Background
Spina bifida (SB) is a congenital anomaly of the central nervous system and is caused by a neural tube defect during early fetal development [
1]. Individuals with SB display a wide range of clinical features depending on the level of the neurological lesion, such as neurogenic bladder and/or bowel, hydrocephalus, cognitive impairment, sensory and motor dysfunction in the lower extremities, and orthopedic deformities, including foot deformity, scoliosis, and hip dislocation [
1]. Hence, a multidisciplinary approach, which includes neurosurgery, urology, and orthopedic surgery, is essential for the overall management of these children [
1]. Regular check-ups are required in children with SB as they grow because they are at risk of recurrence of spinal cord adhesions [
2] and neurological complications, such as tethered spinal cord syndrome [
3]. Given that spinal nerve damage is irreversible, efforts to maintain an optimal level of neurological function are required for the rest of the life of individuals with SB [
4], and they need comprehensive long-term follow-up for chronic conditions.
The clinical characteristics of SB in the Korean population tend to be at the low-lumbar and sacral levels [
5], and many individuals with SB which clinically mild severity wherein independently walking is possible without a wheelchair or crutches [
6]. Reportedly, only 2.3% of Korean individuals with SB use a wheelchair [
6]. However, it has also been reported that 33.7% of young Korean adults with SB have foot deformities, and 23.2% have lower limb weakness [
5]. People with SB lesions at the low-lumbar or sacral levels generally develop calcaneus deformities [
2]. Pes calcaneus can often cause skin breakdown resulting from weight bearing only on the calcaneus, without weight bearing on the forefoot [
7,
8]. Foot deformities also affect gait, and prolonged gait imbalance can cause hip dislocation, rotation of the knee joint, and scoliosis [
2,
4]. Furthermore, foot deformity can be congenital or develop over time due to muscle imbalance during growth [
2,
8]. Therefore, regular orthopedic follow-up and appropriate management, including orthosis or corrective surgery, are necessary for children with SB.
Orthopedic outcome assessment has mainly been performed using anatomical and functional evaluation methods, such as physical exam, radiography, pedobarography, and computerized gait analysis [
2]. In particular, radiography is used to evaluate changes in children’ orthopedic outcomes, and there are many reports of radiological improvement in outcomes after orthopedic management [
9,
10]. When evaluating changes in orthopedic conditions or actual gait improvements, pedobarography and gait analysis can be useful to complement radiography, which only shows correction from a static position [
8]. Although these objective diagnostic tests can adequately explain anatomical and functional changes, they do not reflect how orthopedic deformities and gait affect daily life and how the effects of orthopedic management influence health-related quality of life (HRQoL) from the perspective of children with SB [
11,
12]. Recently, it has been recommended to measure the effects of therapeutic interventions with both objective physical and functional outcomes and subjective HRQoL indicators [
12,
13].
However, studies investigating HRQoL in children with SB tended to focus on bladder and/or bowel dysfunction including incontinence [
6,
14,
15], and there is limited information on HRQoL related to orthopedic problems. It can be surprising to the attending orthopedist that musculoskeletal problems or deformities that seem quite impressive are far down the list of the patient’s priorities. Furthermore, it has been suggested that further studies address the impact of orthopedic problems and mobility on HRQoL [
2]. Therefore, in this study, we aimed to examine the relationship between foot deformity and HRQoL in children with SB.
Methods
Aim
This study aimed to examine the relationship between foot deformity and health-related quality of life (HRQoL) among independently ambulating children with SB.
Study design and participants
This cross-sectional study included children with SB who presented for regular follow-up at the outpatient clinic in the pediatric orthopedic surgery department of the Severance Children’s Hospital from March 2020 to July 2021. Children were enrolled if they were aged 7–18 years. The following exclusion criteria were applied: inability to walk independently (n = 2) and less than two years since corrective surgery (n = 6). The orthopedic surgeon briefly discussed the study with each child and their parents. A research assistant subsequently provided more detailed information for children and parents interested in the study. The survey questionnaire included questions addressing clinical characteristics, the impact of the ankle and foot on children’s daily life and HRQoL.
The sample size required for this study was calculated using G*Power 3.1.9.7; one-way ANOVA; two-sided; effect size = 0.25 to 0.40 (medium to large); α = 0.05; power (1-β) = 0.80; four groups. The sample size was calculated to range from 76 to 180. Since there was no previous study analyzing the differences in HRQoL according to foot deformity in children with SB, we reviewed previous studies that analyzed HRQoL differences in children with SB according to bowel management methods, SB lesion, or incontinence; the number of sample size of each study was 159, 173, and 298 children, respectively [
6,
15,
16]. Although the sample size in this study was smaller than that of previous studies, we did our best and aimed to recruit all children who visited the hospital during the study period and met the eligibility criteria. Finally, 93 children were involved in the study. The study was approved by Yonsei University Health System, Severance Hospital, Institutional Review Board (No. 4-2019-1248). All methods were carried out in accordance with the Declaration of Helsinki. Written informed consent was obtained from all children and their parents.
Measures
The impact of foot and ankle conditions was measured using the Oxford Ankle Foot Questionnaire (OxAFQ) [
17]. OxAFQ has been developed and validated to measure the impact of foot and ankle conditions on aspects of life that are considered important for children [
17,
18]. The questionnaire consists of 15 items rated on a 5-point Likert scale (0, always; 1, very often; 2, sometimes; 3, rarely; and 4, never), the first 14 of which are used to calculate subscale scores, and comprises three subscales (physical, 6 items; school and play, 4 items; emotional, 4 items; and footwear as an additional item). The scores for the three subscales are reported separately; therefore, there is no total score. Subscale scores were calculated by deriving the sum of each subscale and subsequently dividing it by the subscale’s maximum value; these scores were subsequently transformed to a percentage (0–100) scale to aid interpretation. A higher score corresponds to better function. The final item, namely, item 15 (“Has your foot or ankle stopped you from wearing any shoes you wanted to wear?”), was added to reflect the concern of many children that they cannot wear the footwear they like. Although this issue is important to children, it psychometrically does not fit into any of the subscales; this final item has been reported separately [
17]. Cronbach’s alpha was 0.96 in this part of the study.
The Pediatric Outcomes Data Collection Instrument (PODCI) is used to measure the overall musculoskeletal function and HRQoL in children aged 2–18 years with orthopedic conditions, focusing especially on those that are moderate to severe [
19]. The Korean version of the PODCI [
20] was used to measure HRQoL. The PODCI subscales comprise the following: [
1] upper extremity functioning, [
2] transfer and basic mobility, [
3] sports and physical functioning, [
4] comfort and pain, [
5] happiness with physical functioning, and [
6] global functioning [
17]. Global functioning was calculated as the average of the scores of the four subscales except for happiness. The scoring system used for the questionnaire was established using an algorithm designed specifically for use by the research team. Each subscale score was calculated individually and standardized (range, 0–100). A higher standardized score indicated better condition. Cronbach’s alpha was 0.907 in this study.
Data collection
The research assistant screened the list of children with SB who met the eligibility criteria and contacted them and/or their parents by telephone to explain the purpose of the study and its procedures. Children who were willing to participate in this study were provided with a copy of the survey by the research assistant when they visited the clinic for follow-up. Before they completed the survey, the researcher explained it to them in detail. We obtained the OxAFQ and PODCI questionnaires; additionally, demographic and clinical information, including sex, age, diagnosis, neurological lesion, functional classification, type of orthopedic deformity (hip, spine, knee, and foot), presence of a ventriculoperitoneal (V-P) shunt, type and date of orthopedic surgery, voiding and defecation methods, and urinary/fecal incontinence, were obtained from the electronic medical records by the research assistants.
A pediatric orthopedic surgeon with 21 years of experience described the spine, hip, knee, or foot deformities in the electronic medical record during the physical examination. A pediatric orthopedic surgeon with at least 15 years of experience categorized the eight types of foot deformity (equinocavovarus, cavovarus, calcaneus, planovalgus, calcaneocavovarus, calcaneocavus, equinus, and vertical talus) and classified them into four types of foot deformity (calcaneus, equinus, cavus, and planus) to analyze the differences in HRQoL according to foot deformity types.
Statistical analyses
Statistical analyses were performed using SPSS version 26.0 (IBM Corp., Armonk, NY, USA), and values of p < 0.05 were considered statistically significant in this study. The clinical characteristics of the study population were examined according to foot deformity status using descriptive statistics and Pearson’s chi-squared test. Additionally, the mean difference in OxAFQ and PODCI scores was analyzed using an independent t-test, one-way ANOVA, Kruskal–Wallis one-way analysis of variance based on the clinical characteristics, including foot deformity status.
Discussion
We investigated the orthopedic characteristics of children aged 7–18 years with SB focusing on foot deformities. The prevalence of foot deformity was higher than that of other orthopedic deformities, such as spine, hip, and knee, and children with foot deformities had a high proportion of bladder or bowel dysfunction and SB lesions at high-sacral or low-lumbar levels. Children with bilateral foot deformity, equinus foot deformity type, or mixed deformity types reported lower HRQoL. These findings suggest that, even children with clinically mild severity of sacral-level SB lesions, may have poor HRQoL if they have specific foot deformities combined with other clinical problems. The study highlights the need to pay attention to orthopedic characteristics that have been relatively overlooked when assessing HRQoL in children with SB.
The most common type of the foot deformity was pes calcaneus. This is consistent with previous findings that individuals with sacral-level SB lesions have a high incidence of pes calcaneus deformities [
13]. Foot deformity is associated with the level of SB lesions, with a higher incidence of calcaneus observed in children with lower levels of SB lesions [
2,
13]. This results from inadequate innervation in the antagonistic muscle groups, such as the soleus and gastrocnemius, which work against the tibial muscles innervated from the lumbar and sacral regions. Furthermore, insufficient innervation of tibial muscles can result in overactivity of the opposing muscles and lead to foot deformities [
2,
10]. Pes calcaneal deformity typically results in the breakdown of the skin on the heel and osteomyelitis [
2,
8]; therefore, careful monitoring for skin integrity is essential.
Most Korean children with SB can walk independently since their lesions at the sacral level, which are known to not significantly affect ambulation status. However, previous studies of HRQoL in children with SB have identified that factors such as urinary and fecal incontinence requiring CIC or the use of enemas negatively affect HRQoL [
6,
15]. In this study, the incidence of bladder or bowel dysfunctions varied according to the presence of foot deformity. Individuals with SB need to be evaluated and managed very carefully because of their multiple comorbidities [
2] and an individualized approach is needed to establish an appropriate care plan.
Children with foot deformities tended to have lower mean scores in the footwear subscale of OxAFQ-C, regardless of foot deformity type. Although not statistically significant due to very large standard deviation, these results suggest that children with SB with foot deformities can feel notably limited in choosing the shoes they want. A study on the experience of young adults with SB in Korea found that wearing orthosis and lower limb appearance had a negative effect on body image and psychosocial well-being [
22,
23]. This suggests that concerns about appearance and body image related to lower extremity deformities or orthosis use may be as important as mobility problems for children with SB.
Children with foot deformity had a significantly greater mean differences in PODCI scores related to happiness with physical condition compared to physical function when compared to children with normal feet, indicating a potential disparity between perceived physical function and the associated satisfaction. Furthermore, the large standard deviation in the happiness with physical condition scores for children with foot deformities highlights the significance of individual variations in their subjective experiences. As such, assessing the HRQoL of children with SB requires evaluating both physical function and psychosocial well-being [
24]. These results align with the disability paradox, where individuals with mild SB tend to compare themselves to healthy peers, resulting in frustration and disappointment [
25,
26]. Therefore, high-functioning children with SB in Korea may require attention and support to address their psychosocial vulnerabilities.
This study has some limitations. First, it is necessary to measure improvement in HRQoL according to changes in foot deformity and lower extremity function before and at least 2 years after corrective surgery in the same children; however, we could not evaluate this in our study because of its cross-sectional design. In the future, a longitudinal study with a long-term follow-up is needed. Second, children in the study had a higher percentage of lipomyelomeningocele and were highly functioning, unlike the clinical distribution of SB types in the West [
27]. Because prenatal screenings are more frequently performed in South Korea, fetal malformations are more easily detected [
6]. Unfortunately, fetuses with myelomeningocele are often terminated, which is not legal but often occurs [
6]. Therefore, our findings are difficult to generalize for adolescents with SB with lower functioning. Lastly, neurogenic bladder or bowel is a well-known factor affecting HRQoL and an important confounding factor in this study. To better study the association between foot deformity and HRQoL, it would be appropriate to include only individuals without bladder or bowel dysfunction, but this was not possible in this study because of the small sample size. Therefore, the results of this study should be interpreted with caution, considering that bladder or bowel dysfunction was not adjusted for in the analyses.
Conclusions
The goal of orthopedic treatment in children with SB is to maintain optimal musculoskeletal status as far as possible for a given individual’s neurological function. In this study, we found that foot deformity is related to poorer HRQoL in children with SB. However, not all children have the same orthopedic needs. Our results suggest that children with foot deformities, particularly those with bilateral foot deformities, equinus deformities, or mixed deformities, have a lower perceived HRQoL. Regarding the HRQoL of children with SB, we identified the need to assess orthopedic characteristics that have not been a concern. Pediatric orthopedists are required to assess the special needs or difficulties of children with SB and take them in consideration when devising the treatment plan. Further studies involving larger populations are needed to explore the differences in HRQoL according to the type of deformity. Therefore, it is not possible to conclude about the need to correct certain deformities, and treatments should be individualized to ensure a plantigrade braceable foot.
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