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These papers were presented yesterday at the ACR Conference:
Hallux Valgus and Foot Bimechanics: Relation between Structure and Function.
Andrew M Galica,Alyssa B Dufour,Marian T Hannan,Virginia A Casey, Jocelyn C Frey, Mark W Lenhoff,Howard J. Hillstrom
Background: While there are many clinical and case reported studies of hallux valgus (HV), the etiology and biomechanics of the pathology remain poorly understood. Although previous studies have noted differences in peak pressures in various regions of the foot between individuals with and without HV, results are inconsistent and have not been confirmed in larger studies. The purpose of this research is to describe peak plantar pressures and pressure-time integrals in an epidemiological population-based study and to investigate whether these measures differ between those with and without HV as defined by standardized foot examinations. We hypothesize that it is possible to distinguish individuals with and without HV based on differences in peak pressure and pressure-time integral measures.
Methods: Data were obtained from a subset of participants enrolled in the Framingham Heart Study (N = 464; 57% female; mean age, 65 years; mean BMI, 28). Between 2002 and 2005, plantar pressure values were collected using a Tekscan Matscan system (model 3150, resolution of 1.4 sensels/cm2) while participants walked at a comfortable pace barefoot across the mat. Data was imported into Novel software and masked into 12 segments (toes, submetatarsal heads 1-5, medial arch and heel, lateral arch and heel). Peak pressure and pressure time integral values were then calculated. Two-tailed Students T-tests assessed differences between those with and without HV.
Results:
Preliminary analysis revealed significant sex differences in plantar pressures. Therefore, subsequent analyses were stratified by gender. Since the right foot is considered more dominant, only these results are reported. Tables 1 and 2 present a subset of the 12 analyzed foot areas. Female subjects with HV exhibited greater peak pressure values under the lateral arch than those without HV (p = 0.046). No significant differences were found in pressure-time integrals for females with and without HV, regardless of foot area. Male subjects with HV exhibited greater peak pressure (p=0.007) and pressure-time integral (p=0.015) values than those without HV under groupings of the 3rd, 4th, and 5th toes.
Conclusions: Significant gender differences in peak pressures and pressure time integrals were noted. The data did not support our hypothesis as analyses did not distinguish between those with and without HV based on pressure-related measures. It is possible that the accuracy and resolution of Tekscan, in comparison to other foot mat systems, may have affected our results. It is also possible, since both groups contained concomitant pathologies, the plantar loading effects for HV washed out. Future work may investigate whether consideration of additional foot disorders or deformities may better use the plantar pressure measures to distinguish foot pathologies.
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Risk Factors for Hallux Valgus (HV) in a Population-Based Study of Older Adults: The Framingham Foot Study.
Alyssa B Dufour, Virginia A Casey, Andrew M Galica, David R Gagnon, Howard J. Hillstrom, Marian T Hannan
HV is common in older adults, but its risk factors and relation with foot pain are understudied. The few studies of risk factors have reported conflicting results and had small samples, with limited age ranges. Our purpose was to determine if HV is associated with foot pain and potential risk factors in large numbers of community-dwelling older men and women.
This cross-sectional study included 3415 ambulatory adults from the population-based Framingham Study. We used a validated foot exam done by trained examiners with criteria to assess H valgus, foot pain, pes planus, and current and past high heel use. HV was present if the angle of the hallux toward the lesser toes was observed to be >15°. Pes planus was defined using a weight-bearing ratio of arch width to rear-foot width on a computerized pressure mat (y/n if ratio>.75 on either foot). Foot pain (y/n) was queried: “on most days, do you have pain, aching or stiffness in either foot?” High heel use in women was determined by the subject choosing high heels/pumps from a list of 13 shoe types as the shoe most typically worn currently and in their past. Past high heel use was categorized into 3 groups: main shoe between ages 20-64y; main shoe at some ages between 20-64y; not worn between 20-64y. Age, sex, and body mass index (BMI, grouped <25, 25-30, >30 kg/m²) were also collected. Sex-specific multivariate logistic regression models were performed to examine the effect of the above risk factors on HV.
1498 men & 1917 women had mean age of 67 ± 10.6 y (range 40-100 y). 20% of men and 41% of women had HV. Current high heel use was not associated with HV in women and thus excluded. Table shows risk factors for HV by sex. Foot pain and older age increased the odds of having HV in both women and men (all p<0.03), even after adjusting for other factors. In women only, having pes planus increased the odds of HV by 70% (p=0.01); BMI>30 was protective, decreasing the odds by 35% (p=.0007); and wearing high heels as main shoe during ages 20-64y increased the odds of HV by 22% (p=0.01), after adjusting for the other factors. To extend the BMI findings, we examined a biomechanical measure (1st met-head peak pressure) in a subset (n=573) and found no interaction with BMI (p<0.56). Adding peak pressure to the model did not change the effects of BMI (ORs∼0.99).
We saw strong relations between HV and foot pain and increased age in both men and women. While current high heel use was not linked to HV, several other factors were associated with this structural foot disorder in women. Results for BMI>30 are in agreement with ≥1 previous study showing a protective effect. Perhaps this is due to differing weight distributions and thus different foot biomechanics in obese women versus those with BMI<25. Future studies should include additional risk factors such as occupational weight bearing load, pregnancies and toe box structure of shoewear.
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Hallux Valgus and Pes Cavus Are Highly Heritable in Older Men and Women: The Framingham Foot Study.
Marian T Hannan,Yi-Hsiang Hsu, L. Adrienne Cupples, Joanne M Jordan.
Foot disorders are common among adults, affecting 20-60% of adults ad often linked to mobility limitations. Although genetics are commonly suspected in foot disorders, only one family aggregation study has been done, reporting that 90% of 350 participants with hallux valgus had a family history, and inheritance may be an autosomal dominant transmission. To our knowledge, no other studies have examined the association between foot disorders and genetics in humans. We have the unique opportunity to link data that we have collected on specific foot disorders to a wealth of genetic data in the community-based Framingham Study. Our aim was to evaluate the possible heritability of two common foot disorders, using the pedigree structure in the Framingham Study.
The Framingham Foot Study (n=2179) was designed to examine common foot disorders and functional limitations. A trained examiner used a validated foot exam to assess 20 foot disorders in 2179 participants between 2002-2005. Of participants, 959 men and 1220 women had been genotyped. We estimated overall, sex-specific and age (< 60, 60+y) heritability of hallux valgus and pes cavus (our most common and least common foot disorders) in the Framingham participants. Hallux valgus (present/absent) was defined as the angular deviation of the hallux with respect to the first metatarsal toward the lesser toes at >=15°. Pes cavus was defined using a digital recording of foot pressure while walking (MatScan pedobarographic device, Tekscan, Inc. Boston MA), that allowed calculation of the ratio of arch width (medial to lateral, to nearest 0.01 cm) to heel width. Pes cavus was defined as either foot as having a weight-bearing arch width=0, regardless of heel width. We estimated heritability of hallux valgus and pes cavus by the threshold model of a standard quantitative genetic variance-components model implemented in the Sequential Oligogenic Linkage Analysis Routines (SOLAR) package.
Mean age was 66y (range 39-99y); 57% were female. The prevalence of hallux valgus (HV) was 31% (675 hallux valgus cases with available pedigree structure). The overall HV heritability was 0.39 for women and 0.38 for men. For persons aged < 60y, the HV heritability was 0.89. The prevalence of pes cavus (PC) was only 7% (154 cases with available pedigree structure have pes cavus). The PC heritability was 0.68 for women and 0.20 for men. For individuals < 60y of age, the PC heritability was 0.99 for women and 0.63 for men. Thus, hallux valgus and pes cavus are highly heritable, especially for younger adults.
This study breaks new ground in an area that has received very little attention, yet is critically important to public health. Our study documented for the first time, the high heritability (strongly suspected by many) of two specific foot disorders phenotypes. Foot disorders are common and it is important to identify persons at high risk, as effective interventions exist and may also be targeted to individuals to lessen the impact of foot disorders or prevent development. Genome-wide association analyses are planned to identify potential genetic determinants for these common foot disorders.
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