http://www.jfootankleres.com/content/6/1/42

Hallux valgus and plantar pressure loading: the Framingham foot study

Andrew M Galica^1†, Thomas J Hagedorn^1†, Alyssa B Dufour¹²³, Jody L Riskowski⁴, Howard J Hillstrom⁵, Virginia A Casey¹ and Marian T Hannan^123*

Journal of Foot and Ankle Research 2013, 6:42  doi:10.1186/1757-1146-6-42

The electronic version of this article is the complete one and can be found online at: http://www.jfootankleres.com/content/6/1/42

Received:	1 July 2013
Accepted:	10 October 2013
Published:	20 October 2013

© 2013 Galica et al.; licensee BioMed Central Ltd.

This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background

Hallux valgus (HV), a common structural foot deformity, can cause foot pain and lead to limited mobility. The purpose of this study was to evaluate differences in plantar pressure and force during gait by HV status in a large population-based cohort of men and women.

Methods

A trained examiner performed a validated physical examination on participants’ feet and recorded the presence of hallux valgus and other specific foot disorders. Each foot was classified into one of four mutually exclusive groups based on the foot examination. Foot groups were: (i) HV only, (ii) HV and at least one additional foot disorder (FD), (iii) no HV but at least one other FD, and (iv) neither HV nor FD (referent). Biomechanical data for both feet were collected using Tekscan Matscan. Foot posture during quiet standing, using modified arch index (MAI), and foot function during gait, using center of pressure excursion index (CPEI), were calculated per foot. Further, walking scans were masked into eight sub-regions using Novel Automask, and peak pressure and maximum force exerted in each region were calculated.

Results

There were 3205 participants, contributing 6393 feet with complete foot exam data and valid biomechanical measurements. Participants with HV had lower hallucal loading and higher forces at lesser toes as well as higher MAI and lower CPEI values compared to the referent. Participants with HV and other FDs were also noted to have aberrant rearfoot forces and pressures.

Conclusions

These results suggest that HV alters foot loading patterns and pressure profiles. Future work should investigate how these changes affect the risk of other foot and lower extremity ailments.

Background

Hallux valgus (HV), a structural foot deformity often resulting in a reactive soft tissue bunion, can cause foot pain and limited mobility [1]. Women are twice as likely to have this condition [2,3] and older adults have a higher prevalence of HV (23% aged 18–25 years versus 35.7% over age 65 years) [4]. Footwear has also been implicated in the development of HV; especially shoes with higher heels or improper fit [5].

The degree to which foot anatomy or biomechanics influence HV is poorly understood. In a 2012 systematic review and meta analysis, Nix et al. reported that the first intermetatarsal angle and first metatarsal protrusions distance were significantly associated with hallux valgus, but also noted that a number of radiographic factors were not significantly associated with hallux valgus [6]. Arch height is noted as an area of interest in clinical models of hallux valgus [7], which often cite low arches as a contributing factor. However, past research has yielded inconsistent results [6]. While Nguyen et al. found a significant association between a clinical assessment of pes planus and hallux valgus in men [2], Kilmartin et al. reported no relation between arch height and hallux valgus when using an arch index [8]. Similarly, studies are inconsistent regarding whether a curved joint head was [9] or was not [10] associated with HV.

Studies that report on plantar pressure distributions for individuals with and without HV are also inconclusive. For example, loading at the hallux may be reduced [11-13], increased [14], or unaffected [15] by the presence of HV. These studies were limited by small sample sizes [14-16] and narrow age ranges [15,17], as well as exclusions of severe clinical cases [14], men [18] , and feet with multiple foot disorders [18].

Prior studies are limited by conflicting results, small sample sizes, and consideration of hallux valgus in isolation of concurrent foot disorders. Addressing these limitations can impact clinical decision making and evaluation of treatment strategies. The purpose of this study is to describe plantar pressures and forces in a large epidemiologic, population-based study of older adults and to investigate whether these measures differ between those with and without HV and other foot deformities. We hypothesized that the presence of HV is associated with decreased loading under the hallux and resultant offloading under the forefoot.