NEW YORK (Reuters Health) – New research indicates that when it comes to children’s shoes, the size listed by the manufacturer is rarely the true size. In nearly all cases, the manufacturers overstate the size, according to findings presented this week at the American Academy of Orthopedic Surgeons annual meeting in Las Vegas.

“The most striking finding of our study was that the majority of outdoor shoes and slippers of children were too small,” senior author Dr. Norman Espinosa, from the University of Zurich, Switzerland, told Reuters Health. “Interestingly, the shoe sizes given by the manufacturers almost never matched with the true sizes measured by us.”

Another interesting finding, he added, is that the prevalence of hallux valgus deformity among the children studied was higher than previously reported. “This is best explained by the fact that the incidence and prevalence of hallux valgus deformity among children could vary in different countries.”

The results stem from a study of 248 school children from an area in Switzerland who had the inner length of their shoes, the length of their feet, and the hallux valgus angle measured.

The manufacturer-listed shoe size was converted into length in millimeters by multiplying the size by 6.67 millimeters. Perfect-fitting shoes were defined as those in which the inner shoe length exceeded the subject’s foot length by at least 10 mm, with the ideal being 12 mm. Normal hallux valgus angles were considered as 15 degrees or less.

For outdoor shoes, 33.9% fit perfectly, 52.8% were too small, and 13.3% were too big, the report indicates. The corresponding percentages for slippers were 28.2%, 61.6%, and 10.2%.

Just 7.6% of outdoor shoes had a correctly stated shoe size. For 90.2% of shoes, the actual size was smaller than that listed by the manufacturer. The results were even more striking for slippers: only 2.4% had a correctly stated size and 97.6% were too small.

Overall, 3.3% of children had an abnormal hallux valgus angle.

When shopping for shoes, parents should have their children’s feet re-measured by the vendors, Dr. Espinosa emphasized. “Based on this study we know that we should focus on education in order to prevent early onset of juvenile foot deformity.”