By far the most common cause of lameness I see in the hind legs of large dogs is due to torn anterior cruciate ligament (ACL).
The cruciate ligaments are two bands of fibrous tissue that sit deep in the knee to hold the femur to the tibia and allow it to articulate properly. In dogs the most common one to rupture is the ACL which runs from the back of the femur to the front of the tibia within the knee joint.
Obesity, as well as chronic inflammation due to arthritis, can predispose this ligament to tearing. Also, trauma from running and jumping and twisting can cause the ligament to tear.
Typically we hear of active dogs running and suddenly they may yelp and then refuse to use their hind leg as the ligament has torn.
Some dogs may only have a partially torn ligament, which causes a mild lameness that comes and goes for a long time and often results in a full tear at some point.
To confirm if a dog has torn its ACL, we often rely on a couple of tests such as a cranial drawer test or a tibial thrust test.
The dog may need to be sedated to be completely relaxed for this test and then we are able to determine if there is looseness of laxity within the joint. X-rays are also useful to assess the degree of degenerative change and joint swelling.
Often, dogs with ACL damage will sit with the affected leg held outward and with time they develop a bump on the inside of the knee referred to as a medial buttress. This happens as a result of the femur pinching on the meniscus as it slides to the back portion of the joint.
Meniscal damage is quite common and will cause the dog to be more lame and sometimes have a click to the knee.
Generally some form of surgery is required to repair torn ACL ligaments.
Without surgery the dogs develop chronic arthritis and will be lame for a long time and have permanent damage.
Over the years there have been many different types of surgical procedures to treat torn ACLs. One of the most common traditional procedures is the lateral stabilization technique, which involves placing two heavy nylon bands from the femur to the tibia just outside of the joint.
While I have performed several hundred of these through the years, and dogs have done well with this technique, there are newer procedures that show even better results and provide a more bio-mechanically normal joint.
In the 1990s a vet from Oregon developed a procedure called the TPLO. This involves cutting the tibia and rotating the top end of it several degrees and plating it back on.
It is quite invasive and recovery is still two to four months.
Although it does work well and is preferred by some specialists it is not a perfect procedure. In recent years a newer technique called the TTA has been developed by researchers in Switzerland.
It provides the same bio-mechanical change by simply advancing the front of the tibia and placing a titanium plate to hold the new position.
With more than 100,000 of these performed worldwide, the results have been the most impressive.
I have performed a number of TPLOs and also several TTA procedures, and I would have to say I am most impressed by the rapid recovery of dogs with the TTA.
They are often walking without lameness in four weeks.
If you would like to learn more about these procedures, feel free to give me a call. It is a big investment in your dog’s knee and you want to make sure you have the best outcome so they can get back to running and enjoying life.