Emerging Trends In Research With Orthoses And Biomechanics

   As podiatry continues to emphasize evidenced-based medicine more and more, some of the leaders in biomechanics research share their thoughts on current studies and speculate about how future research with orthoses may eventually alter the way podiatrists practice.

   Q: What orthotic-related research projects have your completed or are you currently in the midst of studying?

   A: Cherri Choate, DPM, is working with Paul Scherer, DPM, and Howard Hillstrom, PhD, and his research group at the Hospital for Special Services in New York City. She says Stride Rite Shoes has formed a research team in an attempt to design the next generation of children’s shoes based on clinical data. The goal of her study is to determine if and how different types of shoe designs impact pediatric gait.

    “Although the study is still in the stage of data collection, the long-term applications could be very important in understanding the development of the foot and its relationship to shoe gear,” says Dr. Choate. “After many years of treating pediatric feet primarily by speculation, the results should help us develop evidence-based protocols for treating pediatric foot pathology with shoes and orthotic devices.”

   Christopher Nester, BSc, PhD, and his group recently finished a two-year project to develop a mass-produced insole (the salfordinsole™) that has the durability and biomechanical performance of a custom-made orthosis. Testing proved the insoles reduced foot pronation, according to Dr. Nester.

   Irene Davis, PhD, PT, has studied the effect of inverted orthotics on rearfoot mechanics during running. Other projects include assessing the effect of orthoses on rearfoot control and shock attenuation during running, and how orthoses affect forefoot and rearfoot strike in runners. She has also investigated the effect of wedged orthoses in patients with knee osteoarthritis (OA).

   Joshua Burns, PhD, B App Sc (Pod) Hons, is involved in designing and evaluating foot orthoses and footwear for the treatment of pain in a variety of conditions including cavus foot, the neuroischemic diabetic foot, rheumatoid arthritis and lower limb injuries in triathlon athletes. He notes having a particular interest in the orthotic management of children and adults with neuromuscular disorders like Charcot-Marie-Tooth disease and Duchenne muscular dystrophy.

   Dr. Burns is also working on the development and validation of clinically relevant outcome measures. He says establishing these measures can help accurately and reliably capture the beneficial effects (e.g. plantar pressure, gait analysis, functional performance) of foot orthoses from a biomechanical perspective.

   Q: What technological advancements do you foresee making an impact in biomechanics research?

   A: Dr. Nester asserts the integration of imaging and motion technologies will provide unique insight into the biomechanical behavior of the foot and ankle. One will be able to track structures in detail during activities and movements, and create patient specific visual and computational models. He says this will provide excellent research tools as well as useful visual aids in clinical practice to help educate patients.

   As Dr. Choate notes, the gold standard for gait analysis in the global research community is the six-camera, three-dimensional motion analysis system. When one uses this system in conjunction with force plates, gait mats and videography, she says physicians can obtain a tremendous amount of data in both clinical and research scenarios. Although relying on static measurement data is of limited value, Dr. Choate says the new systems and dynamic values, including temporal information, should lead to “significant advancements” in the study of lower extremity mechanics.

   In the near future, Dr. Choate says the profession should address the issue of access to technology such as gait labs. As she notes, the high cost and high maintenance of gait labs means there are only a handful of fully functioning motion analysis labs available globally.

    “It is my feeling that these labs should be accessible to the clinicians in their communities,” explains Dr. Choate. “ … I foresee that future physicians will be able to refer patients for motion analysis studies and gain immediate and applicable information to affect patient care.”

   For example, Dr. Choate says the information from force plates may be helpful in treating various pathologies including diabetic foot ulcerations. Clinicians may also be able to obtain information that will help with shoe fit issues, offloading, orthotic problem solving and the linking of foot complaints to abnormal motions in the back, hips and knees, according to Dr. Choate.

    “Reliable, valid and non-invasive techniques of better assessing the foot-to-shoe interface (inside the shoe) will revolutionize our understanding of the nature and mechanism of foot pain, and its response to orthotic therapy,” opines Dr. Burns.

   Dr. Burns says technological advancements will range from clearer electromyography and fluoroscopy to the ultimate in functional magnetic resonance imaging (MRI). Dr. Davis also cites the emergence of imaging modalities such as MRI and dual fluoroscopy. As she notes, certain bony structures (such as the patella, talus and navicular) are not well suited to the placement of external markers. However, new imaging technologies can obviate the use of external markers by permitting the study of bony alignment during movement, which is not possible with current motion capture systems.

   Dr. Burns adds that we will continue to see advances with in-shoe pressure studies, particularly when it comes to measuring shear force. Refined measures of the foot and lower limb in very young children and how to interpret them will help target preventive orthotic therapy, according to Dr. Burns.

   Q: Which areas in lower extremity biomechanics will be the focus of future research?

   A: Dr. Burns notes the importance of pediatric research. He maintains that many areas require a more thorough biomechanical investigation. Dr. Burns says one key priority is the evidenced-based assessment of the growing foot and ankle in children, with particular focus on the predictors of foot pain, disability and deformity.

   Dr. Choate also notes that pediatric patients will be important in future research. She says studies by Mickle, Powell, Selby-Silverstein and Evans are starting to dispel myths about pediatric treatment modalities.1-5 Dr. Choate notes a worldwide awareness of the importance of early detection and the need for treatment algorithms for children. As she points out, early diagnosis and treatment may also lead to improved midlife outcomes for patients with select pathologies.

   In addition, Dr. Burns also advocates comparing the effects of AFOs and foot orthoses on motor function and walking ability in children with neuromuscular disorders.

   In the future, Dr. Davis says research will concentrate on new technologies like imaging and modeling to help understand normal and abnormal biomechanics. She claims that real-time motion analysis can provide more accurate biomechanical feedback to correct faulty biomechanics. Since the population is aging, she notes that preventing and treating OA may receive more emphasis in the literature.

   In regard to her own research, Dr. Davis is currently concentrating on the etiology and treatment for patellofemoral pain syndrome and stress fractures in runners.

   Dr. Nester notes the main focus of his research is detailing the biomechanical purpose of the small structures in the foot. While there is a good knowledge of the function of larger joints and the muscles of the legs and the plantar fascia, Dr. Nester says there is not as much awareness when it comes to the function of lower extremity ligaments, intrinsic muscles, etc.

   To this end, he is undertaking invasive and non-invasive in vivo research. He is also using dynamic cadaver simulations in collaboration with bioengineers in China. Finally, Dr. Nester is using foot modeling, which is in the early stages.

   Dr. Burns also believes the diabetic foot still requires broad investigation, application and innovation from a biomechanical perspective.

   Q: In the past decade, which studies have had the most impact on orthotic intervention in practice?

   A: Drs. Nester and Burns cite a study by Stacoff, et al. Dr. Nester says this study demonstrates the individual response to orthoses and hints at the complex factors that influence how the foot responds.6 “In other words, it is not as simple as Root said it was,” opines Dr. Nester.

   Dr. Nester says a long-term 2002 study by Woodburn, et al., demonstrated that foot orthoses are beneficial for people with rheumatoid arthritis (RA).7 He says this study has led to a demonstrable impact on podiatry practice in the United Kingdom.

   Dr. Burns says the Woodburn study and another study by Landorf, et al., are “standout” randomized controlled trials in evaluating the effects of custom orthoses on different types of pain.7,8

   Dr. Davis concurs about the usefulness of Landorf’s study, which found that a prefabricated orthosis was as effective as a custom device for plantar fasciitis. The study suggests that one may use a prefab device as a first treatment, which Dr. Davis says could reduce costs for patients and increase their access to treatment.8

   Dr. Nester also cites a 2003 study by Woodburn, et al., saying it ties biomechanical data to clinical observations in demonstrating that orthoses have long-term biomechanical effects when patients with RA use them continuously.9 Dr. Choate notes that the Woodburn study focused on the relationship of the subtalar joint (STJ) and ankle joint in patients with RA, using rigid orthoses in a patient group that physicians usually address with soft orthoses. She notes an important finding was that the rigid orthotic initially maintained and then improved the reduction in cumulative STJ eversion motion.

   The value of Woodburn’s study is not just the end data but also “the ultimate adjustment of podiatry’s established paradigm of treatment of patients with rheumatoid arthritis,” claims Dr. Choate. Dr. Nester calls that study “a good example of biomechanical data informing practice rather than being collected simply for its own sake.”9

   Dr. Choate also mentions the studies of Burns’ Australian group, particularly the group’s study of pes cavus.10 She maintains that study is “just beginning to scratch the surface” on establishing normal and abnormal facets of gait for patients with pes cavus, a condition that can be neglected. Burns’ results have shown that pes cavus has a unique gait pattern that is independent of etiology and that may be significantly influenced by rearfoot pain, according to Dr. Choate.

   In addition, Dr. Choate cites Selby-Silverstein’s study, which found that semi-rigid custom orthotics significantly improved pain, speed of ambulation and quality of life in patients in a physical therapy group.5 As she notes, the key of this study was the emphasis on quality of life issues.

    “With the increasing number of studies focused on the pediatric and geriatric populations, it is imperative that we evaluate the quality of life issues, including emotional, social and physical functioning,” explains Dr. Choate.

   The research of Redmond, et al., is effective in showing the mechanism of action for orthoses on plantar pressure and gait, points out Dr. Burns.11 He also references two “very exciting” studies of biomechanics by Nester and Sheehan.12,13

Dr. Burns is a National Health and Medical Research Council (NHMRC) Australian Clinical Research Fellow at the Institute for Neuromuscular Research at The Children’s Hospital at Westmead in Australia. He is also a Conjoint Senior Lecturer in the Discipline of Paediatrics and Child Health, Faculty of Medicine at the University of Sydney in Australia.

Dr. Choate is an Assistant Professor in the Department of Applied Biomechanics at the California School of Podiatric Medicine at Samuel Merritt University.
Dr. Davis is a Director of Research at Drayer Physical Therapy Institute. She is a Professor in the Department of Physical Therapy at the University of Delaware. Dr. Davis is a Fellow of the American College of Sports Medicine.

Dr. Nester is the Director of the Centre for Rehabilitation and Human Performance Research at the University of Salford in the United Kingdom.

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References:

1. Mickle KJ, Steele JR, Munro BJ. Does excess mass affect plantar pressure in young children? Int J Pediatr Obes 1(3):83-8, 2006. 2. Mickle KJ, Steele JR, Munro BJ. The feet of overweight and obese children: are they flat or fat? Obesity 14(11):1949-53, 2006. 3. Powell M, et al. Efficacy of custom foot orthoses in improving pain and functional status in children with juvenile idiopathic arthritis: a randomized trial. J Rheumatol 2005;32(5):943-50. 4. Evans AM. The flat-footed child—to treat or not to treat. What is the clinician to do? J Am Podiatr Med Assoc 98(5):386-393, 2008. 5. Selby-Silverstein L, Hillstrom HJ, Palisano RJ. The effect of foot orthoses on standing foot posture and gait of young children with Down’s Syndrome. NeuroRehabilitation 2001, 16(3):183-93 6. Stacoff A, Reinschmidt C, Nigg BM, van den Bogert AJ, Lundberg A, Denoth J, Stüssi E. Effects of foot orthoses on skeletal motion during running. Clin Biomech (Bristol, Avon). 2000 Jan;15(1):54-64. 7. Woodburn J, Barker S, Helliwell PS. A randomized controlled trial of foot orthoses in rheumatoid arthritis. J Rheumatol 2002 Jul;29(7):1377-83. 8. Landorf KB, Keenan A, Herbert RD. Effectiveness of foot orthoses to treat plantar fasciitis: a randomized trial. Arch Intern Med 2006;166 (12):1305–10. 9. Woodburn J, Helliwell PS, Barker S. Changes in 3D joint kinematics support the continuous use of orthoses in the management of painful rearfoot deformity in rheumatoid arthritis. J Rheumatol 2003 Nov;30(11):2356-64. 10. Burns J, Crosbie J, Hunt A, Ouvrier R. The effect of pes cavus on foot pain and plantar pressure. Clin Biomech (Bristol, Avon) 2005 Nov;20(9):877-82. 11. Redmond A, Lumb PSB, Landorf K. Effect of cast and noncast foot orthoses on plantar pressure and force during normal gait. JAPMA 90(9):441-449, 2000. 12. Nester CJ, Liu AM, Ward E, Howard D, Cocheba J, Derrick T, Patterson P. In vitro study of foot kinematics using a dynamic walking cadaver model. J Biomech 2007;40(9):1927-37 13. Sheehan FT, Seisler AR, Siegel KL. In vivo talocrural and subtalar kinematics: a non-invasive 3D dynamic MRI study. Foot Ankle Int 2007 Mar;28(3):323-35.