Q: Dr. Habermann, our dog was recently diagnosed with an injured cruciate ligament and it was recommended that it be surgically repaired. What are your recommendations on this?
A: Torn/ruptured/injured cranial cruciate ligaments (or ACLs if we were talking about the human condition) are very common in veterinary medicine. It's primarily a dog problem, but we do see it occasionally in cats—generally in grossly overweight felines—and doesn't seem to occur only in larger dogs. I've seen it in chihuahuas all the way up to large mastiffs and Great Danes.
The injury isn't always associated with trauma either. There is a philosophy (to which I subscribe) that many torn cruciates develop when the ligament slowly wears away. Some slight twist of the leg, bend in the knee, etc., causes the ligament to finally “break.”
The diagnosis isn't that difficult. If a pet presents with a lameness of the hind leg—often discernible by the way they're carrying the leg—and the discomfort is in the stifle (technical word for knee), we sedate and X-ray. Sedation relaxes the pet, allowing us to confirm the ligament is, in fact, at fault. By manipulating the relaxed joints in such a way, if we get a particular movement of the joint, known as a drawer sign, we can confirm a cruciate injury. The X-rays show if there's any other abnormalities of the joint as well as general conformation of the knee in question; sometimes other orthopedic problems can be inevitable depending on the shape of the dog's joint.
Ideally, once diagnosed, the pets should have surgical repair of the problem. There are a number of repair options available. At Foothills Veterinary Clinic, we offer a modified Paatsama technique. Basically, we open the joint, clean out the damaged ligament and any other damaged tissues (most of these dogs generally have a torn meniscus as well) and replace the broken ligament with a muscle graft we take from the thigh muscle. For decades this was the surgery of choice to repair these knees, but some time ago a new technique was developed known as the TPLO repair (tibial plateau leveling osteotomy). While earlier versions of this surgery had increased complications, specialists who perform the procedure have perfected it to a point where it is considered the gold standard of repair for these ligaments. The TPLO fix tends to be a bit sturdier with less post-op arthritis than the older Paatsama technique we are still doing. Our procedure requires a two-week, restricted activity recovery, while the TPLO procedure has a six- to eight-week recovery because it involves bone screws and metal plates which prolong healing. Typically, dogs that have successful surgeries (regardless of which one) return to almost completely normal function several months post-op.
For older dogs, dogs with underlying problems that prevent them from having general anesthesia, or for owners that have financial restraints preventing them from having surgery done on their pet, we will usually recommend a combination of nonsteroidal anti-inflammatory drugs and pain medications in conjunction with exercise restriction for several months. In many of these patients, the joint capsule (the tissue around the joint that provides support and keeps the joint fluid in close contact with the joint) will thicken over time, providing some support that is no longer present due to the cruciate being damaged.
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