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The all-weather walking plaster

J. Shepherd

The Australian Journal of Rural Health © Volume 3 Number 3, August 1995

Aust. J. Rural Health (1995) 3. 101-105

Clinical Perspective

THEALL-WEATHERWALKINGPLASTER

General Practice, Junlestoml : South _4ustralia, Australia

ABSTRACT: This article descl-&es the application of an all-weather- xalking plaster- designed

spec$cally LO meet the needs of rural patients. It outlines the uduantages of t1zi.s method oner

traditional plaster applications.

KEY WORDS: plaster of Paris, rural genes-al practice.

INTRODUCTION

The ability to construct a walking plaster that is

wet-grass proof, stable am1 allows the patient to

walk, TLIII and work safeb with animals on uneven

ground is an extremely useful skill for rural GPs

to acquire and appl!- to their patients.

While working as orthopaeclic registrar at the

Winchester Hospital in 197.5-76. the benefits of

vigorous mobilisation inside well fitting plasters

were impressed upon me. Repair of acutel!- rup-

tured collateral ankle ligaments was considered

unwarranted because of excellent a&\-e conserv-

ativ~e treatment results from well made plasters.

With critically timed manoeu\-res. the plaster

technician always ensured that the plaster sole

had good application to the instep. and fitted

flatly on the inside of a canr-as boot I(onl!- at the

hee1 and metatarsal heads). He then applied a

thin skin of fibreglass to prol~icle strength and

splash-proofing to the comfortably- moulded plas-

ter of Paris (POP).

On commencing rural practice in the mid-

north of South Australia in 1978. and in the

absence of beautifully made English canms plas-

Correspondence: J. Shepherd, 66 IrCne Street,

Jamestown, SA 5491, .%crstralia.

Acceptedfol-publication Februuq. 1995.

ter boots, I soon found that plasters constructed to

provide a boat or rocker shaped bottom were

vastly superior in durabilit~~ and function to the

old fashioned rubber heels. Rubber heels alwavs

wore through unless the>- were on a heaT-\- base

plate of 14-16 la>-em. which took 2 da>-s to dry,

and they were dangerous and slipperT- on shear-

ing shed floors. I therefore ceased using the rub-

ber heels. The we11 constructed: but initially

expensive, 3M, Zimmer or Biomet boots eventu-

ally replaced the tractor tyre boots or heavy

thongs with stapled straps that had been con-

structed by enterprising farmers to increase the

life of their rocker soles.

CONSTRUCTION OF PL-ASTER

ROCKER SOLE MOULDS

Initially I used fibreglass cardboard boxes as a

foot mould. When pressure was applied a slight

depression resulted which usually matched the

shape of commercial plaster shoes. However I

found that students and trainees could rarely bal-

anee this box against their abclomen. and also

position it at right angles to the vertical tibia1

shaft. I therefore used the boots wrapped in Glad-

wrap as the ‘moulds’. These were excellent pro-

vided the plasterer had enough flat abdomen or

unencumbered chest wall to press these on and

102 AUSTRALIANJOURNALOFRURALHEALTH

FIGURE 1: Plaster mould: Shoe mould is applied to

the plaster board.

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or

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- A

:’ \5”

J’

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FIGURE 2: Planter grade or up to 5” dorsijlexion.

observe their correct angles. If the plasterer failed

to achieve the correct angle or the shoe bent then

expensive disasters occurred. Three failures and

$100 worth of plaster and fibreglass (at practice

expense) applied by one Family Medicine Pro-

gram (FMP) trainee for a sprained ankle con-

vinced me to ask my Chief Executive Officer to

construct rocker sole moulds that would perfectly

match the boots.

The Chief Executive Officer took the mould of

the upper surfaces of three new small, medium

and large plaster boots and imprinted these into

three wooden trays, filled level with POP. The

trays measured 10, 12 and 14 inches long by 7

inches wide and 1 inch deep. Painted with

FIGURE 3: Rehearsing the angles before applying

the POP

Estapol and used as rigid moulds, these trays

have lasted for 6 years and are extremely easy to

hold against the body and to obtain the correct

alignment (Fig. 1).

A similar type mould could be constructed by

using the plaster shoe with wooden wedges sup-

porting each end and nailed onto a flat wooden

board, as it is important to avoid distortion of the

shoe when pressing onto the foot during the mak-

ing of the rocker sole.

CONSTRUCTION OF PLASTER TO

FIT THE MOULDING BOARD

Prerequisites

Removal of swelling by elevation and serial com-

pression bandaging, with coaxing of the foot to

plantar grade and up to 5 degrees of dorsiflexion

is a fundamental requirement (plasters set in

plantar flexion deny normal gait pattern: Fig. 2).

Rehearsal

The patient’s stockinette and velband should only

be applied aIter achieving the 5 degrees of dorsi-

flexion, following the application of pressure

against the pectorals or lower ribs on the plas-

ALL-WEATHER WALKING PLmISTER: J. SHEPHERD 103

FIGURE 4: Afoulding- the POP JkrniJ- into the irxicp

and the heel.

terer’s chest to comfortabl~~ fill the instep and

avoid eversion or inversion (Fig. 3).

Application

A routine leg POP either abol-e or beloT\- the knee

is then applied, with an eight thickness slab

extending as far as the middle of the metatarsal

heads, and around the convex heel surface. This

slab must be incorporated into the plaster and

then pushed firmly into the instep as rehearsed

(Fig. 4).

Construction of the rocker

(1) The first requirement is to fill the instep.

Take a fresh roll of 6 inch POP. tear off two. three

thickness slabs 6 inches long.

(2) One slab is folded diagonallvm once to gi7-e

a large triangle, and the second slab is folded

twice to give a smaller triangle.

(3) These triangles are then moistened ant1

applied to the instep and coaxed to fill in and

provide a level base to the POP (Figs 3. 6).

(4) A multi-lavered ant1 contoured slab (depending upon the length of the foot) is now

constructed with the remainder of the 6 inch roll

(Fig. 7). It is immersed, wrung out, and then

applied and pressed hard onto the sole I~!- the

plaster mould board, with the edges Cgorously

FIGURE 5: Thefilled instep.

FIGURE 6: Filling he inslep.

r

L

FIGURE 7: .IIuking the rocke7- base.

crimped in beneath the margins of the foot to

ensure that the mould is completely filled (Figs 8,

9).

AUSTRALIAN JOURNAL OF RURAL HEALTH

FIGURE 8: Applying the rocker base.

FIGURE 9: Modding the rocker base with the plaster

mould.

(5) When the plaster is almost set, the board

is wriggled slightly side to side to free it from the

plaster and the rocker surface is then firmly ban-

daged on with 12.5 cm fibreglass (Fig. 10). One

roll extending 12-15 cm above the ankle is usu-

ally enough. The POP will fit the boot exactly,

provided the mould is made to match the boot.

A useful trick to increase the durability of the

sole is to apply two longitudinal layers of fibre-

glass to the sole first, starting at the Ieading edge.

The third layer is then run backwards around the

instep and up and over the forefoot to anchor the

FIGURE 10: Fibreglass rocker base.

FIGURE 11: All-weather walkingplasters remain

strong qfier considerable use.

first two layers in place. The application of the

extra layers of fibreglass to the sole of the plaster

usually means that farmers can leave their dirty

thongs or shoes at the door of the house and walk

inside the house on the plaster itself without it

wearing out over 6-8 weeks. Following applica-

tion, 24 hours of non-weight bearing is required.

Graduated walking (depending upon the reason

for POP) is then commenced.

PITFALLS INVOLVED WITH

APPLICATION OF THIS PLASTER

(1) Slight ankle extension (plantar flexion)

which causes breaking of the plaster each side of

the forefoot and cracking and breaking above the

ALL-W-EATHER WALKING PLASTER: .I. SHEPHERD 105

ankle. The patient will also have chafed the front

of their shin.

(2) Rolling back the stockinette over velband

or plaster at either end of the plaster can cause

dangerous constriction bands inside and out of

sight. This can be avoided by radial cuts to any-

protruding velband or plaster before carefully

turning back the stockinette.

(3) Leaving a thick ridge of plaster at the

anterior and lower edge of the sole can cause

painful indentation in the skin of the metatarsal

heads. It is better to leave a tapered edge allow-

ing contact and weight-bearing b!- the front of the

metatarsal heads and toes.

The final test for your plasters will be whether

they last the distance and can still stand by- them-

selves, stable and solid after 200 km of road work

(Fig. 11).