Foot Shape and Its Effect on Functioning in Royal Australian Air Force Recruits. Part 2: Pilot, Randomized, Controlled Trial of Orthotics in Recruits with Flat Feet

Military Medicine, Jul 2005 by Esterman, Adrian, Pilotto, Louis

As part of a larger study of the effect of foot shape on functioning, 47 Royal Australian Air Force recruits with flexible flat feet who were embarking on a 10-week basic training course took part in a randomized controlled trial of orthotic therapy. In particular, recruits were assigned at random to an untreated group or a group that received Australian Orthotics Laboratory, three-quarter-length, flexible, shoe inserts. The groups were assessed at baseline and week 8. Outcome measures included pain, injury, foot health, and quality of life. The untreated group (n = 22) had a greater proportion of heavier recruits than did the treated group (n = 25). There were no significant differences in outcome measures at baseline. Only one-half of the group assigned to orthotic therapy wore the orthotics most or all of the time. At the end of the trial, although the results were not statistically significant, those who were provided with orthotics and wore them had the least lower limb pain and the best general foot health and quality of life. Notably, none of the recruits who wore their orthotics most or all of the time sustained a training injury.

Introduction

Flat feet have historically been of concern to military forces.1 Documented restrictions on recruitment for men with flat feet date back at least to the U.S. Civil War.2 However, there is little in the way of documentary evidence regarding how these restrictions arose or what the consequences of accepting recruits with flat feet are.

Flat feet are not necessarily symptomatic, because the foot adapts by changing the shape of the bones and by stretching the ligaments. The structural changes that commonly accompany flat feet, however, affect the normal biomechanics of the lower limbs, causing excess pronation. Pronation is a normal part of the gait cycle; however, people with flat feet tend to overpronate, as part of the compensatory adaptation to this condition.3

There is controversy over the need to provide treatment for flexible flat feet and the ability of health care professionals to provide effective treatment for the condition. The most common treatment for flexible flat feet among adults is orthotics or shoe inserts. The orthotics may be rigid and designed to control function, soft to help absorb shock, or semi-rigid to provide for dynamic balance of the foot.4 The rigid types are usually expensive, because they are prescribed by a podiatrist or orthotist and are made from molds of an individual's feet. Soft or semi-rigid orthotics are available from pharmacies and sports stores without prescription.

There are few studies that have examined the use of orthotics in the management of flat feet. Although some studies demonstrated that orthotics are successful in reducing excess pronation among subjects with flat feet,5,6 there is little or no evidence that this actually improves function.

In the first article of this series, we provided details of a study of Royal Australian Air Force (RAAF) recruits undergoing 10 weeks of basic training at No. 1 Research Training Unit (IRTU) RAAF Edinburgh, a major air force base -25 km north of Adelaide, South Australia.7 Two hundred thirty recruits volunteered for the study, of whom 47 were diagnosed with flat feet. Diagnosis was based on the arch index measured from right static footprints in half-weight-bearing stance. Approximately one-half of those diagnosed with flat feet were selected at random and provided with orthotics. Those with cavus feet, normal feet, and untreated flat feet (N = 205) formed the basis of the previously described prospective cohort study.7 In this study, we describe the results of a pilot, randomized, controlled trial of orthotics among the recruits diagnosed with flat feet, namely, the 22 untreated recruits who were also included in the prospective cohort study and the 25 additional recruits who received orthotics.

Methods

Study Design

The study was designed as a randomized controlled trial. However, the sample size is small and we consider it to be a pilot study, because little is known about the management of flat feet among military recruits or the feasibility of providing orthotics for this purpose.

Study Hypothesis

We hypothesized that recruits with flat feet who were provided with orthotics would have lower rates of pain and injury, better foot health, and better quality of life at the end of basic training than recruits with flat feet who were untreated.

Inclusion and Exclusion Criteria

All recruits who were attending IRTU for basic training and were diagnosed with flat feet were eligible for the study. The only exclusion criterion was already wearing orthotics on arrival at 1RTU.

Diagnosis of Foot Shape

Diagnosis was undertaken on the first day of their course. Full details are provided in the accompanying article.7

Orthotics

Orthotics were provided to approximately one-half of the recruits at random. The RAAF podiatrist, senior medical officer, physical training instructors (who fit the boots), and orthotics supplier were consulted with regard to the most appropriate orthotics to use. Low-profile orthotics were required to fit into the combat boots. Because it was necessary for the recruits to wear the orthotics immediately, flexible or semi-rigid orthotics were required; rigid orthotics would have taken too long to wear in. The orthotics chosen were Australian Orthotics Laboratory (Australian Orthotics Laboratory, International, Kirrance, New South Wales, Australia), three-quarter-length, flexible, shoe inserts with the following properties: heat-moldable plastic, 4-degree rearfoot varus wedge, midtarsal joint stabilization, balanced 4-degree forefoot wedge, second, third, and fourth dorsal metatarsal alignment, and 15-mm calcaneal heel cup.