Abstract
Background
Flatfoot is common among children. Symptomatic flexible flatfoot is one of the various types which needs treatment. Wearing insoles is considered one of the conservative therapies, but its effects are still uncertain. This study aims to provide evidence for the efficacy of insoles treatment among school-aged children with symptomatic flexible flatfoot.
Methods
Patient who were Children who were diagnosed with symptomatic flexible flatfoot and received insoles treatment in authors’ institute were retrospectively included. Their ages, body mass index, pain positions, pain frequency, valgus angle, arch index and visual analogue scale (VAS) score were collected before and after insole treatment.
Results
A total of 32 children were included in this study. The results showed that wearing insoles for 2 years caused a significant improvement in pain frequency, valgus angle, arch index and VAS score.
Conclusions
This study indicated that pediatric symptomatic flexible flatfoot could be relieved by wearing insoles for 2 years. Insole treatment might be a workable option for pediatric symptomatic flexible flatfoot in children older than 6 years old.
Keywords: Child, Flatfoot, Insoles, Symptomatic flexible flatfoot
Introduction
Pediatric flatfoot is a common condition, and the prevalence is up to 97% in children within 2 years of age. Severe flatfoot could cause pain and disability, affecting patients’ daily lives [1]. An anatomical feature of flatfoot is the disappearance of the medial longitudinal arch, which might cause gait change [2]. Flexible flatfoot and rigid flatfoot are two types of flatfoot deformity [3]. Flexible flatfoot or physiological flatfoot is the most common variant, where the medial longitudinal arch can be seen upon dorsiflexion of the big toe or tiptoeing but disappears upon standing with weight-bearing [4].
Treatments for flexible flatfoot depend on the clinical symptoms. Intervention is necessary when patients have pain or tend to develop disability. Some researchers have reported the efficacy of insoles for flatfoot treatment with improvement in foot arch angle, which was confirmed by radiographic measurement [5]. However, some researchers reported uncertainty about the efficacy of the insoles [6].
A limited number of studies reported the effects of insoles treatment over 6 months among school-aged children with pediatric symptomatic flatfoot [7,8]. This study aims to report the mid-term clinical results and show the efficacy of insoles treatment for 2 years.
Materials and Methods
From July 2016 to June 2018, children diagnosed with symptomatic flexible flatfoot were identified retrospectively from the database of the authors’ institute. The inclusion criteria were: (a) children aged 6 years or more, (b) treated with insoles, and (c) having a follow-up of at least 24 months. Exclusion criteria were: (a) children with pathological flatfoot, (b) having inadequate medical or physiotherapy records, and (c) follow-up period < 2 years or lost the follow-up. All children were diagnosed based on physical examination and measurement of the arch index. The children and their caregivers were informed that the children needed to receive insole treatment for at least 8 h per day. Their guardians were responsible for monitoring and recording the wearing time every day. The Ethics Committee of the authors’ hospital approved the study. Written informed consents were obtained from the legal guardians.
After obtaining the feet model with plaster and modifying its shape, the insoles were customized and prepared with polyurethane components. The demographic data, including age, gender, BMI, and location of pain, was collected. The standard for overweight was from a report by Cheng-Ye Ji [9]. The clinical data, including frequency of pain, valgus angle, arch index (AI) of their feet and visual analogue scale (VAS), were collected before and after a 2-year follow-up. Frequency of pain and VAS were investigated to reflect the severity of flatfoot symptoms. AI and valgus angle were used as parameters to evaluate the objective evaluation of plantar pressure. AI is the area ratio of the middle third of the footprint to the entire footprint area (excluding the toes) [10]. The normal range is from 0.21 to 0.26, while arch index > 0.26 means flatfoot [11]. Valgus angle was measured based on the research of Chang C et al. [12]. Its normal value is from 0 to 5 degrees and over 5 degrees can be considered valgus. VAS is a highly sensitive and simple tool to evaluate the degree of pain, which is suitable for children over 6 years old [13]. In VAS, 0 represents painless and 10 represents the most severe pain sensation [13].
Customized insoles were made based on individual information of patients, including arch index, gait analysis and valgus angle. The feet model was obtained with plaster, and its shape was modified. Then the insoles were formed with components made of polyurethane. Each part was designed to have a specific effect function (Fig. 1). A pair of orthopedic insoles were made through molding and polishing. After six to nine months, insoles were changed according to the feet growth.
Fig. 1.
Insoles (A) and the valgus angle change before (B) and after (C) wearing
SPSS 25.0 was used to analyze the data. Means and standard deviations were calculated to describe the results in tables. Paired t test was utilized. P value < 0.05 was the indication of statistical significance.
Results
Thirty-two children (18 boys and 14 girls) were enrolled in this study. All the children had bilateral planovalgus deformity. The average age of boys was 9.17 ± 1.29 and that of girls was 9.57 ± 1.55, ranging from 7 to 12 years. Among the participants, 25 children (15 boys and 10 girls) had normal BMI, while seven children (3 boys and 4 girls) were overweight. Most overweight children had pain in the plantar arch, and only one of them had pain in the plantar heel (Fig. 2A). Among the children with normal BMI, the counts for pain in the plantar arch, plantar heel, Achilles tendon and ankle joint were similar (Fig. 2A). The distribution of the pain positions based on gender was obtained. It showed that nine boys and six girls had pain in the arch; Four boys and three girls had pain in the plantar heel; Two boys and two girls had pain in the Achilles tendon; Three boys and three girls had pain in the ankle joint (Fig. 2B).
Fig. 2.
A Distribution of pain positions of each subject according to BMI. Red bars represent overweight children and blue bars stand for children with normal BMI. B Distribution of pain positions based on gender. Red bars represent female and blue bars stand for male
After 2 years of treatment with insoles, all the children showed significant improvement in pain frequency, VAS, AI and valgus angle (P < 0.001) (Table 1). The post-treatment symptom parameters showed positive changes compared with pre-treatment in male and female (P < 0.05). Parameters between different genders showed no significance before and after treatment (P > 0.05) (Tables 2, 3, 4 and 5). In addition, the improvement between overweight and normal-weight children was statistically significant (P < 0.05). Before treatment, pain frequency, VAS, AI, and valgus angle of overweight children were higher than normal-weight children (P < 0.05). After the treatment, the pain frequency of normal-weight children was 2.04 ± 1.81, while the same indicator in overweight children was 4.00 ± 1.20. Similarly, the VAS score for normal-weight children was 0.76 ± 0.60 and that for overweight children was 1.57 ± 0.53. Moreover, AI of normal-weight children was 0.25 ± 0.01, which was in the normal range, while AI of overweight children was 0.27 ± 0.01; and valgus angle was 4.54 ± 0.50 in normal-weight children and 5.36 ± 0.24 in overweight children (Tables 2, 3, 4 and 5). A typical case of improvement was shown in Fig. 3.
Table 1.
General comparison of parameters
| Parameters | Before | After | P |
|---|---|---|---|
| Pain frequency | 21.34 ± 2.22 | 2.53 ± 1.87 | < 0.0001 |
| VAS | 2.63 ± 0.87 | 0.94 ± 0.67 | < 0.0001 |
| AI | 0.32 ± 0.02 | 0.25 ± 0.01 | < 0.0001 |
| Valgus angle | 5.66 ± 0.78 | 4.72 ± 0.57 | < 0.0001 |
Table 2.
Comparison of pain frequency based on gender and BMI
| Pain frequency | Ρ | ||
|---|---|---|---|
| Before | After | ||
| Gender | |||
| Male | 21.00 ± 2.22 | 2.56 ± 2.04 | < 0.0001 |
| Female | 21.79 ± 2.22 | 2.50 ± 1.70 | < 0.0001 |
| Ρ | 0.3294 | 0.935 | |
| BMI | |||
| Normal | 20.75. ± 2.07 | 2.04 ± 1.81 | < 0.0001 |
| Overweight | 23.13 ± 1.73 | 4.00 ± 1.20 | < 0.0001 |
| Ρ | 0.0066 | 0.0078 | |
Table 3.
Comparison of VAS based on gender and BMI
| VAS | Ρ | ||
|---|---|---|---|
| Before | After | ||
| Gender | |||
| Male | 2.61 ± 0.78 | 0.89 ± 0.68 | < 0.0001 |
| Female | 2.64 ± 1.01 | 1.00 ± 0.68 | < 0.0001 |
| Ρ | 0.9205 | 0.6488 | |
| BMI | |||
| Normal | 2.36 ± 0.76 | 0.76 ± 0.60 | < 0.0001 |
| Overweight | 3.57 ± 0.53 | 1.57 ± 0.53 | < 0.0001 |
| Ρ | 0.0004 | 0.0029 | |
Table 4.
Comparison of AI based on gender and BMI
| AI | Ρ | ||
|---|---|---|---|
| Before | After | ||
| Gender | |||
| Male | 0.32 ± 0.03 | 0.25 ± 0.01 | < 0.0001 |
| Female | 0.33 ± 0.02 | 0.25 ± 0.01 | < 0.0001 |
| Ρ | 0.734 | 0.5093 | |
| BMI | |||
| Normal | 0.31 ± 0.02 | 0.25 ± 0.01 | < 0.0001 |
| Overweight | 0.36 ± 0.02 | 0.27 ± 0.01 | < 0.0001 |
| Ρ | < 0.0001 | < 0.0001 | |
Table 5.
Comparison of valgus angle based on gender and BMI
| Valgus angle | Ρ | ||
|---|---|---|---|
| Before | After | ||
| Gender | |||
| Male | 5.61 ± 0.80 | 4.64 ± 0.51 | < 0.0001 |
| Female | 5.71 ± 0.78 | 4.82 ± 0.64 | < 0.0001 |
| Ρ | 0.7159 | 0.375 | |
| BMI | |||
| Normal | 5.40 ± 0.56 | 4.54 ± 0.50 | < 0.0001 |
| Overweight | 6.57 ± 0.79 | 5.36 ± 0.24 | 0.0023 |
| Ρ | 0.0001 | 0.0002 | |
Fig. 3.
Improvement of a 7-year old boy with normal BMI. A and C showed the footprints and valgus angle before treatment. B and D presented the improvement after treatment.
Discussion
The pathogenesis of flatfoot is complex and has two mainstream opinions. One is the Osseo-ligamentous structure deficiency, and the other is the reduction of foot muscle strength [16]. In addition, some literature reported that the weight and gender of the children were also related to flatfoot [17, 18]. A recent systematic review also indicated that childhood obesity or overweight might cause flatfoot and change in posture [19]. Being overweight or obese might be a risk factor for flatfoot because it increases the weight-loading [20]. It also flattened the longitudinal arch [21], which might explain that most overweight children in this study had pain in the plantar arch. There was a difference in the improvement of parameters between normal and overweight children in this study before and after the intervention. Symptoms were more severe in overweight children than normal children before the treatment. Overweight children had higher VAS score, AI, and valgus angle. Parameters of children with normal weight showed better improvement than overweight children (Tables 2, 3, 4 and 5).
Pain in symptomatic flatfoot may be due to the lack of inversion in the hindfoot, which results in a loss of lever for propulsion. The problems may contribute to foot pain and fatigue in gait [4]. Treatments for pediatric symptomatic flexible flatfoot include conservative or surgical interventions. Conservative interventions include insoles or other kinds of orthoses, activity modification and serial castings [2, 22]. Some researchers reported the therapeutic effect of insole treatment in pediatric flexible flatfoot. A randomized controlled trial by Ru-Lan Hsieh [23] demonstrated that customized arch support insoles improved pain and physical function in patients. The purpose of using insoles is to re-create a lever, sustaining the shape of the arch and distributing the plantar pressure [14]. An observational cohort study conducted by Chen et al. proved that insoles could reduce the risk of the prominent navicular bone and relieve symptoms in preschool-aged children [15]. In this study, the AI and valgus angle were closed to or within the normal range. VAS and frequency of pain decreased after the treatment. These results indicated that symptomatic pain was relieved by insoles treatment.
On the other hand, some studies did not provide the acceptable therapeutic effect of the insole. Wenger et al. [24] demonstrated that among 131 preschool children, wearing insoles for 3 years did not impact the course of pediatric flexible flatfoot. Kanatl et al. [25] also indicated that insoles were ineffective in developing foot arches. These studies demonstrated that insole usage for pediatric flexible flatfoot should be limited. Moreover, both Kanatl and Wenger's long-term follow-up study of children aged 1–6 years concluded no statistically significant difference between control and treatment groups in flatfoot development. These studies did not evaluate the treatment effects of insoles in children over 6 years old. The foot arch still has much potential for development before the age of 6. Flatfoot in this period should be considered physiological, which could be spontaneously corrected during the children’s grow up [26]. Therefore, flatfoot might not be an indication for insole treatment before 6 years old. This study mainly included children over 6 years old, which could relatively decrease the influence of the natural development of foot arch. After 2 years of follow-up, VAS, AI and valgus angle were significantly improved in all children. After wearing the insole for 2 years, the AI was close to or in the normal range, which showed a positive effect on the physiological structure and plantar pressure for school-age children with symptomatic flexible flatfoot.
There are some limitations to this study, such as small sample size. To clarify the relationship between obesity and flatfoot, the number of overweight children should be increased. The influence of growth might play a role in the development of flatfoot and could not be excluded in this study. In addition, a 2-year follow-up period might not clarify the exact effect of insoles. Further study with larger sample size and longer follow-up is recommended in the future.
Conclusions
This study indicated that wearing insoles is a workable option for pediatric symptomatic flexible flatfoot in school-age children. The symptom could be relieved by wearing insoles for 2 years.
Declarations
Conflict of Interest
There is not any conflict of interest or industry support for the study. All the authors declared that they have no conflict of interest.
Ethical Approval
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The Ethics Committee of Tongji Medical College, Huazhong University of Science and Technology (IORG No: IORG0003571) gave final approval for this study. Although the data were collected anonymized and centrally, all guardians of patients signed written informed consent for participate.
Informed Consent
All guardians of patients signed written informed consent for publication.
Footnotes
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Jin Li and Zimo Yang contributed equally to this work.
Contributor Information
Jin Li, Email: lijin2003@hust.edu.cn.
Zimo Yang, Email: yangzimo808@hust.edu.cn.
Saroj Rai, Email: mesaroz@outlook.com.
Xiangrui Li, Email: lixiangrui@hust.edu.cn.
Guoyong Jiang, Email: jianggy@hust.edu.cn.
Xiaofei Pan, Email: crazyjuanjuan@hotmail.com.
Xin Tang, Email: dr_xintang@hust.edu.cn.
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