What Causes a torn ACL ligament in a dog?

The anterior cruciate ligament (ACL) - otherwise known as the cranial cruciate ligament - is a fibrous band of tissue that helps to connect the thigh bone to the lower leg bone. 
Injury to the ACL is pretty common in younger (1-3 years old), larger, active dogs.  There are many factors that contribute to the tearing of the ligament.  Unlike people, where a traumatic event is a major cause, most times a dog's ACL will tear unexpectedly and without an obvious cause.

How Can We Fix It?

There are a few different, common procedures that are done to fix the ACL tear.  We've listed them below, as well as some pros/cons of each, and their relative prices.


TPLO:  The tibial plateau leveling osteotomy surgery has been around for over 20 years.  The idea behind it is to change the angle of the tibia so that the femur above it no longer slips backwards.  The ACL is suppose to prevent this from happening but when it tears, the femur tends to slip backwards from the tibia and this causes pain and inflammation.  This surgery has a very high success rate (~95%) and is our favored procedure in dogs over 30lbs.  The only downside is cost. At our clinic, the total cost is $3,500.

IsoLock CrCL:  Another variant of this surgery is known as the tightrope technique.  This technique has been around for about 5 years.  The idea behind this surgery is to recreate the torn ligament with an artificial one.  The material used is high-strength and is used extensively in human surgeries.  It is resistant to stretching or breaking. The benefit to this surgery is that no bones are cut, so the procedure is less invasive or painful. The downside is a slightly higher infection rate than the TPLO surgery.  The overall cost at our clinic is $3,500

CBLO:  The Cora Based Leveling Osteotomy surgery is the newest way of repairing a torn ACL in the dog.  It has the advantages of both the TPLO, by leveling the tibial plateau, and the TTA, by moving the patellar tendon forward.  This surgery is suited for dogs that are still growing or one’s with excessive tibial slope.  At our clinic, the overall cost of this procedure is $3,500.


TTA:  The tibial tuberosity advancement has been around for over 10 years.  The idea behind this surgery is to move the patellar tendon forward so that the forces acting on the knee cancel out - the backwards slope of the tibia pushing the femur backwards is counteracted by the patellar tendon pulling the femur forwards.  The tendon is moved forward by cutting the place it connects to on the tibia and pushing it forward.  The cut is made in a non-weight bearing area of the bone, and so the recovery tends to be faster and less painful.  Because this surgery is as difficult to perform as the TPLO but has slightly worse results, we currently do not offer this option.

Extracapsular Technique:  Other words for this include lateral fabellar suture, lateral suture stabilization, and "fishing-line technique".  This surgery has been around for about 40 years.  This tends to be one of the more common ways to repair an ACL tear because some general practitioners feel comfortable performing it and it's quicker and less invasive to perform.  In the past, results have been mixed due to flaws in the nylon implant - causing it to stretch or break.  We now use a FiberWire implant that doesn't have these flaws, and so the results have been much better.  This tends to be our recommended surgery in pets under 30lbs.  The total cost at our clinic is $1,800.