When a dog damages a cruciate ligament in their back leg, the vet may suggest TPLO surgery. But what do those four letters mean and what are the implications for the dog? This article aims to demystify the TPLO procedure, answer frequently asked questions, and help owners understand what TPLO recovery means for them and their dog.
TPLO is an abbreviation, and the letters stands for:
In other words TPLO is a neat way of saying "creating a new, flatter angle at the top of the shin bone."
But why do this? The answer is to improve the way the femur (thigh bone) hinges with the tibia (shin bone) and make the knee joint stable again. For those still scratching their head, read on to get the full picture.
Understanding the nature of the problem, makes it easier to understand the elegant solution that TPLO surgery offers. So let's start at the beginning with 'what is a ruptured cruciate ligament', which is the reason for this surgery.
The cranial cruciate ligament (CCL) is the same as the anterior cruciate ligament in people (ACL). For sports people and athletes, rupture of the ACL is a common injury and the same is true for dogs. However, the solution is different in dogs to in people (after all, we walk on two legs whilst dogs walk on four.)
The CCL is a piece of wonderful engineering which allows the knee to hinge backwards and forwards.
The knee joint is supported by a number of ligaments and tendons. These are tough bands of fibre that act like hausers, linking bone to bone and bone to muscle. The cranial and caudal cruciate ligaments form an "X" shape inside the knee (crossing over each other, hence the name "cruciate") which links the thigh and shin bones in a hinge. As well as keeping the bones lined up, when the dog takes a step the cruciate ligaments absorb forward thrust on the shin bone.
When the cruciate ligament snaps things go wrong. When the dog walks and puts their weight on the damaged knee, force travels down the thigh bone, but the CCL is no longer there, anchoring the thigh and shin bones and stopping them sliding. When the dog's weight is transferred to the shin bone (which is sloping) the thigh bone then rolls down the slope. The result is the shin bone juts forward, gives way, and causes mechanical lameness.
For those struggling with this concept, think of stacking two apples one on top of the other. Press down on the top apple at its core, and nothing much happens. But press the top apple at the side where you take a bite and the bottom apple skids away from underneath it.
With the knee unstable, constant slipping and rubbing creates inflammation and pain. Plus, the leg no longer supports the dog's weight, and so the four-legger limps.
A dog with a ruptured cruciate is lame on the back leg, this much is obvious. But importantly, inflammation inside the unstable knee encourages early arthritis. If nothing is done the dog is likely to develop significant arthritis months or years down the line.
There are lots of factors that determine how bad the arthritis may be. A big one is the dog's weight, with dogs over 20lb body weight at greater risk of severe arthritis - hence why surgery is so important for these guys. Another factor is the steepness of the natural slope at the top of the shin bone. If this angle is shallow, the scar tissue may form which in time stabilizes the knee (this works better for small than their larger canine cousins.)
Long story short, if nothing is done there's a distinct risk of arthritis in the knee.
Cruciate rupture causes a hindleg lameness. Of course, not every limping dog has a damaged cruciate, problems such as hip dysplasia, strains, and sprains can cause hindleg lameness.
The cruciate ligament may fray over time, but it's often a single, sudden event that snaps it completely. The typical story is of a dog that chases a squirrel, yelps, and limps home on a sore back leg.
However, not all dogs are 100% lame with a CCL injury, some are only slightly lame or have problems such as getting up on a slippery floor. If in doubt, always get the dog checked by a vet.
TPLO is a surgical procedure. In essence, it turns the slope (at the top of the tibia) into a flat surface. Think of this like walking downhill on ice on a steep hill (your feet slide out from underneath ) compared to walking on a flat surface. For the damaged knee, this means the dog's weight hits a flat surface (the newly levelled shin bone) and the force travels downward without causing the shin bone to slip forward and give way.
The procedure itself means cutting the shin bone (the 'osteotomy' part of the TPLO) and repositioning the top part so it sits flat, rather than on a slope. The bone is then held in the new position with screws and plates.
If the ligament is damaged, why not just replace it?
Actually, there are lots of different procedures for CCL rupture, some of which do include replacing the ligament. However, these surgeries work best in small dogs, not larger ones. This is because any implant used as a new cruciate ligament can never be as strong as the one created by Mother Nature. Therefore, there's a risk of the implant snapping and the dog being back to square one.
For larger, heavier dogs TPLO surgery is a permanent fix that works well.
It's natural for any caring owner to be concerned about putting their dog through major surgery. So what are the benefits vs risks, and how long does tibial plateau leveling osteotomy recovery take?
Considering this is major surgery, most dogs get back on their paws surprisingly quickly. For example, they often start putting weight on the leg as soon as two days after surgery. Some patients stay in the hospital for a couple of days, so their pain can be managed. Once the dog goes home, it's important they are rested since being too active could dislodge one of the supporting screws. Any skin sutures are removed around 10 days after surgery.
Tibial plateau leveling osteotomy recovery is staged over several weeks. It starts with total rest and the patient being confined to a crate or small room, for around two weeks. After this period they have short lead walks round the yard, and if all goes well at their 6 - 8 week check, things step things up a little. This can include activities such as longer lead walks, hydrotherapy, and physiotherapy.
TPLO is not the only option, but it is a good one. In addition to the TPLO procedure there are other specialist procedures, which may be more appropriate for certain individuals. For small, lighter dogs other surgeries are also possible, each with its pros and cons.
TPLO recovery depends on the dog resting and their owner following the surgeon's instructions. In addition, the patient needs a state-of-healing x-ray approximately six weeks after the surgery. This is to assess if the bone has healed and that the implant is stable.
Then a period follows where the dog is reintroduced to exercise and their muscles built-up. The good news being that TPLO recovery is uneventful for most dogs and the final result is a leg that's good as new.