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Two weeks down, one to go for the remainder of my orthopedic surgery block and my oh my has it flown by quickly. A fellow classmate of mine pointed out to me how my class is already 1/4 of the way through our final year, which I find amazing since every morning it feels to me like we've all just begun. This past week was a bit less hectic for me since I've started getting a hang of all the nuts and bolts of the inner-workings of the teaching hospital, but I was still super-busy nonetheless. Thankfully, of all the appointments I saw this week, only two stayed for surgery; i.e. the rest were outpatient visits (rechecks, hip evaluations, etc). The two that stayed at the hospital both had the same problem and received the same surgery: ruptured cranial cruciate ligament.
In people, this is known as tearing one's ACL, which stands for "anterior cruciate ligament". These are the same thing, except the first word refers to a direction. The semantics are different between animals and people because of how we are biped and animals are quadriped. Anterior in people means in the direction of the front of your body, and cranial in animals means towards the head. That aside, there are two cruciate ligaments and they are both inside of your knee joint. They have a number of vital purposes: preventing your knee from over-extending (yeah...ouch), preventing your knee from twisting, and preventing what's called the "cranial drawer". This is where the femur (your thigh bone) slides backwards off your tibia (your calf bone). There is a cranial and caudal cruciate ligament, but the cranial one is what tears most often because it receives more stress than the caudal one (caudal meaning towards the back end of the body). Initially, the tearing of the ligament hurts like hell, but the pain quickly goes away. However, in the long run, this ends up being catastrophic because osteoarthritis and degenerative joint disease develop within the joint to a severe degree because of abnormal loading of weight on the joint.
There are a number of ways of treating this problem, but unfortunately surgery is really the only way to go. The degenerative joint changes will be inevitable, but having surgery will greatly help to delay the disease. Both of my patients this week had a procedure called a "Tibial Plateau Leveling Osteotomy" or TPLO. I won't go into great detail, but I first need to point out a crucial anatomic point about the tibia. The top of it is relatively flat as one would hope, so that the femur and tibia can have two flat smooth surfaces which interact. What happens in the TPLO is that we make a semi-circular cut to the top of the tibia and rotate it backwards so that (when looking from the front of the tibia to the back), the top of the tibia, or plateau, slopes upwards. This, in essence, prevents the femur from sliding off the back of the tibia and causing the drawer I mentioned above. Because we are intentionally fracturing the tibia, we then place a plate on it with some screws to secure it in place. I completely understand if all of this comes off as gibberish to you. To be completely honest, I had the greatest difficulty in understanding what went on with this procedure until I saw it. The best part of all was how the surgeon allowed me to drill and place one of the screws into the plate (under his very close and scrutinizing supervision of course).
While this whole description may come off as horrifying or gross to some, please take into account the patient here. If left alone, the dog (and very rarely cat) will not be able to walk on the affected limb within 6 months to a year, leading to either amputation or euthanasia depending on the client. By doing this barbaric (I supppose) procedure, these dogs will get multiple years of healthy ambulation out of the limb assuming it is diagnosed quickly enough and the dog isn't already ancient. In fact, every one of my patients thus far this block who have received the TPLO are already back to using their affected limb to full function. More often than not, the cruciate rupture occurs to larger breeds of dog, but it can also happen to small/toy breeds as well. In regards to the cause of the rupture, all we know is that the ligament slowly degenerates on a microscopic level for some time, resulting in an overall weakness and increased fragility. Unfortunately, noone knows exactly why this is happens, and both athletic dogs and dogs that are indoor couch-potatoes get it all the time. If you or anyone else you know has a dog that ruptures its cruciate ligament, please keep in mind that 60% of dogs that rupture one, will rupture it in the opposite limb within a year or two.
One last point I'd like to make before logging off is that you shouldn't let this make you frightened or concerned about letting your dog get the exercise it needs or desires. This only happens to a very small fraction of dogs. If anyone would like more details on this process or the procedure, I'll gladly dig up or draw out a picture to help enlighten you. Take care!