Austrian research suggests too-short shoes may contribute to the development of bunions in children, and genetics also appear to play a role. Most clinicians try to avoid surgery in young patients, instead turning to conservative strategies such as foot orthoses and night splints.
By Christina Hall Nettles
Two Austrian studies suggest that juvenile hallux valgus (JHV) is far more prevalent in young children than previously recognized and that the culprit is too-short shoes. But will this relationship apply to children in other countries?
Christian Klein, MD, Elisabeth Groll-Knapp, PhD, Michael Kundi, PhD, and Wieland Kinz, PhD, of the Institute for Environmental Health, Center for Public Health, at the Medical University of Vienna, recorded the hallux angle and length of 1579 individual feet among preschool children aged 3 to 6.5 years.1 Fewer than 25% of the children’s feet exhibited a straight position of the great toe, with the majority displaying lateral deviations at different degrees. The “great toe varied between a straight position and a hallux angle of up to 19°,”1 according to the researchers, who stated there were no known evidence-based normal values and ranges of hallux angle for “children of such a young age, either based on radiographic measurements” or on data using their external method.
Investigators stratified the study sample’s 858 participants by gender, geographic location (urban vs rural), and Austrian province and performed upright 3D measurement of the children’s feet using an external method based on footprints (to avoid exposing healthy children to x-rays). They then randomly selected days to measure the inside length of the children’s indoor and outdoor shoes and compared those measurements with the length of the feet. Nearly 90% of the participants’ indoor shoe sizes were too short, and nearly 70% of the children wore outdoor shoes of insufficient length.1
“We showed that there is a significant relationship between too-short shoes and the hallux angle; the shorter the shoe, the higher the value of the hallux angle. Although currently we are not able to tell which dosage is harmful, for example, four hours per day during two months leading to an angle of fifteen degrees,” Kinz said.
The Austrian Federal Ministry of Health commissioned the same group of researchers to analyze children’s perceptions and parents’ awareness of properly fitted shoes compared with investigators’ measurements.2 They recorded data from more than 496 children aged 6 to 10 years and looked at approximately 1000 pairs of outdoor shoes, slippers, and house shoes. Children were asked to wear one shoe that was several sizes too small, and one shoe that was fitted correctly. Interviewers asked test subjects to walk in both shoes and then questioned them about the experience. They found the participants could not feel a clear difference in fit, and many children described the shoe that was markedly shorter than the foot itself as a good fit.2
“During our research projects and numerous ‘Measuring Days for Kids’ Feet’ held in Germany, Switzerland, and Liechtenstein, we were surprised to see how many children were wearing shoes that were much too short; up to five sizes too small. Oddly, all of these children were entirely convinced that their shoes fit perfectly,” Kinz said.
Shoe sizes increase about a half size every four months in children aged 3 to 5 years, with boys’ feet typically presenting one size longer and one size wider than girls’ feet at the same age.3
“We advise children’s feet need twelve to seventeen millimeters [about one half to three quarters of an inch] of extra space in their shoes. One should measure the length of the feet and also the inner length of the shoes using a homemade cardboard template or a tool such as the plus12,4 a measuring tool we developed for parents,” he added.
The team acknowledged the validity of studies that show heredity, pes planus, metatarsus primus varus, first metatarsal length, and hypermobility of the metatarsocuneiform joint are significant factors in understanding the etiology of JHV. However, they believed no studies of extrinsic factors had investigated a significant relationship between wearing shoes of insufficient length and lateral deviation of the great toe.
Intrinsic vs extrinsic factors
Hallux valgus is the most commonly reported forefoot deformity in adults, yet a 2010 systematic review of papers reporting results of nearly 497,000 participants found its actual prevalence difficult to estimate consistently, and concluded only that the condition is common and is diagnosed more often in women and with increasing age.5
In juvenile imaging studies, normal hallux valgus angles range below 16°, and a normal intrametatarsal angle must not exceed 9°,6 but singular measurements may not be enough to make an accurate diagnosis. Juvenile hallux valgus is often bilateral, and an “increased distal metatarsal articular angle may be the defining characteristic of JHV,” according to a 1995 study7 of 60 feet that were treated with a variety of surgical corrections individualized to their specific deformities. Michael J. Coughlin, MD, current clinical professor of orthopedic surgery at the University of California San Francisco and past president of both the American Orthopaedic Foot and Ankle Society and the International Federation of Foot and Ankle Societies, led the investigation.
Coughlin acknowledged the importance of properly fitting shoes, but questioned if studies based in central Europe would apply with equal measure to children in other countries.
“Insufficient length is an interesting factor, but I think it plays a minor role in America, where children have multiple shoes and purchase shoe wear frequently,” Coughlin said. “In adolescent hallux valgus, I believe shoe wear plays a minor role in development and progression of deformity. We specifically asked our patients about shoe wear, and a small percentage felt this was a factor.”
Coughlin’s 1995 study was an 11-year retrospective review of 45 children (60 feet) with JHV. It found that constricting footwear was noted in only 24% of patients, but that nearly 75% of the study cohort inherited the deformity from their mothers.7 The latter finding was supported by a 2010 study of bilateral scarf osteotomy performed in adolescents with JHV, which found 100% maternal inheritance of hallux valgus deformity.8
Coughlin suggested that medical providers evaluating suspected JHV take a family history to determine the incidence of bunion deformities in parents, siblings, and close relatives, and take a closer look at patients with a hallux valgus angle greater than 25° aged between 12 and 14 years.
“Most children with JHV experience onset at ages seven to ten years or earlier. The age of onset is associated with increased severity of deformity. Family history and early onset make a difference in the severity—and often the progression—of deformity,” he told LER.
Coughlin’s research found no increase of pes planus in patients with JHV. Foot pronation may predispose hallux valgus in certain patients, such as those with ligamentous laxity, but research has not quantitatively demonstrated this predisposition.9
In 1993, a critical literature review noted JHV is often inherited and is more common in girls and in shoe-wearing populations, yet studies searching for the etiology of JHV had failed to prove the deformity was a product of the shape and length of the first metatarsal.10 More recent studies have continued exploring the associative or causative relationship of the first metatarsal in JHV.11
Norman Otsuka, MD, Joseph Milgram professor of orthopedic surgery at NYU Langone Medical Center in New York City, and orthopedic surgery resident Rachel J. Shakked, MD, typically see adolescent hallux valgus in female patients with a positive family history.
“Standing radiographs can calculate the intrametatarsal angle to confirm diagnosis, but the main factors in deciding whether to refer a patient for surgical consultation are the presence of pain and the need to significantly modify activities,” Shakked said.
“Diagnosing JHV in younger patients, male and female, is approached similarly—determining whether the foot deformity is painful and affecting activities,” she continued. “Conservative management may be advised unless pain, functional deficit, rapid progression, or other concerning signs are present. In younger patients, we advise nonoperative management when possible, as there is a high recurrence rate of hallux valgus after surgery if a patient is skeletally immature.12 Conservative treatment can include shoe modification to a wide toe box and night splints to abduct the great toe.”
In a 1992 study of 56 children with hallux valgus (aged one month to 16 years), night use of a thermoplastic splint along with exercises were associated with improved metatarsophalangeal joint angle, intermetatarsal angle, or both in about half the feet treated.13 Researchers reported no recurrences among those successful outcomes at follow-up, which ranged from two to six years.
Conservative interventions for hallux valgus may provide relief from symptoms, but may not reverse the deformity, which in some cases may be severe enough to dislocate the first metatarsophalangeal joint, according to Ward M. Glasoe, PhD, PT, ATC, assistant professor in the Physical Therapy Program at the University of Minnesota Medical School in Minneapolis.
Researchers have not been able to determine consistently which conservative interventions are appropriate in children who have not reached skeletal maturity. Glasoe cited a landmark study by Kilmartin et al14 indicating foot orthoses worsened the existing JHV angle in children aged 9 to 10 years, but he noted the study was limited by its use of rigid partial-contact foot orthoses designed to limit hindfoot pronation and by an unverifiable measure of patient compliance.
“More current evidence recognizes the benefits of treating hallux valgus with foot orthoses,” Glasoe wrote in Physical Therapy.15 “Orthoses that bolster the arch and orient the first metatarsal horizontally may work to contain the kinetics and kinematics of the first metatarsal to the sagittal plane.”
“Orthoses posted medially combined with strengthening exercise of the tibialis posterior, in my clinical experience, offer a chance to correct flattening of the arch and excess eversion of the hindfoot and possibly counteract the progression of hallux valgus,” Glasoe said.
Seattle podiatrist Lawrence Z. Huppin, DPM, of The Foot and Ankle Center of Washington, fits custom and customized foot orthoses for children and adolescents with JHV. He, too, looks closely at family history when determining how aggressively to treat young patients with hallux valgus.
“In adolescent patients, our primary goal is to allow the first ray to plantar flex. When we cast for orthoses, we plantar flex the first ray so that the resultant orthosis is more effective at preventing jamming of the first midtarsophalangeal joint. When writing the orthotic prescription, we use a minimum cast fill and several degrees of inversion in the positive cast, so the orthosis conforms closely to the arch in order to allow that first ray to plantar flex. If the rearfoot is everted, we prescribe a device with a deeper heel cup and a medial heel skive to prevent further eversion,” he told LER.
“In younger children, I am more likely to prescribe a prefabricated orthosis that offers these features [deep heel cup, medial skive, forefoot valgus correction, and a fairly high arch], because children grow out of them quickly and they can become prohibitively expensive. Adolescents’ custom orthotics are likely to last for several years.”
Pain is the most common reason for surgical intervention in JHV, with progression of deformity another major factor to consider, Coughlin reported.
“On the other hand, we sometimes wait until a patient is a bit older to perform surgery,” he said. “It is not imperative that growth lines be closed, but surgery must be carefully performed to avoid injury to the growth plate.”
Several surgical procedures have been shown to successfully correct JHV, but as Coughlin and Shakked noted, concerns remain about performing orthopedic surgery in skeletally immature patients.
Shakked clarified that postsurgical therapy depends on the type of surgery performed.
“Aggressive range-of-motion activities should be minimized if an osteotomy is done to allow the osteotomy site to heal, which usually takes about six to eight weeks,” she said. “The surgeon may apply a bandage with a toe spica tape splint to keep the soft tissues stretched on the lateral side of the first MTP joint. Stretching activities of these ligaments and strengthening the abductor hallucis can be helpful postoperatively. After the bone has healed, surgeons may recommend range-of-motion activities of the hallux to prevent stiffness and regain preoperative range of motion.”
Physical therapy after any mode of JHV surgery may require extra measures to protect the surgical site and the rehabilitation of posture and gait.
In an earlier LER article exploring physical therapy after bunionectomy in adults, Clarke D. Brown, PT, DPT, OCS, ATC, who is in private practice in Macedon, NY, and is president of the American Physical Therapy Association’s foot and ankle special interest group, noted that postsurgical physical therapy should extend well above the ankle, and protocols must be adapted for individual patients (see “Beyond bunionectomy: The role of physical therapy,” August 2010, page 18). He further advised unique factors to consider when evaluating children who have undergone osteotomy for JHV.
“Young adults can be impetuous and impatient. If their surgery restores weight-bearing activity or relieves pain, these patients may push weight bearing by standing or walking on the surgical side earlier than is appropriate,” Brown said.
“Great attention should be paid to making sure surgical sites are well protected, proximally and distally. Younger children will often retain gait and movement deviations learned during painful periods. Many will continue to needlessly limp or substitute during gait, because their motor patterns were chronically changed. It is often difficult to restore normal movement even when pain and mobility are corrected,” he cautioned.
Further studies by Kinz’s team in Austria will explore the effects of intervention programs that seek to ensure correctly fitting shoes and assess whether hallux valgus is reversible after changing footwear habits.
Coughlin led a preoperative study of demographics, etiology, and radiographic findings in adults with moderate to severe hallux valgus deformities and found that 34% of patients implicated constricting shoes or occupation as causes of their bunions.16 However, nearly a quarter of participants had developed the deformity at age 20 years or younger. Family history, female gender, a long first metatarsal, and an oval or curved metatarsophalangeal joint articular surface were common findings.
Clearly, more research is needed to identify the role of poorly fitting footwear and its causative or associative function in the early development of JHV, but the persistent inability of children to distinguish poorly fitting from properly fitting shoes reported in the Austrian studies is a critical observation.
“These studies are a reminder that any of us who treat children’s feet should take the opportunity to educate parents about proper fit,” Huppin said. “Children’s feet are more pliable than adults’. While shoe length certainly is important, we also need to make sure children’s shoes are wide enough for their toes and are not applying external medial or lateral force.”
Christina Hall Nettles is a freelance writer based in Monroeville, AL.
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