Effect of footwear and orthotic devices on stress reduction and soft tissue stra

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Clin Biomech (Bristol, Avon). 2006 Dec 18

Effect of footwear and orthotic devices on stress reduction and soft

tissue strain of the neuropathic foot.

Lott DJ, Hastings MK, Commean PK, KE, Mueller MJ.

Movement Science Program, Washington University, St. Louis, MO, USA;

Applied Biomechanics Laboratory, Program in Physical Therapy,

Washington University School of Medicine, St. Louis, MO, USA.

BACKGROUND: Ground reaction forces from walking result in stress

(pressure) and soft tissue strain at the plantar aspect of the foot.

Excessive plantar pressure and tissue strain on the insensate foot

may lead to ulceration. Our study investigated the effect of

therapeutic footwear and custom-made orthotic inserts on pressure

and tissue strain along the second ray of the plantar foot, and how

these two variables are associated.

METHODS: Twenty subjects (mean age 57.3 [sD 9.3] years, 12 male, 8

female, body mass index 32.5 [sD 7.4] kg/m(2)) with diabetes

mellitus, peripheral neuropathy, and a history of a plantar ulcer

participated. Plantar pressure data were recorded during computed

tomography scans for four conditions (barefoot, shoe, shoe+total

contact insert, and shoe+total contact insert+metatarsal pad). For

each condition tested, tissue strain and plantar pressure were

determined at the second metatarsal head and at 15 other points

along the second ray.

FINDINGS: Differences were noted between the 4 conditions for

pressure (P<0.004) and soft tissue strain (P<0.042) at the second

metatarsal head. Correlation coefficients demonstrated an

association between pressure and strain (Barefoot r=0.81, Shoe

r=0.75, Shoe+total contact insert r=0.73, and Shoe+total contact

insert+metatarsal pad r=0.44).

INTERPRETATION: Footwear and orthotic devices tested in this study

decreased pressure and soft tissue strain at the second ray of the

foot, and these two variables were strongly related. A better

understanding of the role tissue strain plays in distributing

plantar forces may lead to improvements in the design of orthotic

devices.