Comparison Study SAFOs and AFOs

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Comparison of Silicone-Ankle-Foot Orthoses vs Plastic Ankle Foot

Orthoses in subjects with Lower Motor Neurone Lesions using the CODA

mpx30 gait analysis system.

McLachlan B.Sc.(Hons), MBAPO; Barry Meadows BSc, PhD, CEng,

EurIng, CS, MIMechE, MIPEM, FISPO

Introduction

The objective of this study was to compare the performance of Silicone

Ankle Foot Orthoses (SAFOs) with Plastic Ankle Foot Orthoses (AFOs). The

SAFO is manufactured completely from silicone and has been claimed to be

of benefit to patients with flaccid drop foot. Previous studies have

supported the reduction in energy expenditure in patients using these

devices although little is understood with regard to how the shortened

lever arms and more flexible material of the SAFO compares to that of

the AFO.

Method

Six patients were selected with lower motor neurone lesions, previously

successfully supplied with AFOs. Each individual was assessed, cast and

fitted for a custom made SAFO. The individuals were instructed to wear

the SAFO for a minimum period of four weeks. They then returned for gait

analysis using the CODA mpx 30 gait analysis system. Analysis of three

conditions was then performed, un-braced, with AFO and with SAFO.

Six gait cycles were averaged for the kinematic data, a total of seven

kinematic parameters and three kinetic parameters were examined. The

significance level was set as p<0.01 (99%)

Results

Significant differences were noted between the UN-braced and SAFO

condition during maximum plantarflexion in swing and maximum hip flexion

in swing. Also significant differences were noted between the AFO vs

UN-braced condition in ankle angle at 98% of gait cycle, maximum knee

flexion in stance and maximum plantarflexion in swing. Differences were

noted at the p<0.01 in the AFO vs SAFO condition in ankle angle at 98%

of gait cycle, maximum hip flexion in swing, maximum knee flexion in

stance and maximum plantarflexion in swing.

Maximum knee flexion during swing was found to be significantly less in

the SAFO condition than in the AFO condition (p=0.015).

Conclusions

Despite the AFO providing greater control of ankle plantarflexion, the

SAFO significantly reduced maximum knee and hip flexion during swing

when compared to the AFO condition.

This comparative study has found significant differences in gait

characteristics within the patient group selected between two very

different designs of AFO.

References:

The use of a silicone boot orthosis on the speed and effort in walking

in patients with lower motor neuron lesions. , PA ,Morant, S.,

Watts R., Swain ID.,The 10th World Congress of the International Society

for Prosthetics & Orthotics, 1st-6th July 2001

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