Achondroplasia: Etiology, Clinical Presentation, and Management

Quality of Life in Children With Achondroplasia Undergoing Paired Limb Lengthening With an External Fixator and Modified Distraction Control: Observational Nonrandomized Study

BACKGROUND

Transosseous distraction osteosynthesis is prioritized in orthopedic care for children with achondroplasia. However, difficulties encountered during treatment and rehabilitation directly impact patients' quality of life. Using rod external fixators within a semicircular frame for osteosynthesis is less traumatic compared to spoke circular devices. Their straightforward assembly and mounting on the limb segment can help significantly reduce treatment duration, thereby improving children's quality of life during treatment and rehabilitation.

OBJECTIVE

This study aimed to conduct a comparative analysis of the quality of life (measured by postoperative pain syndrome, physical activity, and emotional state) among children with achondroplasia undergoing paired limb lengthening using either an external fixator with modified distraction control or a circular multiaxial system developed by the authors.

METHODS

This was an observational, prospective, nonrandomized, and longitudinal study with historical control. The study group consisted of 14 patients ranging from 5 to 15 (mean 7.6, SD 2.3) years old with a genetically confirmed diagnosis of achondroplasia. All patients underwent paired limb lengthening with a rod external fixator and a modified distraction control developed by the authors. A total of 28 limb segments, among them 4 (14%) humeri, 8 (29%) femurs, and 16 (57%) tibias, were lengthened in 1 round. Unpublished data from the previous study served as the control group, comprising 9 patients (18 limb segments) of the same age group (mean age at surgery 8.6, SD 2.3 years), who underwent limb lengthening surgery using a circular multiaxial system-2 (11%) humeri, 6 (33%) femurs, and 10 (56%) tibias. The Wong-Baker Faces Rating Scale was used to measure pain symptoms, while the Russified Pediatric Quality of Life (PedsQL) v4.0 questionnaire assessed quality of life.

RESULTS

During the latent phase (7 to 10 days after surgery), a more pronounced decrease in the indicators of physical activity and emotional state on the PedsQL v4.0 questionnaire was noted in the control group (mean 52.4, SD 4.8 versus mean 52.8, SD 5.5 points according to children's responses and their parents' responses, respectively) compared to the experimental group (mean 59.5, SD 6.8 points and mean 61.33, SD 6.5 points according to the children's responses and their parents' responses, respectively). The differences between the groups were statistically significant (P<.05 for children's responses and P<.01 for parents' responses). Importantly, 6 months after surgery, these quality-of-life indicators, as reported by children in the experimental group, averaged 70.25 (SS 4.8) points. Similarly, their parents reported a mean of 70.54 (SD 4.2) points. In the control group, the corresponding values were 69.64 (SD 5.6) and 69.35 (SD 6.2), respectively. There was no statistically significant difference between the groups.

CONCLUSIONS

The external fixator with modified distraction control developed by the authors provides a higher standard of living compared with the circular multiaxial system during the latency phase.

Clinical-genetic analysis of selected genes involved in the development of the human skeleton in 128 Czech patients with suspected congenital skeletal abnormalities

BACKGROUND

Congenital skeletal abnormalities are a heterogeneous group of diseases most commonly associated with small or disproportionate growth, cranial and facial dysmorphisms, delayed bone maturation, etc. Nonetheless, no detailed genotype-phenotype correlation in patients with specific genetic variants is readily available. Ergo, this study focuses on the analysis of patient phenotypes with candidate variants in genes involved in bone growth as detected by molecular genetic analysis.

METHODS

In this study we used molecular genetic methods to analyse the ACAN, COL2A1, FGFR3, IGFALS, IGF1, IGF1R, GHR, NPR2, STAT5B and SHOX genes in 128 Czech children with suspected congenital skeletal abnormalities. Pathogenic variants and variants of unclear clinical significance were identified and we compared their frequency in this study cohort to the European non-Finnish population. Furthermore, a prediction tool was utilised to determine their possible impact on the final protein. All clinical patient data was obtained during pre-test genetic counselling.

RESULTS

Pathogenic variants were identified in the FGFR3, GHR, COL2A1 and SHOX genes in a total of six patients. Furthermore, we identified 23 variants with unclear clinical significance and high allelic frequency in this cohort of patients with skeletal abnormalities. Five of them have not yet been reported in the scientific literature.

CONCLUSION

Congenital skeletal abnormalities may lead to a number of musculoskeletal, neurological, cardiovascular problems. Knowledge of specific pathogenic variants may help us in therapeutic procedures.

Achondroplasia in Latin America: practical recommendations for the multidisciplinary care of pediatric patients

Background

Achondroplasia is the most common bone dysplasia associated with disproportionate short stature, and other comorbidities, such as foramen magnum stenosis, thoracolumbar kyphosis, lumbar hyperlordosis, genu varum and spinal compression. Additionally, patients affected with this condition have higher frequency of sleep disorders, ear infections, hearing loss and slowed development milestones. Considering these clinical features, we aimed to summarize the regional experts’ recommendations for the multidisciplinary management of patients with achondroplasia in Latin America, a vast geographic territory with multicultural characteristics and with socio-economical differences of developing countries.

Methods

Latin American experts (from Argentina, Brazil, Chile and Colombia) particiáted of an Advisory Board meeting (October 2019), and had a structured discussion how patients with achondroplasia are followed in their healthcare centers and punctuated gaps and opportunities for regional improvement in the management of achondroplasia.

Results

Practical recommendations have been established for genetic counselling, prenatal diagnosis and planning of delivery in patients with achondroplasia. An outline of strategies was added as follow-up guidelines to specialists according to patient developmental phases, amongst them neurologic, orthopedic, otorhinolaryngologic, nutritional and anthropometric aspects, and related to development milestones. Additionally, the role of physical therapy, physical activity, phonoaudiology and other care related to the quality of life of patients and their families were discussed. Preoperative recommendations to patients with achondroplasia were also included.

Conclusions

This study summarized the main expert recommendations for the health care professionals management of achondroplasia in Latin America, reinforcing that achondroplasia-associated comorbidities are not limited to orthopedic concerns.

Evaluating the results of long tubular bone distraction with an advanced rod monolateral external fixator for achondroplasia

The work aimed to evaluate the effectiveness of the developed distraction system based on the rod external monolateral fixation mechanisms by comparing it with the classical technique of long tubular bones distraction based on the circular multi-axial system. The study included patients with a genetically confirmed diagnosis of achondroplasia. The experimental group consisted of 14 patients who underwent surgical limb lengthening by the rod monolateral external fixator with a distraction system developed by the authors. The lengthening was performed on 28 segments of tubular bones. The majority of the experimental group patients achieved the lengthening value close to the planned one and the deformation correction. The fixation period was averagely 83.8 ± 3.7 days, the regenerate length was 8.5 ± 0.6 cm, and the mechanical strength of the distraction regenerate was 10.3° ± 2.18°. The rod external fixator with a control distraction system developed by the authors has small dimensions and low weight of the external supporting elements of high durability. It is reported to provide a good psychological tolerance of the treatment process and significantly outperforms the circular multi-axis system. Considering the aforementioned, the proposed apparatus can grant good orthopedic care to patients with achondroplasia.

Real-time ultrasound-guided epidural anesthesia for cesarean section in a parturient with achondroplasia

Achondroplasia is a type of disproportionate dwarfism with short limbs and a normal-sized torso. This condition results in a potential spinal abnormality and a difficult airway may increase the anesthetic risk, not only in neuraxial anesthesia, but also in general anesthesia. We report a 25-year-old primigravida with achondroplasia who underwent cesarean section under epidural anesthesia with the assistance of real-time ultrasound guidance. A total dose of 17 mL 2% lidocaine with 7.5 μg sufentanil was administered via epidural catheter intermittently. The level of anesthesia reached T4. No other anesthetic was administered during the operation and the procedure was uneventful. The mother and her newborn were routinely discharged without any adverse events. During the follow-up at 10 months postoperatively, the patient did not have any discomfort. We suggest that titrated epidural anesthesia at the time of real-time ultrasound-guidance is a safe and effective epidural anesthesia for patients with achondroplasia.

Exclusive Neurogenic Bladder and Fecal Incontinency in an Achondroplasic Child Successfully Treated with Lumbar Foraminal Decompression

INTRODUCTION

Achondroplasia is a genetic disorder characterized by defects in the development of endochondral bone resulting in skeletal abnormalities like stenosis of the foramen magnum and of the spine, shortened limb bones, and macrocephaly. Congenital spinal stenosis is frequent and due to premature fusion of the pedicles to the laminae.

CASE PRESENTATION

We report a case of neurogenic bladder and fecal incontinence due to lumbar stenosis successfully treated with L1-L5 partial laminectomy and foraminotomy in a 7-year-old achondroplasic child.

DISCUSSION/CONCLUSION

To our knowledge, this is the first case report of exclusive neurogenic bladder and fecal incontinence in an achondroplasic child. Neurogenic bladder and fecal incontinence without motor impairment may be early and exclusive clinical findings of lumbar stenosis in children with achondroplasia.

Genetics for paediatric radiologists

An understanding of genetics and genomics is increasingly important for all clinicians. Next-generation genomic sequencing technologies enable sequencing of the entire human genome in short timescales, and are increasingly being implemented in health care systems. Clinicians across all medical specialties will increasingly use results generated from genomic testing to inform their clinical practice and provide the best quality of care for patients. These innovations are already transforming the diagnostic pathways for rare genetic diseases, including skeletal dysplasias, with an inevitable impact on the traditional roles of diagnosticians. This article covers the fundamentals of human genetics, mechanisms of genetic variation and the technologies used to investigate the genetic basis of disease, with a specific focus on skeletal dysplasias and the potential impact of genomics on paediatric radiology.

Successful Mechanical Thrombectomy Using Solumbra Technique In a 35-year-old Man With Achondroplasia: a case report

Background

Achondroplasia is one of the most common types of dwarfism and is inherited as an autosomal dominant disease. The patients with achondroplasia suffer from various complications such as craniofacial, central nervous system, spinal, respiratory and cardiac anomalies.

Case Description

We report a case of a 35-year-old man with achondroplasia who visited the emergency room with right hemiplegia and aphasia within 6 hours after onset. An Initial CT angiography showed the total occlusion of a left internal cerebral artery due to the thrombus. We treated the patient with endovascular thrombectomy using “Solumbra technique” with balloon guiding catheter. The procedure was successful and result was completely recanalized with Thrombolysis in Cerebral Infarction (TICI) scale 3 and the weakness also improved from grade II to grade IV.

Conclusion

Acute ischemic stroke patients with achondroplasia could be treated with mechanical thrombectomy.

A novel missense COL10A1 mutation: c.2020G>A; p. Gly674Arg linked with the bowed legs stature in the Schmid metaphyseal chondrodysplasia-affected Chinese lineage

To evaluate the clinical-phenotypic characteristics of Schmid metaphyseal chondrodysplasia (SMCD) inflicted by a novel missense mutation of COL10A1 gene: c.2020G > A; p.Gly674Arg.

A female child aged about 3 yrs. and 8 months was subjected to Radiograph test to validate the symptoms of SMCD. The polymorphism analysis by the next-generation sequencing (NGS) was performed using the peripheral blood DNA samples of the patient and other family inmates, including, the younger male sibling. The effect of the mutation on the non-collagenous carboxyl-terminal (NC1) domain of collagen X was studied using the SWISS-MODEL online server for trimer modelling; PROSA and PROCHECK-Ramachandran plot for structural validation; Mean Square Plot (RMSF) for structural rigidity.

Radiograph examination of lower limbs confirmed the bowed legs in both the patient and her younger brother (study groups). The inheritance of the novel missense mutation of COL10A1: c.2020G > A; p.Gly674Arg (at chromosome-6q22.1) was confirmed in the study groups from the SMCD-affected mother. The extended interactions of the mutant-Arg674 with the Ser552 and Phe589 (β strand B) in the NC1 domain of α1(X) chain monomer is more likely to intervene its trimer formation by weakening the structural rigidity of the crucial strand H compared to its wild type. This plausibly deters the collagen X synthesis inflicting the bowed legs with the altered distal ulna bone morphology in the study groups.

The inheritance of COL10A1 mutation: c.2020G > A; p.Gly674Arg has inflicted the SMCD with the characteristic bowed legs in the study groups. Radiograph and NGS could be a valid diagnostic module to initiate the treatment of SMCD.

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A novel missense COL10A1 mutation (c.2020G>A; p.Gly674Arg) of NC1 domain of collagen X preceding Schmid Metaphyseal Chondrodysplasia.

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COL10A1 mutation (p.Gly674Arg) and the disturbed trimer structure of α1(X) chain monomer of collagen X.

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COL10A1 mutation (p.Gly674Arg) and the reduced rigidity of α1(X) chain monomer of collagen X.

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The mutated NC1 domain of collagen X structure and the bowed legs stature.

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Cupping and fraying of the distal ulna bone regulated by the weakened rigidity of the α1(X) chain monomer of collagen X.

Results through skeletal maturity of planned fibular nonunion for the treatment of genu varum in achondroplasia: An observational retrospective study

Current surgical options for treating genu varum in achondroplasia include tibial and fibular osteotomy and growth modulation using plates and screws. However, a single surgeon consistently treated genu varum using a planned fibular nonunion (PFN). The purpose of this study is to describe his surgical technique and report radiographic and clinical outcomes for the cohort studied.This is an observational retrospective review. The cohort studied included patients with achondroplasia who had PFN surgery for the treatment of genu varum at a young age (<13 years) and was followed through to skeletal maturity. The surgery included meticulous closure of the periosteum over the remaining fibula. The surgery was considered a success if the patient did not require subsequent surgery and had acceptable or improved clinical alignment. Radiographic measures used to determine change in genu varum included the anatomic tibio-femoral angle (aTFA), tibia varus, and tibia-fibula ratio. Clinically, changes in lower limb alignment were defined using a plumb line and 6 categories of alignment ranging from extreme varus to valgus. Statistics were used to validate the plumb line categorization to available radiographic measures. Other appropriate statistical methods were used with P < .05 considered significant.Of the 53 PFN cases (27 patients) included in the study, 34 (64%) did not require subsequent surgery and had acceptable or improved alignment. The average age at surgery and follow-up was 6.1 and 17.0 years, respectively. For the 37 limbs (19 patients) with available radiographs, pre- and post-surgery radiographic measures significantly improved including aTFA (3° varus to 2° valgus, P = .003), tibia varus (2° varus to 3° valgus, P = .004), and the tibia-fibula ratio (0.977 to 1.013, P < .001). Clinically, 32 cases (60%) demonstrated significant improvement by translating into an improved alignment and 9 (17%) remained the same (P < .01). Complications were minimal and insignificant. Failures were readily managed by tibia-fibular osteotomies in adolescence and at maturity.PFN for the treatment of genu varum in young achondroplasia patients significantly improved radiographic and clinical measures of lower limb alignment through skeletal maturity with relatively few complications.