Biomechanics of the Lower Extremity

As I lay here in bed thinking about the intricacies of lower extremity biomechanics and not sleeping, I have started formulating a three-dimensional model in my mind in regards the movement patterns. Similar to organic chemistry where you must construct a molecule in your mind and move it around, biomechanics is really just a macro-version of organic chemistry models. Some people really excel at this, where others, like me, have to work at it.

I find the biomechanics course we are in to be quite fascinating. Linking movement from distal to proximal is incredibly complicated. For instance, we learned the normal movement of the foot during the gait cycle a few weeks ago and now we've ventured into abnormal foot, knee and hip biomechanics. If, for instance, the femoral head grows too anteriorly, it will cause an internal rotation of the distal femur near the knee and a compensatory external rotation of the tibia and even excessive pronation of the foot. If the femoral head grows too posteriorly, it can cause genu varum at the knee which is essentially "bull-leggedness". Genu varus of the knee could lead to rear foot varus and potentially over supination or pronation depending on how the foot compensates.

Now if you take these abnormal biomechanics a step further and talk about functional issues versus congenital, it gets even more interesting. Functionally, you can have an anteverted femur or a valgus knee or even a excessively pronated foot which can be corrected. Congenital issues can be corrected with posting up short legs or correcting for a malformed foot bone. The trick in learning this stuff is to know when the issue is functional or not. I am not there yet with my understanding of it all but I know I will be there soon.

What I find most interesting is how the muscles are involved in faulty movement patterns. Connecting the structure and function of muscles is very hard to do. There are so many muscular actions and details to human movement beyond bones gliding on one another that it can get overwhelming. For instance, when we were studying the foot, there was something mentioned about the lower leg muscles forming a sling which supports the arch. The tendon of the fibularis longus wraps behind the lateral malleolus and attaches to the plantar surface of the foot just proximal to the first ray (big toe). And the tibialis anterior muscle attaches to the dorsum of the foot, practically on the other side of the attachment for the fibularis longus. This apparently forms a harness or sling that dynamically supports the foot during movement. If one muscle involved in this harness becomes weak or too strong, it can cause a functional abnormality and become a pain producer. And if the issue persists for years where the person copes with the pain, osteophytes can grow producing bone spurs and arthritis.

It is fun to start wrapping the mind around these concepts in a clinical way. For the past year and a half we've learned what "normal" is through taking tons of basic science classes and now we are getting a good dose of "abnormal". Combine this with the orthopedic and neurological tests we are learning and eventually we'll be able to diagnose the problem and fix it. The knowledge we are gaining is so versatile and applicable to everyday life. We all get pain from physical activity or the lack of it. Sometimes the pain dissipates over time and the problem fades away but other times the issue becomes more chronic and abnormal movement patterns become "normal" to the brain. We, as modern chiropractors, are suited not only to fix the problem but to re-educate the kinetic chain to work as it should.

When thinking about the future, I will be doing a lot of physical therapy in my office. At least, this is my thought right now. My reasoning is that if you look at the amount of time people spend sitting, it is much greater than the time spent working out or countering the effects of sitting. My hope is to have a therapy focus that continues care into physical fitness services. Hire some trainers and essentially feed them clients through extending their care in the office. I see this as a win-win situation for both the patient's health and my bottom line.

It isn't unethical in my mind to advocate healthy living beyond adjusting everyone in hopes the natural forces take over and bring good health. Unfortunately, there are some who believe bone's out of place impinge nerve flow and if they are "freed" up then health will follow. This is stupid and should be disenfranchised in the profession. Health is a biopsychosocial phenomenon and is much more complicated than a bone out of place pinching a nerve. This could turn into a tangent so I am going to end by wishing good luck to those who must struggle through another difficult test tomorrow.

All for now