The dog knee is poorly designed, with its weakest link being the anterior cruciate ligament (ACL). The ACL is made up of two thick fibrous bundles wrapped around one another. This ligament runs from the back of the femur (upper leg bone) to the front of the tibia (the lower leg bone). When a dog is bearing weight on the leg, the ACL keeps the two bones lined up on top of each other just right. When the ACL is torn, the bones slide, causing instability, pain, and often tearing of cartilage.
Little dogs (Toy Poodles, Shih Tzus, Yorkies, and the like) with torn ACLs often will get better just with rest and time. Big dogs, however, won’t. A Lab or a Shepherd, for example, can rest for months, and the first time he jumps off the bed . . . ouch . . . the bones slide and the dog is lame again. Sorry to say, but torn ACLs in big dogs need to be fixed surgically.
At Riverbend we repair four or five torn ACLs a week . . . over 200 per year. Our most common patient is the chubby Retriever, the one who loves eating and chasing tennis balls about equally. Many dogs referred to us have been limping on and off for weeks, even months, before we see them.
How we diagnosis a torn ACL is pretty straight forward. With the dog relaxed and lying on his side with the bad leg up, we push forward against the lower leg bone and backward against the upper leg bone. If the bones slide, we know the ACL is torn; if we get a clicking sound, the cartilage is probably torn as well.
So now on to fixing the knee. There is debate in the dog world as to the best technique to use. Here at Riverbend, we use two different methods — the lateral fabellar suture and the tibial tuberosity advancement (TTA). Both methods have their pros and cons. The lateral suture is less invasive, has fewer complications, and is less expensive. The TTA is more costly but results in a quicker return to function and, in very big dogs, possibly less arthritis down the road. With an experienced surgeon, either technique will do the job well.
No matter what technique is used, be prepared for a long rehabilitation period. Most patients aren’t totally healed until at least six months post-surgery.
Complications do occasionally occur. The most common one we see is tearing of the opposite ACL. One out of three dogs that tear an ACL ultimately tears the ACL in the other knee as well. There’s not much you can do about this except keep your dog slender and fit after having the first knee repaired. The other complication we see is the tearing of cartilage during the healing process. If this occurs, then the knee needs to be re-explored and the torn cartilage removed.
All told then, the story of the dog’s ACL is a mixed one. The bad news is that dogs tear their ACLs with discouraging regularity. The good news is that, with surgery, we can get your puppy back to chasing tennis balls, jumping for Frisbees, and hiking pain–free up a mountain or around the block.