January 2010

In the Moment: Foot Care

by Jordana Bieze Foster

Kids’ shoes come up short

Study links tight fit to hallux valgus angle

Keeping up with the ever-changing footwear needs of growing children can be a challenge for parents, but squeezing kids into too-short shoes may put them at risk for hallux valgus, according to research from the Medical University of Vienna.

In a study of 858 healthy pre-school children, investigators found a significant relationship between shoe length and hallux valgus angle, with the relative risk of lateral hallux deviation increasing as the distance between the toes and the shoe tip decreased. The results were published on Dec. 17 in the online journal BMC Musculoskeletal Disorders.

Alarmingly, the researchers also found that the majority of children in the study wore shoes that were too short, particularly when indoors. Indoor footwear was at least one size too short in 88.8% of 808 children, while outdoor footwear came up short in 69.4% of 812 children. (Shoe sizes refer to European sizing; proper fit was defined as the shoe being 10-12 mm longer than the foot.) The authors suggested that parents may pay less attention to indoor footwear than outdoor footwear, based on pre-school teachers’ comments that indoor shoes were often not replaced at all during the course of a school year.

More than half (57.8%) of 789 children had hallux valgus angles of 4º or more, based on an external footprint-based measurement. Radiographic measurements were not used for ethical reasons.

Wearers of indoor shoes that were one size too short were 17% more likely to have a hallux valgus angle of 4º or more, a relative risk that increased to 37% for shoes that were two sizes too short and 61% for three sizes too short. About 61% of children in the study wore indoor shoes that were two sizes too short.

For outdoor shoes, the increased risk was 5% for one size too short, 10% for two sizes and 15% for three sizes. The authors suggested that the difference in risk between indoor and outdoor shoes might be because the indoor shoes were more likely to be too short, and because pre-school children spend more hours per day wearing indoor shoes than outdoor shoes.

The shoe-fit findings of the Austrian study were consistent with those of a University of Zurich study presented in February 2009 at the annual meeting of the American Academy of Orthopaedic Surgeons. The Swiss research team, which included one of the Viennese authors, studied 148 children between the ages of five and 10, and found that 52.8% of outdoor shoes and 61.6% of indoor shoes were too short.

The Swiss study did not analyze the association between shoe fit and hallux valgus angle, but it did find that 79.7% of 153 children had hallux valgus angles of 5º or more. An angle of more than 15º is typically considered clinically abnormal, but this value was exceeded in 3.3% of children in the Swiss study – more than the previously reported prevalence of 2.5% in a 1991 study of 10-year-olds that used radiographic measurements, published in the British version of the Journal of Bone & Joint Surgery.

Further muddying the picture is the Swiss group’s finding that almost all of the shoes were actually smaller than the size given by the manufacturer. This was the case for 90.2% of 202 outdoor shoes and 97.6% of 209 indoor shoes.

The good news is that research does suggest the effects of too-short shoes can potentially be reversed simply by swapping them out for a better fit. A 1953 British Medical Journal study of 164 schoolchildren found that the number of hallux valgus cases dropped from 31 to 12 after one year of wearing professionally fit shoes; average great toe angle also significantly decreased across all ages.

Posted total contact insoles reduce hindfoot valgus in flexible flatfoot

Total contact insoles with a 5º forefoot post significantly reduce hindfoot valgus angle in adult patients with flexible flatfoot, according to research from Taiwan presented in November at the annual meeting of the Pedorthic Footwear Association.

In 18 subjects with flexible flatfoot, wearing athletic shoes decreased the maximum hindfoot valgus angle from 13.9º to 11.3º compared to a barefoot condition. Adding the TCI further decreased the angle to 9.2º, nearly equivalent to the 9.1º seen in control subjects. The shoe-insert combination also significantly redistributed peak pressure and contact area away from the arch.

“The shoes themselves can correct some pronation, but adding the total contact insole brings it very close to normal,” said Simon F. T. Tang, MD, professor and program director of physical medicine and rehabilitation at Chang Gung Memorial Hospital in Taiwan, who presented the findings.

In an earlier study, published in the November 2003 issue of the American Journal of Physical Medicine & Rehabilitation, the same authors found a mean forefoot varus angle of 5.01º in patients with flexible flatfoot.

Falls prevention efforts in elderly could start with toe strengthening

One way of decreasing the risk of falls in elderly individuals may be as simple as strengthening the toes, according to research from the University of Wollongong in Australia.

In 312 men and women between the ages of 60 and 90, investigators found that those who experienced at least one fall during a one-year follow-up period had significantly less flexor strength than the non-fallers in both the hallux (11.6% BW vs 14.8% BW) and the lesser toes (87.% BW vs 10.8% BW).

Fallers were also significantly more likely than non-fallers to have a lesser toe deformity and more than twice as likely to have hallux valgus.

The results, published in the December issue of Clinical Biomechanics, are consistent with those of a smaller, earlier study from Japan. That study, published in the December 2001 issue of the Journal of Japanese Physical Therapy Association, found that eight weeks of toe motion exercise significantly improved dynamic balance and knee extension strength in 23 older subjects compared to 15 similarly aged controls.

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