Your dog’s Cranial Cruciate Ligament is akin to the ACL in humans, and tearing this ligament is one of the most common knee injuries in dogs.
Cranial Cruciate Ligament (CrCL) Injury & Tibial Plateau Leveling Osteotomy (TPLO) Surgery
In dogs, the Cranial Cruciate Ligament (CrCL) is analogous to a person’s Anterior Cruciate Ligament, also known as the ACL. People are usually familiar with ACL tears in athletes- and just like in people, this ligament tear is the one of the most common knee injuries in dogs.
What does the Cranial Cruciate Ligament do and how does it become injured?
One of the important functions of this ligament in the knee is to prevent forward and backward sliding of the femur on the tibia bone. However, in dogs the CrCL plays a more significant role and is anatomically different than the ACL in people. Unlike humans’ ACL, the CrCL tear is often the result of subtle, slow degeneration that has been taking place within the ligament rather than the result of trauma to an otherwise healthy ligament. This is why approximately half of the dogs that have a cruciate ligament problem in one knee will, at some future time, develop a similar problem in the other knee. Also in contrast to humans, the skeletal structure of the dog knee is such that the CrCL is under a tremendous mechanical stress even during relatively sedentary activities. And the ligament itself, on a size by size basis, is a much thicker ligament in dogs, which unfortunately means that ligament replacement techniques, like the ones frequently performed in humans, are challenging in dogs.
CrCL ruptures happen to all ages and breeds of dogs. Diagnosis is usually straightforward with xrays, palpation and evaluation of gait.
Does my dog need surgery? Isn’t there another treatment option?
Since the CrCL plays such a pivotal role in stabilizing the knees of dogs, there are really no non-surgical options for most patients with a tear. Non-surgical options might include activity restriction, weight loss and anti-inflammatory medications, but this is not a treatment per se, because it does not stabilize the knee. While this regimen may allow the knee joint inflammation to subside somewhat and the symptoms of lameness and pain may decrease with time, changes (arthritis) inside the joint are still occurring. It is important to point out that, in general, the earlier surgical therapies are performed the more effective they are, thus a “wait and see” approach to non-surgical management based only on wishful thinking is seldom advised.
What are the treatment options?
TPLO surgery seeks to stabilize the stifle not with a false ligament, but by re-orientating the slope of the way the femur and tibia interact after the CrCL ligament ruptures. When the crCL tears, the femur slips down the tibial plateau. By making a circular cut in the top of the tibial plateau and ratating the contact surface of this bone until it attains a level orientation, this reorientation of the tibial plateau renders the knee relatively stable and independent of the role of the cranial cruciate ligament. The cut in the bone is stabilized by the use of a bridging bone plate and screws.
A traditional method of CrCL stifle surgery offered is known as Extracapsular Suture Stabilization. In this technique, a false ligament is anchored outside the joint to mimic the angle of stabilization created by an intact CrCL. However, published studies as well as a wealth of anectodoal evidence suggests that this method is vastly inferior to TPLO surgery for active or medium to large breed dogs. In those patients, the false ligament is rarely stable. It may work for some small breed/inactive dogs, but is not recommended for any reasonably active or large dog.
How long before my dog is back to normal after surgery?
TPLO surgeries require special training and equipment and should only be performed by a trained orthopedic surgeon. The outcome of TPLO surgeries with such a surgeon and with good at-home care and restricted activity is generally very good.
The short and medium term aftercare is mostly strict restriction of activity for 8 weeks. The patient is rechecked at 2 weeks, mostly to make sure that this incision is healing well. Most dogs will have some weight bearing strength at that time.
At 6-8 weeks, the surgeon rechecks the patient and an x-ray of the leg is needed to evaluate healing of the osteotomy site. If all looks well then the patient can start rehabilitation techniques as outlined by the surgeon. Generally, most exercise restrictions are lifted at 4 months, and full working activities (agility, hunting, etc) can resume at 6 months.