CENTER OF PRESSURE ON DIABETIC SUBJECTS WITH ROCKER SOLE SHOES Reporter: I-Wei Lin Advisor: Sai-Wei Yang

Outline Introduction Hypothesis and assumption Material and method Preliminary result Future work

DM foot problem pressure Shear force callus ulceration necrosis amputation DM foot neuropathy vasculopathy Rocker shoes will often be prescribed for DM patient to prevent ulceration

Introduction of rocker shoe Apex of the rocker can be placed proximal to the site of ulceration, thus alleviating significant plantar pressures Rigid rocker sole reduces pressure and impact shock

MPJ ROCKER inhibits the demand for dorsiflexion of the toes MET-HEAD ROCKER reduces ground-reaction force ANKLE JOINT ROCKER decreases ankle motion demand HEEL ROCKER is used in conjunction with an increase of the heel pitch to shift weight forward

Literature review For the metatarsal heads: The best average rocker axis location was in the region of 55-60% of shoe length For the toe: 65% of shoe length shoes height, shoes angle, pressure relief Schie et. al.,2000 Insatiability The axis from 55% to 70% of foot length, the load-bearing move from the heel to the medial region Relief of peak pressure at the heel may be related to increase comfort with rocker soles Jun et.al %

Mueller found an 11% reduction in step length with rocker sole use Peterson reported that heel impact loads were four times greater in rocker shoes than in athletic shoes Schaff et al. found peak pressures on the forefoot decreased medially and increased laterally, with significant changes in temporal parameters Xu et al. found changes in center of pressure (COP) locus related to the heel design of the rocker sole Other literature review

Why use forefoot and heel rocker? Cop velocity & Pressure time integral Pressure-time integrals of DM DM subjects shows greater PTI in heel and forefoot region

Design rocker shoe

Purpose of the study To investigate the effect of heel to toe rocker shoe with different apex locus for the DM subjects in pressure relief and Cop altering Hypothesis: –Heel-to-toe rocker soles will contribute to plantar pressure relief and alter the gait pattern of DM subjects

Material and method VICON motion system –Marker set: Modified Helen Hayes –Sampling rate: 120 Hz AMTI force plate – 3 force plates –Sampling rate: 960 Hz Footscan –Synchronization with forceplate –Sampling rate: 500 Hz Pedar 10 m 1.2 m forceplate

Material and method Conditions –Level walking –Barefoot –Shoes Baseline shoe(the flat sole without rockers) 55% rocker shoe 60% rocker shoe 65% rocker shoe

Informed consent and Questionnaire Basic measurement: foot geometry range of motion sensitivity Plantar pressure Motion capture Barefoot 55% rocker shoes 60% rocker shoes 65%Rocker shoes Assign randomly Baseline shoes Flow chart

Preliminary results

Subjects basic data Sex: Male 8 Female: 8 Age:58.2 ± 7.2 y/o Height: 159 ± 5 cm Body Weight: 66.7 ± 15.5 kg BMI:26.1 ± 1.5 kg/m 2

Rocker shoes increase in cadence

Rocker shoes maintain walk speed

Pedar Baseline shoes Rocker shoes

* * * * * 1.Maximum force and peak decrease in heel and forefoot region! 2.Force increase in mid foot 3.60% and 65% do not show a significant difference

* * * ** Peak pressure decrease in heel and forefoot region, especially with 60% and 65%rocker shoes

Rocker shoe can decrease heel and most of forefoot region in contact area. Rocker shoe can decrease forefoot region in pressure time integrals.

Peak pressure Center of Pressure,COP

The load pathway (Gait line or center of pressure COP)

CoP velocity & acceleration T1 T2 T3 T4 T5 T6 T7T8

Bare Baseline 55rocker 60rocker 65rocker

Conclusion In spatial temporal parameter, rocker sole increase in cadence but decrease in walk speed 60% and 65% rocker shoes show a great pressure relieve than 55% rocker shoes All rocker shoes will shift load-bearing to mid foot and increase mid foot contact area Effects of55% 60% and 65% rocker shoes are not consistent, the reason might be the pivot of 55% rocker shoe is in the mid foot area and others are around 1 MTH

Conclusion In Cop analysis V2(correspond to the ankle rocker velocity of gait) decreased and didn't change in cadence and walk speed which means rocker shoes assist in propulsion and save the expenditure of ankle joint. 60% 65% heel-to-toe rocker shoes may apply to high plantar pressure in fore foot and heel region heel-to-toe rocker shoes do not fit for high risk of mid foot ulceration of DM patient (eg.Charcot foot deformity)

References Wu, W. L., Rosenbaum, D., Su, F. C., (2004). The effects of rocker sole and SACH heel on kinematics in gait. Med Eng Phys. 26(8): Brown, l. D., Wertsch, J. J., Harris, G.F., Klein, J., Janisse, D., (2004) Effect of rocker soles on plantar pressures. Arch Phys Med Rehabil, 85:81-6. Myers, l. K., A., Long, J. T., Klein, J.P., Wertsch, J. J., Janisse. D., Harris, G.F.,(2005) Biomechanical implications of the negative heel rocker sole shoe: Gait kinematics and kinetics. Gait & Posture, In Press, Corrected Proof, Available online 21 November 2005 Mueller, M.J., Strube, M.J., Therapeutic footwear: enhanced function in people with diabetes and transmetatarsal amputation. Arch Phys Med Rehabil 1997;78:952-6 Mueller, M. J., Sinacore, D. R., Hoogstrate, S., and Daly, L., Hip and ankle walking strategies: effect on peak plantar pressures and implications for neuropathic ulceration, Arch. Phys. Med. Rehabil., vol. 75, pp. 1196–1200, Schie, l. C. V., Ulbrecht. J. S., Becker, M.B., Cavangh, P. R.,(2000) Design Criteria for Rigid Rocker Shoes, Foot & Ankle International, 21:

Jun, I. S., Joo. C. J. P.,Park. S. B.,Oh. S. G., Lee. S. J., The relationship between peak plantar pressure and comfort using the rocker shoes Van Bogart J. J., Long J. T., Klein J. P., Wertsch J. J., JanisseD. J. and Harris G.F., (2005). Effect of the toe-only rocker on gait kinematics and kinetics in able-bodied persons.IEEE Trans Neural Syst Rehabil Eng 13(4): Vaughan. C. L., Davis B. L., O.Connor. J C., Dynamics of human gait. (1999). Kiboho Publishers W. Brand, "Management of the insensitive limb," Physical Therapy, vol. 59, pp. 8-12, ; 45: Appendix B