Club foot

Congenital talipes equinovarus: A literature review

Congenital talipes equinovarus (CTEV) is a congenital disability characterized by leg deformities in the cavus, adducts, varus, and equinus. The etiology of CTEV is poorly understood, despite its incidence ranging from 0.76 to 3.49 cases per 1000 live births in Indonesia. CTEV involves the fixation of the foot in the adducts, varus, and equinus with concurrent soft tissue anomalies. Despite advances in treatment, disability often persists. Theoretical models have been proposed for neurological, vascular, connective tissue, bone, and muscular causes; however, the currently available data suggests that mild cases are associated with intrauterine position. CTEV's etiology appears to involve a hereditary component, as its prevalence varies by ethnic group. Genetic factors have been identified in 24–50% of cases, depending on the community studied. Based on a complex segregation analysis, the most plausible inheritance pattern is a single large-effect gene interacting with a polygenic background.

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CTEV is a congenital disability characterized by leg deformities in the cavus, adducts, varus, and equinus.

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In Indonesia, its incidence ranges from 0.76 to 3.49 cases per 1000 live births.

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Genetic factors have been identified in 24–50% of cases, depending on the community studied.

Clubfoot pathology in fetus and pathogenesis. A new pathogenetic theory based on pathology, imaging findings and biomechanics-a narrative review

Several studies have described the pathology of idiopathic congenital clubfoot (ICCF) in fetus. Numerous pathogenetic theories have been postulated on ICCF, but many of them lack any objective evidence. Pathologic studies in fetus together with MRI studies in patients with ICCF seem to favor the theory of a muscular imbalance of the foot activators during fetal growth as the main pathogenetic factor of ICCF. Our objectives were: (I) To support the theory of muscular imbalance as the primary pathogenetic factor of ICCF; (II) To clarify why atrophy and shortening affect the activator muscles of the foot unevenly, as reported by literature. A literature search based on MEDLINE and the COCHRANE database was performed to identify all published studies from 1929 to 2020 which report ICCF pathology in fetus, its etiopathogenesis, and imaging and biomechanical studies showing how the basic pathology may be addressed by Ponseti treatment. A manual search was also performed of the references cited in studies, reviews, and university libraries. Altered size, shape and articular relationships of the tarsal bones, and uneven atrophy and shortening of the leg muscles together with capsule and ligament abnormalities were the main pathologic findings reported in fetus with ICCF. Regarding ICCF pathogenesis, the main debate is between the advocators of a primitive blastemal defect of the tarsal bones leading to the skeletal abnormalities and those who hold that the latter are secondary to a deforming force generated by the soft tissues. Imaging studies have shown that the Ponseti method is able to address the skeletal abnormalities, the correction of which is maintained until adulthood, whereas leg muscle atrophy is not improved but tends to worsen with growth. Preliminary histochemical studies of the soleus-Achilles tendon junction have shown a decrease of the growth factors and the presence of myostatin, both down-regulators of muscle growth in patients with ICCF. The authors postulate that a defect of both the radial and the longitudinal growth unevenly affecting the leg muscles with a consequent imbalance of the foot activators might be the main pathogenetic factor of ICCF. Further studies are needed to confirm this theory.

Association Between TPM1 Gene Polymorphisms and Idiopathic Congenital Talipes Equinovarus Risk in a Chinese Population

Background: Idiopathic congenital talipes equinovarus (ICTEV) is one of the most common congenital deformities of children, and dysplasia of the striated muscle may be one of the causes of ICTEV. Previous studies have shown that polymorphisms of the rs4075583 SNP in the tropomyosin gene 1 (TPM1) were associated with ICTEV in Caucasian children. However, there are no studies investigating the correlations of TPM gene polymorphisms with the risk of ICTEV in Chinese children. Methods: We conducted a case-control study, including 430 children with ICTEV and 891 ICTEV-free children. We explored the potential correlations of three TPM gene polymorphisms (TPM1/rs4075583 G>A, tropomyosin gene 2 (TPM2)/rs2145925 C>T, and TPM2/rs2025126 G>A) with ICTEV risk. The three single nucleotide polymorphisms (SNPs) were genotyped using a TaqMan method. We calculated the odds ratios (ORs) and adjusted ORs and their 95% confidence intervals (CIs) to explore the associations between these selected SNP polymorphisms and ICTEV. Results: TPM1 rs4075583 A was found to be associated with an increased ICTEV risk (AA vs. GG: adjusted OR = 1.70, 95% CI = 1.15-2.49, p = 0.007; and GG/GA vs. AA: adjusted OR = 1.62, 95% CI = 1.14-2.31, p = 0.0071) after adjusting for age and sex. In addition, a risk effect of rs4075583 GA/AA with ICETV was observed for patients with affected right feet (adjusted OR = 1.62, 95% CI = 1.10-2.39, p = 0.014) in the stratified analysis. However, there were no significant differences in the risk for ICTEV associated with the rs2145925 and rs2025126 polymorphisms. Conclusion: These results indicate that the TPM1 rs4075583 G > A polymorphism is associated with ICTEV risk in a southern Chinese population; however, this finding needs to be confirmed in larger studies and through mechanistic studies.

Plantar pressures in identical and non-identical twins

Identifying environmental risk factors for musculoskeletal disorders is challenging due to the number of potential confounders. Twins are of particular interest for researchers interested in studying these types of problems due to their inherent control for the influence of genetic factors. In twin studies, this population can allow environmental risk factors to be more easily identified, and this type of study design may allow the role of biomechanics in injury and disease to be further explored. At present, it is unclear if foot function displays more similarity between certain types of twins. In this study, we hypothesized that the plantar pressures of monozygotic (identical) twins would be more similar between pairs than dizygotic (non-identical) twins. We measured static and dynamic plantar pressures from five pairs of each twin type. Statistical parametric modeling was used to compare pressure distributions at the sensor level. For >80% of stance phase, the pixel level analysis indicated that monozygotic twins had less variation in plantar pressure between pairs. The average z-statistic across the entire trial was 0.88 for the monozygotic group and 1.13 for the dizygotic group. In this study we provide evidence of greater similarity of plantar pressures in monozygotic twin pairs compared to dizygotic twins. This finding supports the use of co-twin studies investigating potentially modifiable environmental and biomechanical risk factors for musculoskeletal conditions that affect the foot and ankle.

Birth Anomalies in Monozygotic and Dizygotic Twins: Results From the California Twin Registry

Background

Inherited factors and maternal behaviors are thought to play an important role in the etiology of several congenital malformations. Twin studies can offer additional evidence regarding the contribution of genetic and lifestyle factors to common birth anomalies, but few large-scale studies have been reported.

Methods

We included data from twins (20,803 pairs) from the population-based California Twin Program. We compared concordance in monozygotic (MZ) to dizygotic (DZ) twins for the following birth anomalies: clubfoot, oral cleft, spina bifida, muscular dystrophy, deafness, cerebral palsy, strabismus, and congenital heart defects. Each birth anomaly was also examined for the associations with birth characteristics (birthweight and birth order) and parental exposures (age, smoking, and parental education).

Results

The overall prevalence of any selected birth anomaly in California twins was 38 per 1,000 persons, with a slightly decreasing trend from 1957–1982. For pairwise concordance in 6,752 MZ and 7,326 like-sex DZ twin pairs, high MZ:DZ concordance ratios were observed for clubfoot (CR 5.91; P = 0.043) and strabismus (CR 2.52; P = 0.001). Among the total 20,803 pairs, parental smoking was significantly associated with risk of spina bifida (OR 3.48; 95% CI, 1.48–8.18) and strabismus (OR 1.61; 95% CI, 1.28–2.03). A significant quadratic trend of increasing risk for clubfoot, spina bifida, and strabismus was found when examining whether father smoked, mother smoked, or both parents smoked relative to non-smoking parents (P = 0.029, 0.026, and 0.0005, respectively).

Conclusions

Our results provide evidence for a multifactorial etiology underlying selected birth anomalies. Further research is needed to understand the biological mechanisms.

Genetics of clubfoot; recent progress and future perspectives

Clubfoot or talipes equinovarus (TEV) is an inborn three-dimensional deformity of leg, ankle and foot. It results from structural defects of several tissues of foot and lower leg leading to abnormal positioning of foot and ankle joints. TEV can lead to long-lasting functional disability, malformation and discomfort if left untreated. Substantial progress has been achieved in the management and diagnosis of limb defects; however, not much is known about the molecular players and signalling pathways underlying TEV disorder. The homeostasis and development of the limb depends on the complex interactions between the lateral plate mesoderm cells and outer ectoderm. These complex interactions include HOX signalling and PITX1-TBX4 pathways. The susceptibility to develop TEV is determined by a number of environmental and genetic factors, although the nature and level of interplay between them remains unclear. Familial occurrence and inter and intra phenotypic variability of TEV is well documented. Variants in genes that code for contractile proteins of skeletal myofibers might play a role in the aetiology of TEV but, to date, no strong candidate genes conferring increased risk have emerged, although variants in TBX4, PITX1, HOXA, HOXC and HOXD clusters genes, NAT2 and others have been shown to be associated with TEV. The mechanisms by which variants in these genes confer risk and the nature of the physical and genetic interaction between them remains to be determined. Elucidation of genetic players and cellular pathways underlying TEV will certainly increase our understanding of the pathophysiology of this deformity.

Neonatal Abstinence Syndrome: Twins Case Series

BACKGROUND

Use or abuse of opioids and related drugs during pregnancy increases the risk of maternal and neonatal morbidities, including increased susceptibility to Neonatal Abstinence Syndrome (NAS). Severity of NAS is determined by both environmental and genetic factors, but the level of influence each one of them has in determining the severity of NAS is not fully understood. Since the incidence and severity of NAS vary a lot among susceptible infants, twin studies might give us valuable insights into understanding the relative roles of environmental and genetic factors at the onset of the disease and during its progression. Higher concordance of occurrence and severity of NAS in monozygotic twins compared to dizygotic twins would suggest a genetic role in the pathogenesis of NAS. However, comparable concordance suggests a non-genetic or an environmental basis. In this case series, we report neonatal outcomes including severity of NAS among monozygotic and dizygotic twins.

METHODS

A retrospective chart review was performed for all newborn twins who were at risk of developing NAS, were born in our institution between January 2006 and December 2014, and had a gestational age of 30 weeks or greater.

RESULTS

During the study period, we identified seven sets (total of 14 infants) of eligible twins, comprising six dizygotic and one monozygotic twins, from a total of 550 infants who were at risk of developing NAS. Among the seven sets of twins, two sets were concordant for severe NAS and required pharmacological management, three sets of twins were concordant in not having severe NAS and did not require pharmacological management, and the remaining two sets were discordant, where one of the twins required pharmacological treatment.

CONCLUSION

Five of the seven sets of twins in our study exhibited concordance and two sets showed discordance in withdrawal severity. Larger studies may help in understanding the roles of genetic and environmental factors in determining the severity of NAS.

A Twin Study of Perthes Disease

BACKGROUND

Legg-Calvé-Perthes disease (LCPD) is an idiopathic avascular necrosis of the femoral head. Its etiology is poorly understood, although previous studies have implicated low birth weight and possible genetic determinants. The aim of this study was to identify potential birth weight and genetic associations with LCPD.

METHODS

We extracted all twin pairs from the Danish Twin Registry (DTR) in which at least 1 individual had LCPD. The DTR captures every twin pair born alive in Denmark, and those with LCPD were identified by using health record linkage. Probanwise concordance was calculated to describe the likelihood that any given individual had LCPD if their co-twin was also diagnosed.

RESULTS

There were 81 twin pairs: 10 monozygotic, 51 dizygotic, and 20 unclassified (unknown zygosity [UZ]). There was no association between birth weight and being the affected co-twin. Four pairs (2 dizygotic and 2 UZ) were concordant for LCPD, which is greater than would be expected assuming no familial aggregation. There were no concordant monozygotic twin pairs. The overall probandwise concordance was 0.09 (95% confidence interval [CI]: 0.01-0.18): 0.00 for the monozygotic, 0.08 (95% CI: 0.00-0.18) for the dizygotic, and 0.18 (95% CI: 0.00-0.40) for the UZ twin pairs.

CONCLUSIONS

This study found evidence of familial clustering in LCPD but did not show a genetic component. The absolute risk that a co-twin of an affected individual will develop LCPD is low, even in the case of monozygotic twin pairs.

A new conceptual framework for investigating complex genetic disease

Some common diseases are known to have an inherited component, however, their population- and familial-incidence patterns do not conform to any known monogenic Mendelian pattern of inheritance and instead they are currently much better explained if an underlying polygenic architecture is posited. Studies that have attempted to identify the causative genetic factors have been designed on this polygenic framework, but so far the yield has been largely unsatisfactory. Based on accumulating recent observations concerning the roles of somatic mosaicism in disease, in this article a second framework which posits a single gene-two hit model which can be modulated by a mutator/anti-mutator genetic background is suggested. I discuss whether such a model can be considered a viable alternative based on current knowledge, its advantages over the current polygenic framework, and describe practical routes via which the new framework can be investigated.

Heritability of clubfoot: a twin study

INTRODUCTION

The aetiology of congenital clubfoot is unclear. Although studies on populations, families, and twins suggest a genetic component to the aetiology, other studies have identified environmental factors. The purpose of this study was to calculate heritability in order to determine to what extent genetic and/or environmental factors contribute to the aetiology of congenital clubfoot and to asses whether there was a change in the prevalence over time.

MATERIALS AND METHODS

The Odense based Danish Twin Registry is unique as it contains data on all the approximately 85,000 twin pairs born in Denmark over the last 140 years. All 46,418 twin individuals born from 1931 through 1982, who had earlier consented to contact, received a 17-page Omnibus questionnaire in the spring of 2002. Data were analysed with structural equation models to identify the best fitting aetiological model based on a balance of goodness-of-fit and parsimony and to estimate heritability.

RESULTS

We found an overall self-reported prevalence of congenital clubfoot of 0.0027 (95 % confidence interval 0.0022-0.0034). Fifty-five complete (both twins answered the question) twin pairs were identified representing 12 monozygotic, 22 same-sex dizygotic, 18 opposite-sex dizygotic, and 3 with unclassified zygosity. The model with only environmental factors (CE) was best fitting based on AIC, and the model with an additive genetic factor (ACE) came in second. Due to the small statistical power, we hypothesise that the model with both genetic and environmental effects (ACE) was the better model. Choosing the ACE-model we found a heritability of clubfoot of 30 %. Regression coefficient for age was -0.002 (-0.011 to 0.005), indicating that there has been no change in prevalence of clubfoot over the 50-year age span we examined.

DISCUSSION

We conclude that non-genetic factors must play a role, and a genetic factor might contribute, in the aetiology of congenital clubfoot.

The Danish Twin Registry in the New Millennium

The Danish Twin Registry is the oldest national twin register in the world, initiated in 1954, and, by the end of 2005, contained more than 75,000 twin pairs born in the between 1870 and 2004. The Danish Twin Registry is used as a source for studies on the genetic influence on normal variation in clinical parameters associated with the metabolic syndrome and cardiovascular diseases, clinical studies of specific diseases, and aging and age-related health problems. The combination of survey data, clinical data and linkage to national health-related registers enables follow-up studies of both the general twin population and twins from clinical studies. This paper summarizes the newest extension of the register and gives examples of new developments and phenotypes studied.

Bilateral clubfoot in three homozygous preterm triplets

The etiology of congenital idiopathic talipes equinovarus deformity is unclear. Studies on populations, families, and twins have suggested a genetic component. However, the mode of inheritance does not fit classic patterns. The intrauterine posture and environmental and developmental causative factors have also been associated with the deformity. Neurologic, muscular, bony, connective tissue, and vascular structures can be affected. We present the case of monochorionic triplets with bilateral congenital idiopathic talipes equinovarus deformities. To the best of our knowledge, such a presentation has not been previously described and supports a genetic etiology of congenital idiopathic talipes equinovarus deformity.

Variants in genes that encode muscle contractile proteins influence risk for isolated clubfoot

Isolated clubfoot is a relatively common birth defect that affects approximately 4,000 newborns in the US each year. Calf muscles in the affected leg(s) are underdeveloped and remain small even after corrective treatment. This observation suggests that variants in genes that influence muscle development are priority candidate risk factors for clubfoot. This contention is further supported by the discovery that mutations in genes that encode components of the muscle contractile complex (MYH3, TPM2, TNNT3, TNNI2, and MYH8) cause congenital contractures, including clubfoot, in distal arthrogryposis (DA) syndromes. Interrogation of 15 genes encoding proteins that control myofiber contractility in a cohort of both non-Hispanic White (NHW) and Hispanic families, identified positive associations (P < 0.05) with SNPs in 12 genes; only 1 was identified in a family-based validation dataset. Six SNPs in TNNC2 deviated from Hardy-Weinberg equilibrium in mothers in our NHW discovery dataset. Relative risk and likelihood ratio tests showed evidence for a maternal genotypic effect with TNNC2/rs383112 and an inherited/child genotypic effect with two SNPs, TNNC2/rs4629 and rs383112. Associations with multiple SNPs in TPM1 were identified in the NHW discovery (rs4075583, P = 0.01), family-based validation (rs1972041, P = 0.000074), and case-control validation (rs12148828, P = 0.04) datasets. Gene interactions were identified between multiple muscle contraction genes with many of the interactions involving at least one potential regulatory SNP. Collectively, our results suggest that variation in genes that encode contractile proteins of skeletal myofibers may play a role in the etiology of clubfoot.

Is there evidence for aetiologically distinct subgroups of idiopathic congenital talipes equinovarus? A case-only study and pedigree analysis

BACKGROUND

Idiopathic congenital talipes equinovarus (CTEV) is a common developmental foot disorder, the aetiology of which remains largely unknown. Some aspects of the epidemiology suggest the possibility of aetiologically distinct subgroups. Previous studies consider CTEV as a homogenous entity which may conceal risk factors in particular subgroups. We investigate evidence for aetiologically distinct subgroups of CTEV.

METHODS

Parents of 785 probands completed a postal questionnaire. Family pedigrees were compiled by telephone. Case-only analysis was used to investigate interactions between risk factors and sex of the proband, CTEV laterality and CTEV family history.

RESULTS

The male:female ratio was 2.3:1, 58% of probands were affected bilaterally and 11% had a first-second degree family history. There were modest interactions between family history and twin births (multivariate case - only odds ratio [ORca] = 3.87, 95%CI 1.19-12.62) and family history and maternal use of folic acid supplements in early pregnancy (ORca = 0.62, 95%CI 0.38-1.01); and between sex of the proband and maternal alcohol consumption during pregnancy (female, positive history and alcohol consumed: ORca = 0.33, 95%CI 0.12-0.89). Previous reports of an interaction between maternal smoking and family history were not confirmed. Relatives of female probands were affected more often than relatives of male probands.

CONCLUSIONS

These results provide tentative evidence for aetiologically distinct CTEV subgroups. They support the 'Carter effect', suggesting CTEV develops though a multifactorial threshold model with females requiring a higher risk factor 'load', and suggest areas where future aetiological investigation might focus. Large multi-centre studies are needed to further advance understanding of this common condition.

Perinatal outcome of prenatally diagnosed congenital talipes equinovarus

OBJECTIVE

The purpose of this study was to investigate the perinatal outcome of prenatally diagnosed congenital talipes equinovarus.

METHODS

This was a retrospective observational study of all cases of prenatally diagnosed congenital talipes equinovarus referred to a major tertiary fetal medicine unit. Cases were identified from the fetal medicine and obstetric databases and pregnancy details and delivery outcome data obtained. Details of termination of pregnancy, number of patients undergoing karyotyping as well as details of prenatal classification of severity were recorded.

RESULTS

A total of 174 cases were identified. Of these, outcome data was available for 88.5% (154/174) of the pregnancies. Eighty three (47.7%) of cases were isolated and 91 cases (52.3%) were associated with additional abnormalities. There was a significant difference in birth weights between the two cohorts. Bilateral abnormality tended to be more severe. A high caesarean section rate was noted overall and a high preterm delivery rate seen in the isolated group.

CONCLUSION

This study is important because it provides contemporary data that can be used to counsel women prenatally. In particular, the raised risk of preterm delivery and caesarean section as well as the increased severity of the condition when both feet are affected should be discussed. The poor perinatal outcome when additional anomalies are present and the increased risk of aneuploidy are also important factors.

Smoking, the xenobiotic pathway, and clubfoot

BACKGROUND

Isolated clubfoot is a common orthopedic birth defect that affects approximately 135,000 newborns worldwide. It is characterized by ankle equinus, hindfoot varus, and forefoot adductus. Although numerous studies suggest a multifactorial etiology, the specific genetic and environmental components have yet to be delineated. Maternal smoking during pregnancy is the only common environmental factor consistently shown to increase the risk for clubfoot. Moreover, a positive family history of clubfoot, in conjunction with maternal smoking, increases the risk 20-fold. These findings suggest that genetic variation in smoking metabolism (xenobiotic) genes may increase susceptibility to clubfoot. Based on this reasoning, we interrogated eight candidate genes from the xenobiotic metabolism.

METHODS

Twenty-two single-nucleotide polymorphisms and two null alleles in these genes (CYP1A1, CYP1A2, CYP1B1, CYP2A6, EPHX1, NAT2, GSTM1, and GSTT1) were genotyped in a dataset composed of non-Hispanic white and Hispanic multiplex and simplex families.

RESULTS

Only rs1048943/CYP1A1 had significantly altered transmission in the aggregate and multiplex non-Hispanic white datasets (p = 0.003 and p = 0.009, respectively). Perturbation of CYP1A1 can cause an increase in harmful, adduct-forming metabolic intermediates. A significant interaction between EPHX1 and NAT2 was also found (p = 0.007). Importantly, for CYP1A2, significant maternal (p = 0.03; relative risk [RR] = 1.24; 95% confidence interval [CI], 1.04-1.44) and fetal (p = 0.01; RR = 1.33; 95% CI, 1.13-1.54) genotypic effects were identified, suggesting that both maternal and fetal genotypes can negatively impact limb development. No association was found between maternal smoking status and variation in xenobiotic metabolism genes.

CONCLUSION

Together, these results suggest that xenobiotic metabolism genes are unlikely to play a major role in clubfoot; however, perturbation of this pathway may still play a contributory role.

The association between idiopathic clubfoot and increased internal hip rotation

Clinical observation suggests the coexistence of increased internal hip rotation in limbs with clubfoot, thereby providing an additional, and perhaps overlooked, site of deformity to account for an intoeing gait in these limbs. Furthermore, assuming a genetic basis exists for exaggerated femoral and/or acetabular anteversion, which are the possible cause(s) for increased internal hip rotation, this association could provide another key to the multifactorial etiology of clubfoot. We asked whether such an association exists and retrospectively reviewed 114 children (178 clubfeet). We then tested for an association between clubfoot and increased internal hip rotation. These rotational measurements were compared with published normative data on torsion in children. In cases of unilateral clubfoot, an additional analysis compared the rotational profiles of the affected and unaffected extremities. Increased internal hip rotation occurred more frequently in limbs with idiopathic clubfoot. In patients with unilateral clubfoot, the affected extremities manifested greater internal hip rotation than the unaffected extremities, whereas the latter showed no difference in internal hip rotation compared with normative values. Clinical evaluation of intoeing in children with a history of clubfoot should include a rotational profile to determine the level(s) of deformity and guide therapeutic intervention.

LEVEL OF EVIDENCE

Level III, prognostic study (case control study). See Guidelines for Authors for a complete description of levels of evidence.

Congenital talipes equinovarus: a review of current management

Talipes equinovarus is one of the more common congenital abnormalities affecting the lower limb and can be challenging to manage. This review provides a comprehensive update on idiopathic congenital talipes equinovarus with emphasis on the initial treatment. Current management is moving away from operative towards a more conservative treatment using the Ponseti regime. The long-term results of surgical correction and the recent results of conservative treatment will be discussed.