Walking the Biomechanical Runway

Depending on the reason for being there, it is not uncommon for part of your visit to the podiatrist to include a gait and biomechanical evaluation. Gait is the way in which someone walks, their swagger. The patient is asked to roll up their pants and walk back and forth, sometimes fast and sometimes slow. The doctor meanwhile intently watches until satisfied and has seen enough. The doc will then proceed to examine you from your hips to your toes, pulling, twisting and prodding on the way down.  During this ritual the doctor is obtaining information to formulate the treatment plan.  The cool thing about a biomechanical approach to the body’s problems is that the goal is to fix the underlying cause of the problem in a completely non-invasive way. Below are a few big concepts involved in a basic biomechanical evaluation.

Bill Cosby's gait evaluation.

1.       Supination and Pronation: These are probably terms that you are somewhat familiar with but let’s just make sure that we are on the same page. Supination is when the bottom of the foot is moving to face the midline of the body also causing the ankle joint to extend and the foot to turn inwards. Correct terms for these movements are inversion, plantarflexion and adduction. Pronation, the opposite of supination, refers to moving the bottom of the foot to face away from the midline of the body, causing the ankle to flex and the foot to turn outwards. Correct terms for these movements are eversion, dorsiflexion and abduction. The ability of the foot to supinate and pronate in necessary in the function of the foot during walking and running. These terms are also used to describe the foot's position while standing.

Figure borrowed from www.orthoticshop.com. 

2.       Asymmetries:  For the most part, the body was designed to be symmetrical, in movement and structure. Asymmetries lead to inefficient movements that put increased amounts of stress on the body’s structures often leading to breakdown, causing pain.

3.       Limited Joint Range of Motion:  Every time a joint comes to its end range of motion the soft tissue is potentially being stretched beyond the point at which it is capable of recoiling.  Abnormal end range of motion also can mean that you are having non-anatomical bone on transferred energy and motion that is not dissipated by the proper joint. Simply put, the jarring of joints is bad.

4.       Pronation Affects the Entire Body: Pronation, the lowering of the foot’s arch, causes the tibia to internally rotate and is a mechanism that the body uses to shorten an elongated limb. Try it. Stand up and try to pronate your foot while standing. The only way that you can do it is by internally rotating your leg forcing you into a knock-kneed type stance. This internal rotation translates up the leg all the way to the hip leading to tilting of the pelvis. This tilting affects the spine and up to the shoulders. This path of misalignment has been shown to cause a whole host of problems, including but not limited to: patellofemoral pain syndrome, iliotibial band friction syndrome, ACL injuries, sciatic pain, and lower back pain. Pronation also decreases the amount of upward bend (dorsiflexion) in the big toe which over time can lead to bunions and osteoarthritis. 

The Vitruvian Man, 1485. Leonardo da Vinci

Often times only parts of the exam will be conducted depending on the problem and each doctor has small differences in the way in which the information is obtained. Treatment recommendations to improve the biomechanics of the foot include strengthening specific muscles/muscle groups, orthotics and shoe types.