella (the small bone behind the knee) and then extending the suture to the tibia. The idea is that the surgery prevents the forward movement and internal rotation of the tibia relative to the femur (thigh bone).
The trouble with it is that it doesn’t work all that well. It doesn’t offer the opportunity to fix a meniscal injury the same way the TPLO does. It doesn’t work as well for active or large dogs. And it doesn’t always resolve the pain in the joint.
It’s short of ideal from the veterinarian’s perspective too: we did a surgery and your dog is still limping? Definitely not the desired outcome.
The TPLO fixes the problem of instability and relieves the pain.
What’s the recovery like?
The recovery process is eight weeks. We say that surgery is the easy part because we’re done in a few hours, but recovery lasts two months.
The cut we made in the bone needs time to heal. The plate doesn’t replace the bone’s strength, it just holds the bone in the perfect position to heal the way we want.
A dog that jumps on or off the couch or bed, runs around, or is subjected to stairs or slippery surfaces can catastrophically injure their healing leg.
A dog that doesn’t have a cone for the two weeks post-op can introduce disastrous infections to the incision site and joint. Some of the worst outcomes we’ve seen are because a dog wasn’t made to wear the cone.
That’s why we provide intra- and post-operative antibiotics. It’s why we send your dog home with a cone. That’s why we provide pain medications and mild sedatives to help keep your dog comfortable and quiet. That’s why we help you put a specialized support harness on your pet before you leave.
But he hates the cone!
I’m sympathetic, but I assure you he will hate a nasty infection of his newly repaired knee much more than he will hate a fortnight of looking silly.
Two weeks with the cone can help us avoid major disasters.
What’s the Maven collar do?
When you schedule an ACL surgery at ORVH, I’ll recommend that you go home with a Maven collar. The Maven collar is a canine activity tracker that uses a combination of artificial intelligence and human monitoring to help you manage your pet’s recovery process.
The data of the pet’s activity is sent to our technicians, who receive alerts if your dog exceeds a level of activity we associate with a positive outcome in recovery.
You’ll get a phone call from us asking how we can help. If we detect licking, we’ll ask if we need a better fitted cone. If we see too much running and jumping, we’ll ask if you need more sedatives. If there’s too little activity, we’ll ask if you need more pain medication.
It might feel a little Big Brother-y, but the idea is that it helps you with the recovery because now you have technology and technicians and team of people helping you monitor the outcome.
It’s not a replacement for your judgment, it’s an adjunct to it. It lets us help you.
I called another hospital and it costs less, why?
Because when I give you an estimate, I give the estimate for the whole process. The surgery, the medications, the follow-up appointments, the recovery X-rays.
I want the answer to include everything we need to do and the entire cost of the surgery and everything associated with it. I don’t want you skipping crucial medications or follow-ups because of the expense. I don’t want you surprised by charges. We need to do everything right in order to get a good outcome.
So you don’t get a “price for the procedure,” you get a price for the entire process from diagnosis to eight weeks post-op. You’re all in from the outset —no surprise charges.
I saw you advertised about a discounted TPLO surgery for pets participating in a research study?
That’s true, but the study additions are paused for now. We have to catch up on the pets enrolled as subjects until we consider adding more.
If you’d like your pet to be considered, please let me know. I want to caution that because it’s a research study for scientific publication, we have to be rather strict about the subjects we are allowed to enroll. We need a very consistent group of subjects in order to make the strongest conclusions at this stage.
So now what?
Before the surgery, we need x-rays to confirm the diagnosis and bloodwork to ensure that we’re healthy enough for surgery.
Dr. Lynch is a residency-trained and board-certified veterinary surgeon who comes to Old Ridge Vet to do orthopedic surgeries. We will schedule with him and with you to find a date that works for everyone and get it on the books. All the surgeries are done right here at ORVH.
We take a deposit when the surgery is booked and that goes towards the surgery. If you cancel more than 72-hours in advance of the surgery, you get the deposit back. If we cancel the surgery for any reason, you get the deposit back.
If you’d like to book a consultation or teleconsultation, just add yourself to our schedule here. You’re welcome to add yourself if you just want to talk and learn more about the procedure.
As always, please let me know if you have any questions!
In dogs the equivalent ligament is called the “cranial cruciate ligament” (CrCL) rather than the “anterior cruciate ligament” (ACL) because of the directional anatomy of a four-legged creature. For this essay, I will use ACL to refer to the ligament in the dog.
And since we aren’t terrible human beings we don’t ever say things like, “If you’d done the surgery I recommended three years ago, I definitely think he’d be walking way better today.”
This study, troublingly, did not include a control group.