Zoey, my four and a half year old Pembroke Welsh corgi, was out running in the yard a week ago. As a member of the herding breed, she has an overabundance of energy that she needs to burn off regularly; this is usually accomplished by running full-tilt in circles in my backyard. After her latest sprinting episode, she came inside and refused to bear weight on her right hindlimb. I could tell by palpating her leg that her knee (stifle) was the main source of her pain, and her muscles were so tense she would not let me manipulate it. As is the case with most veterinarians, the knowledge that we have is dangerous with our own animals, and I immediately jumped to the worst case scenario of a torn ACL, not something simple like a muscle strain. I withheld breakfast from her Monday morning, and brought her in to have Dr. McGee examine her knee. She showed no improvement overnight, and the next day he confirmed what I thought, that she had ruptured her ACL. And so our story begins…
A ruptured cruciate ligament is the most common knee injury of dogs. The typical presentation of the injury is an active healthy dog that suddenly becomes completely non-weight bearing on a hindlimb and is very painful. Mild improvement will be seen if left untreated after the first one to two weeks, but the animal will never bear 100% of normal weight and arthritis will begin to form relatively quickly.
The knee is a fairly complicated joint. It consists of the femur, the tibia, the kneecap (patella), and the bean-like fabellae. Pieces of cartilage called the medial and lateral menisci serve the function of a cushion in the join, fitting between the femur and tibia. An variety of ligaments holds everything together, allowing the knee to bend the way it is supposed to and also to keep it from bending a way it shouldn’t.
There are two cruciate ligaments that cross inside the knee joint: the anterior cruciate and the posterior cruciate. Their names are derived from the side of the knee (front or back) where their lower attachment is made. The anterior cruciate ligament prevents the tibia from slipping forward from under the femur.
Over the following weeks, I will post a series of blogs following Zoey through her diagnosis, repair, and rehabilitation for her knee injury. This is a very common injury we see here at Mt. Carmel, and it is also something that tends to be an overwhelming diagnosis. Feel free to follow along as we track her progress over the next month!
~Dr. Mara Schultz