By Mark Mendeszoon, DPM
As a podiatrist, athlete, coach, and independent running shoe proprietor, I have always had an interest in biomechanics and the impact on lower extremity overuse injuries and conditions. Perhaps the most well-known biomechanical term, pronation, is also the most misunderstood. In his recent article, Benno Nigg et al. (see Foot Pronation, pg 33-38)1 confirm that pronation is an integral part of the gait cycle and has a direct impact on lower extremity injuries. After a thorough review of previous studies, Nigg confirmed that pronation is appreciated by the profession but still a theory and not an absolute science. While that may be true academically for clinicians, the importance of recognizing biomechanics is imperative in treating patients. It can also play a role in building one’s practice.
In the second year of podiatric medical school, podiatrists are principally trained with Root’s Foot Morphology Theory as the foundation of biomechanics. This theory emphasizes the integral relationship between the subtalar and midtarsal joints’ anatomy and mechanics. Over the last several decades, however, Root’s theory has been challenged and proven to have inconsistencies due to the fact that pronation is still a misunderstood motion. What is certain is that pronation is a three-plane motion affecting both the subtalar and midtarsal joints and eversion of the subtalar joint is the primary motion of pronation in the frontal plane. Many times eversion is misconstrued as pronation. As a result, more recent theories, such as Kirby’s Tissue Stress Theory and Dananberg’s Sagittal Plane Facilitation Theory, have evolved and been more accepted by the profession. The astute practitioner will combine all three theories to assess and treat their patients.
The importance of applying biomechanics into your clinical practice is crucial. Regardless of any foot and ankle condition, a thorough biomechanics exam must be implemented to provide the best outcome for your patient. A complete head to toe exam should only take a few minutes by the skilled practitioner and thus provide many answers to help solve the problem at hand.
Initially, the practitioner would have the patient evaluated by performing an open kinetic chain examination by sitting and lying down. In this portion of the exam the practitioner is evaluating joint mobility, range of motion, integrity of ligaments and soft tissues, joint range of motion, symmetry of contralateral sides, muscle strength, leg length, and painful areas. If the patient is able to stand and ambulate, then a closed kinetic chain exam is performed. In closed chain pronation, the tibia internally rotates, the talus plantarflexes and inverts, and the calcaneus everts. Evaluation of posture, spine position, hips, pelvic tilt, knee position, and gait pattern is noted. Lastly, evaluation of shoe gear and any foot orthoses or braces should be noted. Performing a thorough history and physical examination and reviewing diagnostic testing should allow the practitioner to establish a working diagnosis and create a treatment protocol.
Whether the patient needs conservative or surgical treatment, the fundamentals of biomechanics should be respected so that the patient may have optimal healing potential. Once the pathomechanics of the condition are established and properly diagnosed, implementation of treatment is the rewarding part since we all know how valuable the need for ambulation and mobility are for the patient. The integration of human biomechanical concepts with human kinesiology, anatomy, physiology, surgical procedures, biomaterials, foundation of orthoses, shoe anatomy, and function and rehabilitation make our profession one of the most dynamic fields in medicine. Despite all the advancements of podiatry in the last few decades, the tenets of biomechanics are at the cornerstone of our success and should be valued and implemented as a fundamental component of patient care.
Mark Mendeszoon is a senior partner at Precision Orthopaedic Specialties Inc. located in Chardon, Ohio. He is the director of University Hospitals Richmond Heights Medical Center Advanced Foot & Ankle Surgery. In addition, he is the owner of three Achilles Running Shops in Northeast Ohio and Erie, Pa., as well as President of the Maple Leaf Track Club.
- Nigg B, Behling AV, Hammill J. Foot pronation. Footwear Science. 2019:11:3;131-134.