Pelvic Limb Issues

July 8th, 2014 by Dr. Kristyn Richardson


The ankle bone’s connected to the knee bone, the knee bone’s connected to the hip bone….I always thought that song was funny, but as I went through vet school, I came to appreciate its simplicity. We often think of limbs as bones with “stuff “ around it to support it. The most amazing part is that “stuff” is what shapes how a pet moves and functions. Bones are the framework: muscles, tendons, ligaments, fascia, joint capsules, and cartilage are the initiators (with a little help from the nervous system). When we look at all of the problems that can occur with the rear limbs, a significant portion of them can be attributed to problems with the soft tissues or problems resulting from malfunctions of these tissues.

For example, our favorite–the cranial cruciate ligament. Like the human ACL, it is one of the most common ligaments injured in pets. We have seen chronic degeneration that is congenital, but most often there is chronic tearing of the ligament over time due to excessive and repetitive wear. When the CCL tears or ruptures, there is significant lameness, and changes begin within the knee joint that lead to arthritis.

Another example is patellar luxation or knee caps that “pop.” This has typically been seen in smaller dogs in the past, but has been noted more often recently in larger dogs. There are many reasons why this can happen: the groove that the patella tracks in is not deep enough, the femur is bowed to a particular degree, or there is asymmetry to the quadriceps muscle mass or inappropriate timing of the muscles causing the patella to be pulled in one direction or the other. This problem can lead to inappropriate ambulation, limping, inflammation and arthritic change in the knee.

This brings about the question of why these things are happening and why are we seeing more and more of these problems occurring in our pets?

The next few ideas are purely speculation and there is no significant scientific evidence to speak of, but in my years of practice and experience, I think they are worth exploring.

Like human babies, puppies have to learn how to walk. They have to develop muscles and a gait like any child. What if they learn a gait the inappropriate way? What if they do not develop muscle like they should due to lack of exercise or too much exercise? Who teaches them how to walk? These are interesting, unanswered questions with a huge amount of possibility. Since muscles and bones remodel and respond to what the body is “taught,” how do we think this might affect them as their life progresses? I am not discounting the notion that some dogs are born with congenital problems, but if identified early or if we are proactive in our treatment, it’s exciting to think what changes are possible and we do know that we have made positive contributions to these changes with rehabilitation.

Just some things to chew on. What do you think?

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