Max's "Drawer Motion"

Little Max is a lucky dog. He and his buddy, Ewoki, get to go on walks and to the dog park all the time with their human and have a wonderful time doing that. This weekend, though, he over did it and came up lame on a hind leg-ouch! He was holding his leg up, not wanting to put any weight on it at all yesterday. He is a bit better today, touching his toes to the ground, but you can see that he is off his game a bit and so his owner brought him in to see us.

Do you remember reading about Charlie and his hind leg lameness on New Year's Eve? I said that when dogs are lame in the hind end, there are numerous things that could be wrong-anything from a thorn in the paw (wouldn't it be nice if they all were that simple?) to hip dysplasia (an inherited condition where the hip joint never formed correctly, resulting in a progressive, painful degenerative condition.) But there is one problem that is so common that we tend to say all hind leg lame dogs have this until proven otherwise. The problem is called ACL or CCL rupture-anterior (or cranial) cruciate ligament rupture or tear.

The ACL's "job" is to connect the top bone (femur) and bottom bone (tiba) and to stabilize the motion of the joint, keeping it from moving in abnormal ways. We know a knee joint should flex back and forth, but if the ligament is injured, the joint may have what we call "drawer" motion; the lower tibia will move forward as if you are pulling a drawer out of a desk or dresser. Drawer motion is abnormal and when it is present during an exam (done under sedation or anesthesia due to the pain of manipulation and because the strong muscles of the leg will hold the joint together in an awake animal) confirms the diagnosis of ACL rupture. Max had definite drawer motion in his affected stifle and no abnormal motion at all in his good leg. We then took radiographs during his sedation so we could see if there was any other problem like fractures or even neoplasia (cancer) that would affect the outcome of repair and recovery.

Once damage to the ACL was confirmed, we had to talk about repair-that meant surgery. For bigger dogs like Charlie, a trip to the surgery specialist is warranted to have a procedure called a TPLO or tibial plateau leveling osteotomy (see why we call it a TPLO?) Max only weighs about 13 pounds, so he could be a candidate for a different surgery, one we do at our hospital routinely, called a lateral imbrication procedure. In this surgery, heavy suture material, almost like fishing line, is laced along the side or sides of the stifle joint and mimics the function of the cruciate ligaments, stabilizing the motion of the joint. There should be no drawer motion remaining after these lateral imbrication sutures are placed. It is a good procedure, costs significantly less than a TPLO, and should have Max back to good weight bearing in a month or so.

We did get some x-rays of Max's stifle and saw a little piece of bone in the center of the joint. This is common in ACL ruptures as bone can come off from the point of attachment of the ligament and the joint surface. The radiologist will review the films, but the diagnosis is clear.

Max and his owner will go visit the veterinary surgery specialist for a consultation and get their recommendation for the repair of his injury. At his age (10 years) this is less likly to be a conformational issue and more a primary injury-I doubt he will have his opposite leg affected but since he is putting almost all his weight on that opposite leg, it is vulnerable to that possibility. He will be rested and put on anti-inflammatory and pain relief medications before and after his surgery. I said at the start that he is a lucky dog and I really believe that. He has a wonderful owner who is willing to take care of him, he has a good buddy, Ewoki, who watches out for him. And he has a great personality, seeming to realize that his veterinary team is trying to help him feel better-it sure makes us love our jobs all the more and want us to go out of our way to do what he and his owner need. In this case it means closing that "drawer."

Peace,
DrReneigh

Happy New Year!

Charlie started limping on his left hind leg about two months ago. Then he got better. Then he chased after a cat and the lameness returned. It seemed to get better with rest, so his owner wasn't too worried. And then yesterday he started limping again-what a bummer! Charlie's owner now realized her big guy would need some help with this problem.

When I see a dog with a hind limb lameness, especially in a large breed dog like Charlie, I expect the lameness to be in the stifle (knee) until proven otherwise. Literally 80% of these limping dogs have injured a structure in their stifles called a cranial cruciate ligament, and if it is an intermittent or on-again, off-again lameness as Charlie was showing, that percentage is even higher. Initially, the injury causes pain and thus the first signs of lameness are seen. Then when swelling occurs because of the trauma to the tissues and subsequent inflammation, the joint becomes tight and falsely stabilized, resulting in a more normal gait. With rest and/or anti-inflammatory medication, swelling can be reduced and the joint becomes "loose" again, there is bone to bone contact with arthritis developing quickly and, you guessed it, the lameness returns. It is a very predictable pattern and helps us diagnose this very common condition.

The stifle has some pretty complex anatomy. The cruciate ligaments (there are two of them, the cranial and caudal) cross each other in the center of the joint, keeping the joint from moving in an abnormal way. The cranial cruciate prevents the lower bone, the tibia, from moving forward out from under the upper bone called the femur. The action that damages this ligament most commonly is jumping and landing on it while simultaneously twisting to turn in another direction. My own dog, Verbal, ruptured her cruciate ligaments when she was playing frisbee. Trauma certainly plays a part in this condition, but many of the dogs affected are genetically predisposed due to their conformation-it is usually the dogs that are "upright" in their stifles that are prone to this injury. Their legs look straighter rather than angled when you look at them from the side.

Charlie is a pretty big dog (he is a Golden Retriever) with powerful muscles in his hind legs. Because of this, we needed to sedate him to manipulate his stifle to confirm the diagnosis as well as to take some radiographs of the affected limb. We gave him an injection that combined the sedative with a good pain reliever-this resulted in us being able to do a much more thorough and complete exam. Starting at the toenails (you bet that a broken toenail could cause enough pain to cause limping) and moving on up the limb, we found that Charlie had a chunk of something stuck in the hair between his foot pads. We clipped it out-there wasn't any sore adjacent to this "stuff" so I doubted this was the source of his pain. When I am palpating limbs for sources of pain, I usually compare the lame leg to the opposite normal leg. Charlie's left stifle was noticeably bigger than his right one, and there was some heat and swelling associated with the joint. It was also positive for the "drawer sign"-a test of abnormal motion that is present when cruciate ligaments are no longer stabilizing the joint. There is a graphic of this on the Veterinary Partner website to get a better idea:

Drawer Sign

Charlie's hips seemed fine. We took some radiographs to be sure there weren't any other problems in the stifle, (arthritis can develop quickly in these unstable joints) as well as a view of the hips to rule out hip dysplasia as another cause of pain. The radiologist will review Charlie's films, but they look pretty good to me. We gave Charlie a second injection, a reversal agent to wake him up from the sedative so he could go home right away. The pain relief medication would not be reversed, however-pretty cool, huh? He went home with some oral antiinflammatory and pain relief medications as well as a joint support supplement. We also discussed the importance of starting Charlie on a weight loss diet for his overall joint health as he ages but especially as he recovers from this injury.

Unfortunately, Charlie is facing surgery for repair of his damaged ligaments. His owner found out that rest only got them so far and then the lameness returned-this cycle will continue and will become even worse as degenerative joint disease sets in from the abnormal joint motion. If he were a smaller dog, less than 50 pounds or so, I could repair the stifle with an extracapsular procedure. This tightens up the joint to prevent the drawer motion using very strong suture material placed along the side of the stifle. In these larger dogs, however, a TPLO or Tibial Plateau Leveling Osteotomy is performed. This procedure, utilizing biomechanics of the knee joint, actually alters the angle of the joint, allowing the natural weight-bearing of the dog to stabilize the stifle. As it sounds, a TPLO is a complex, specialized surgery that requires special training and equipment. It is usually done by board certified veterinary surgeons and can be fairly expensive.

Charlie will be looking at rest and rehabilitation for a good 6 to 8 weeks after surgery. He really shouldn't be allowed to run or jump or even climb stairs at first. Passive range of motion exercises may help, and if there is an underwater treadmill available, that would be the best exercise of all to help build up muscles without stressing the joint or the osteotomy repair site. And then there is the very real possibility that he will have to go through all of this all over again if he ruptures the ligaments in the opposite leg.

Happy New Year everyone. We are closing the hospital early today so the staff can get started on their New Years' celebrations. I've enjoyed starting to blog this year and hope to continue it in 2009. Be sure to let me know if you have any topics you would like me to write about-I want to keep this fresh and interesting but need your help to do that!

Peace and Love,
DrReneigh