Comparing Lessons On Biomechanics And The Realities Of Clinical Experience

Guest Clinical Editor: Bruce Williams, DPM

Although what one learned in podiatric medical school is invaluable in a podiatry career, sometimes podiatrists may encounter a different reality in clinical practice. These expert panelists weigh what they learned in school with their experience and the current research. They also detail which directions future orthotic research should take. Q: What is the current research telling us about how the foot really functions as opposed to what many podiatrists were taught in school? A: Much of the current research focuses on the importance of the midtarsal joint(s) and how they have a significant impact on foot function, according to Bruce Williams, DPM. He adds that recent research efforts also concentrate on the forces/kinetics of foot function. As Dr. Williams explains, although the rearfoot might continue pronating to the end range of motion, the orthotic device may still change pathologic forces. However, Christopher Nester, BSc, PhD, believes the profession puts too much emphasis on the subtalar and midtarsal joints. As he notes, research says the ankle, cuneiform/navicular and metatarsocuneiform/cuboid joints are sites of considerable motion. “The podiatry model needs to include more joints and reflect the fact that they all make equally important contributions to what the foot does,” asserts Dr. Nester. Craig Payne, DPM, says the approach to biomechanics that he took in school 20 years ago was “somewhat dogmatic” but easier to understand. He notes that much more has been revealed in recent years, including research associated with the effects of joint axes variation on foot mechanics. In addition, Dr. Payne notes emerging knowledge on the role of the first metatarsophalangeal joint (MPJ) in rearfoot function and the fact that the windlass mechanism is assuming more importance. He says one cannot dismiss the current conflicting data. Most importantly, Dr. Payne says the profession has learned more about appropriate research methodology with foot orthoses and the understanding of foot mechanics is increasingly being subject to that kind of scrutiny. Q: How might recent research in foot mechanics and/or foot orthoses affect how podiatrists use orthoses to alleviate foot pain? A: Most current research shows that when one puts a foot orthoses in a shoe, patients get better, notes Dr. Payne. Yet he says clinical trials suggest the type of orthotic does not seem to matter. This does not necessarily coincide with what practitioners encounter clinically so Dr. Payne says clinicians and researchers have some questions to ask. For example, does it matter what type of foot orthoses one uses? If it does, in what population does it matter? Dr. Williams notes that some studies are starting to show positive outcomes with foot orthoses in both rheumatologic patients and juvenile patients. While such outcomes may be a given for podiatrists, Dr. Williams says it is good to see positive outcomes research outside of the profession. The research ratifies Dr. Williams’ experience in private practice in treating patients with chronic low back pain and other musculoskeletal pain disorders, which occurred as a result of lower extremity issues. Dr. Nester believes clinical biomechanical research is becoming easier to conduct. He attributes this to technology being faster and easier to use, and podiatrists having a better grasp of the meaning of the data. He says biomechanical data that explains the effects of orthotic prescription or data explaining what the foot and the rest of the limb are doing in individual clinical cases will affect how the profession assesses the biomechanical effects on each patient. Podiatrists are using prefabricated orthotics more these days, according to Dr. Payne. He says they work but not in all cases. Dr. Payne questions whether the profession can use research to determine which prefab devices do not work. Q: What clinical revelations go completely against the grain of what you were taught about foot biomechanics or the use of foot orthoses in podiatry school? A: In school, Dr. Williams says he learned of the existence of forefoot varus and its role as a primary cause of excessive foot pronation. However, he says recent research has actually shown that forefoot varus rarely occurs and one can usually cast it out of the orthotic. As far as rearfoot varus goes, Dr. Williams learned rearfoot varus posting will prevent pronation.

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