Research Backs Weight-bearing Casting Methods
PERSPECTIVE
Jeffrey D. Olsen
Time and again, the weight-bearing casting method has been shown to be the most reliable, accurate, and effective process for creating custom-made foot orthotics.
Subtalar Neutral (Non-weight-bearing) Approach Flawed
In the 1970s, Root revolutionized the way podiatrists, physical therapists, and orthopedists managed foot and ankle problems. His two systems of analysis for fabricating rigid orthotics included non-weight-bearing goniometric measurement and palpation of the ankle to find an ideal neutral position.1’2 However, a 2002 literature search conducted by Kevin Ball, PhD, and Margaret Afheldt, PT, questions the rationale for neutral casting and the resulting rigid orthotics.3
Although Roofs methods for evaluating subtalar neutral and non-weight-bearing casting are well referenced, Ball and Afheldt clearly demonstrate that Roofs original paradigm, and all subsequent variations based upon this paradigm, are flawed as follows:
1.Non-weight-bearing subtalar neutral approach is not reliable. Elvera et al. found that 14 experienced clinicians could not establish a consistent level of interexaminer reliability.4
2.Roofs definition of subtalar neutral does not ac-
curately represent the position of the foot and ankle
during dynamic weight bearing. Two different studies
have shown that while measuring the stance phase of gait
in normal individuals, the subtalar joint rarely reaches the subtalar-neutral position.5’6
3.The subtalar-neutral position is not functionally significant during normal gait patterns. McPoil and Pierrynowski found that the standing foot posture at rest, not Roofs subtalar neutral, best represents the actual position of the rearfoot during the gait cycle.5’6
Donald Baxter, MD, the past president of the American Orthopedic Foot and Ankle Society, has expressed his belief that “the ‘neutral’ or ‘corrected’ subtalar position is ill-defined and not physiologically reproducible. Furthermore, the subtalar joint ranges through nearly 40 degrees of motion during running and we can’t determine which of these 40 degrees is the ‘correct’ position for each athlete.”7 Lisa Lattanza, PT, says that if “subtalar joint motion, particularly eversion as a component of pronation, is measured in NWB [non-weight bearing] rather than FWB [full weight bearing] 37% of the available ROM may be overlooked.”8 And Dana J. Lawrence, DC, editor of the Journal of Manipulative and Physiological Therapeutics (JMPT), says that “assessing joint play is based in paid on the assumption of a neutral position for the subtalar joint, yet no clear understanding of that neutral position exists.”9
Rigid Orthotics Inferior to Flexible
With few exceptions, long-term immobilization of functional units of the human body has negative health consequences. The majority of rigid inserts, based largely on neutral evaluations pro-
posed by Root, are used to reduce normal ranges of motion and inhibit neurological inputs. Orthotics based on the Root system are very likely to place the foot in a position of supination with a risk of overcorrection, altered forces, and the development of osseous deformations.10
Why Weight-bearing Works
Monte H. Greenawalt, DC, DABCO, explains the success of and rationale for using the weight-bearing, foam casting procedure as follows:
In explaining the casting procedure to your patients, it may be helpful to compare the method to repairing a flat tire. Note that a mechanic doesn’t put a car on the hydraulic
lift to determine which tire is flat; it is apparent only in the position of function. Likewise, fallen arches or dropped metatarsals would not be evident if the foot were cast in a non-weight-bearing position.11
When the feet are flat on the ground, the body represents a closed kinetic chain. From a cast showing the foot in full contact, a skilled technician can determine the amount of hyperpronation, plastic deformation in all three arches, abnormal weight bearing, and foot misalignment. Plastic deformation is the process in which supporting connective tissues are stretched beyond their natural limits, creating permanent stretch. This is what happens to the feet with age and/or trauma. A weight-bearing analysis records functional deformation, and orthotics or footwear made from that analysis provide proper fit and accurately represent arch placement when the patient is standing.
In his landmark text, Essentials of Skeletal Radiology, Terry Yochum, DC, says, “To prescribe the most effective [orthotic] support, use of a weight-bearing casting method to obtain quantifiable information on the extent of pedal imbalance is recommended... This method also results in a more accurate fit, since the fine length and width of the foot during the closedchain stance are thoroughly assessed.”12 And John Danchik, DC, has written that a “professional examination including weight-bearing casting of both feet will provide real-life, position-of-function information for use in constructing a corrective orthotic device.”13
Research Proves: Flexible Orthotics Superior to Rigid
Over the past decade, flexible orthotics in general have been shown to exhibit superior qualities in the areas of shock absorption1415, treatment ofpatellofemoral pain syndrome16, and lower-limb kinematics during walking and running.17 In the past eight years, Foot Levelers’ custommade, functional orthotics in particular have been shown to:
• Reduce pronation18
• Reduce the damaging effects of heel-strike shock18
• Decrease angles in the pedal structure that contribute to pes planus19
• Improve structural alignment19-20
• Improve balance (eyes open)21
• Improve proprioceptive balance (eyes closed)21
• Improve dynamic function21-22
• Improve athletic performance23
Conclusion
The weight-bearing, position-of-fimction method of casting produces an orthotic that is superior to those made by the nonweight-bearing [neutral] system. Custom-made, flexible orthotics are used to correct, support, align, and prevent dysfunction or improve function of movable body parts.24 The research cited in this article proves that custom-made, functional orthotics have a positive effect on weight-bearing foot alignment and the joints and structures above it.
Improving the pedal foundation can have a very positive effect on the whole kinetic chain—the foot/ankle complex, knees, pelvis, and spine. Reducing biomechanical stress helps reduce pain and discomfort.
Foot Levelers’ orthotics not only improve biomechanical support, but they also are highly rated for comfort and effectiveness. In a recent survey, 79% of patients wealing Foot Levelers’ orthotics were satisfied with them.25 Prescribing orthotics is a proven asset for the growth of a chiropractic practice.
References
1. Root ML, Orien WP, Weed JH. Biomechanical Examination of the Foot. Los Angeles, CA: Clinical Biomechanics Corp., 1971.
2. Root ML, Orien WP, Weed JH. Normal and Abnormal Function of the Foot. Los Angeles, CA: Clinical Biomechanics Corp., 1977.
3. Ball KA, AfheldtMJ. Evolution of foot orthotics—parts 1 & 2. J Manip Physiol Ther 2002; 25(2):116-134.
4. Elveru RA, Rothstein JM, Lamb RL. Goniometric reliability in a clinical setting. Subtalar and ankle joint measurements. Phys Ther 1988; 68(5):672-677.
5. McPoil TG, Cornwall MW. Relationship between neutral subtalar joint position and pattern of rearfoot motion during walking. Foot Ankle Int 1994; 15(3): 141-145.
6. Pierrynow ski MR, Smith SB. Rear foot inversion/eversion during gait relative to the subtalar neutral position. Foot Ankle Int 1996; 17(7) :406-412.
7. Baxter DE et al. The ideal running orthosis: a philosophy ofdesign. Biomechanics 1996; 3(3): 42.
8. Lattanza L et al. Closed vs. open kinematic chain measurements of subtalar joint eversion: implications for clinical practice. J Orthop Sports Phys 1988; 9:310-314.
9. Lawrence DJ (ed.) The Year Book of Chiropractic 1994. St. Louis: Mosby, 1993:161162.
10. Michaud TM. Foot Orthoses and Other Forms of Conservative Foot Care. Baltimore: Williams & Wilkins, 1993.
11. GreenawaltMH. Spinal Pelvic Stabilization (4th ed.). Roanoke, VA: Foot Levelers, Inc., 1990; 35.
12. Yochum TR, Rowe LJ, Barry MS. Natural history of spondylolysis and spondylolisthesis. In Essentials of Skeletal Radiology (2nd Ed.). Baltimore: Williams & Wilkins, 1996. 364.
13. DanchikJ. Foot stability and athletic performance. Sports Talk 1995; 8(3): 35.
14. NiggBM, Nurse MA, Stefanyshyn DJ. Shoe inserts and orthotics for sport and physical activities. Med Sci Sports Exerc 1999; 31(7 Suppl) :S421-S428.
15. Schwelhms MP, Jordaan G, Noakes TD. Prevention of common overuse injuries by the use of shock absorbing insoles: a prospective study. Am J Sports Med 1990; 18(6) :636-641.
16. Eng JJ, Pierrynow ski MR. Evaluation of soft foot orthotics in the treatment ofpatellofemoralpain syndrome. Physical Therapy 1993; 73:62-69.
17. Eng JJ, Pierrynow ski MR. The effect of soft foot orthotics on three-dimensional lowerlimb kinematics duringwalking card running. Phys Ther 1994; 74(9):836-844.
18. Hyland JK, Yochum TR, Barry MS. Bone marrow edema and postural misaligrrment: a preliminary report. Success Express 1996;
16(3): 13.
19. Kuhn DR, Shibley NJ, Austin WM, Yochum TR. Radiographic evaluation of weightbearing orthotics and their effect on flexible pesplanus. JManip Physiol Ther 1999; 22(4):221-226.
20. Kuhn DR Yochum TR, Cherry AR Rodgers SS. Immediate changes in the quadricepsfemoris angle after insertion of an orthotic device. J Manip Physiol Ther 2002; 25(7):465-470.
21. Stude DE, Brink DK. Effects of nine holes of simulated golf and orthotic intervention on balance andproprioception in experienced golfers. J Manip Physiol Ther 1997; 20:590-601.
22. Stude D, GullicksonJ. Effects of orthotic interventionandnine holes of simulated golf on gait in experienced golfers. JManip Physiol Ther 2001; 24(4):279-287.
23. Stude D, GullicksonJ. Effects of orthotic interventionandnine holes of simulated golf on club-head velocity in experienced golfers. J Manip Physiol Ther 2000; 23(3):168-174.
24. Levitz SJ. Biomechanicalfoot therapy. Clinics in Pod Med & Surg 1988; 5:3.
25. Duarte MA, Cambron JA. Orthotic insole use andpatient satisfaction in an outpatient chiropractic clinic. JChiroEd2004; 18(l):50.
26. Smith-Oricchio K, Harris BA. Interrater reliability of subtalar neutral, calcaneal inversion and eversion. JOSPT1990; 12(1): 13.
Dr. Jeff'ey D. Olsen is a 1996 Presidential Scholar and summa cum laude graduate of Palmer College of Chiropractic. Dr. Olsen has been in private practice with his two partners brothers since 1997, in Roanoke, VA. In addition, Dr. Olsen has instructed as an adjunct faculty member at the College of Health Sciences in Roanoke, teaching Anatomy and Physiology in the Physician Assistant department.
