Disease-specific complications and multidisciplinary interventions in achondroplasia

Changes in the Alignment of the Spine and Lower Limb in Children With Achondroplasia Treated With Vosoritide: A Single-center, 1-year Follow-up Prospective Study

BACKGROUND

Achondroplasia (ACH) is the most common skeletal dysplasia and is characterized by a short-limbed short stature, sagittal spinal malalignment, and genu varum. Vosoritide promotes longitudinal bone growth in children with ACH; however, its effects on various disease-specific complications, other than short stature, are unknown. This study aimed to investigate the therapeutic effects of vosoritide on spinal and lower limb malalignment in children with ACH.

METHODS

This single-center, open-label, prospective study included patients with ACH aged younger than or equal to 15 years who received vosoritide treatment and had a minimum follow-up period of 1 year. To evaluate alignment after vosoritide treatment, radiologic parameters were measured from sagittal radiographs of the spine and anteroposterior radiographs of the bilateral lower limbs before the administration of vosoritide and 12 months after treatment. Paired t tests were used to compare parameters before and after vosoritide treatment.

RESULTS

Seventeen patients (mean age, 7.6±2.7 y) were included. After 1-year treatment of vosoritide, the mean height increased by 5.4±1.3 cm. Changes in spinal alignment after 1 year of vosoritide treatment were 1.5 degrees for cervical lordosis, -1.3 degrees for thoracic kyphosis, -2.8 degrees for thoracolumbar kyphosis, -5.2 degrees for lumbar lordosis (LL), -2.2 degrees for pelvic tilt, -2.6 degrees for pelvic incidence, -0.4 degrees for sacral slope, and 2.6 mm for C7 sagittal vertical axis. Alignment changes in the lower limbs were -3.4 degrees for mechanical axis angle (MAA), 1.7 degrees for mechanical lateral proximal femoral angle (mLPFA), -2.8 degrees for mechanical lateral distal femoral angle (mLDFA), -0.2 degrees for medial proximal tibial angle, and -0.5 degrees for lateral distal tibial angle. The LL, MAA, mLPFA, and mLDFA levels showed statistically significant changes towards the normal range after treatment.

CONCLUSIONS

One-year treatment of vosoritide decreased the exaggerated LL and improved genu varum deformity in children with ACH. Vosoritide therapy may not only increase longitudinal bone growth but also improve spinal and lower limb malalignment in children with ACH.

LEVEL OF EVIDENCE

Level II: prospective comparative study.

Meclozine and growth hormone ameliorate bone length and quality in experimental models of achondroplasia

INTRODUCTION

Achondroplasia (ACH) is a common skeletal dysplasia associated with short-limbed short stature caused by gain-of-function mutations in the fibroblast growth factor receptor 3 (FGFR3) gene. Meclozine was found to inhibit FGFR3 signaling using a drug repositioning strategy. In some countries, growth hormone (GH) has been employed to ameliorate short stature in children with ACH. This study aims to investigate the effects of meclozine and GH on bone growth and quality using an experimental model of ACH.

MATERIALS AND METHODS

Meclozine (2 mg/kg/day) and/or GH (0.35 mg/kg/day) were administered to a mouse model of ACH from the age of 7 to 56 days. Body length and body weight of each mouse were measured during these treatments. At the end of treatments, these mice were subjected to micro-computed tomography scans to measure the lengths of long bones and bone mineral density (BMD). The width of the growth plate was quantified by histological analysis.

RESULTS

The body and bone length of transgenic mice significantly increased after treatment with meclozine and GH, although there was no additive effect of the combination therapy on promoting bone growth. In contrast, BMD was additively increased by the combination therapy. The width of the growth plate in transgenic mice was significantly increased by both treatments, although the hypertrophic zone was enlarged by meclozine but not by GH.

CONCLUSION

Meclozine or GH may be an option for treating children with ACH to ameliorate bone length and quality, but the additive effect would be limited.

Feasibility study of the psychosocial effects of an online mindfulness intervention in children and adolescents with achondroplasia and their parents

INTRODUCTION

Achondroplasia is a common skeletal dysplasia caused by a mutation in the FGFR3 gene, leading to disproportionate short stature and various clinical features. Despite the absence of definitive pharmacological treatments, mindfulness-based interventions may offer psychosocial benefits for affected individuals and their families.

OBJECTIVES

This study aimed to assess the feasibility and psychosocial effects of an online mindfulness intervention for children and adolescents with achondroplasia and their parents.

METHODOLOGY

The intervention was an eight-week, synchronous online program with 15 participants: seven children and adolescents with achondroplasia and eight parents. Quantitative outcomes were assessed pre-and post-intervention using the State-Trait Anxiety Inventory for Children (STAIC) and the Multifactorial Self-Assessment Child Adaptation Test (TAMAI) for the younger participants, along with the Brief Symptom Inventory (BSI-18) for parents. Participant satisfaction was assessed using a customized survey, and qualitative data were collected through semi-structured interviews.

RESULTS

The study demonstrated high feasibility, with 84.61% adherence and 93.75% participant satisfaction. Average anxiety levels decreased in children and adolescents (30.60 ± 5.12 to 26.80 ± 6.94, p = .285) and parents (3.67 ± 3.98 to 1.00 ± .89, p = .066). Emotional regulation was the most reported improvement category by children and adolescents (31.4%), while general well-being was the most noted by parents (29.63%).

CONCLUSIONS

The results support the feasibility of this online mindfulness intervention for individuals with achondroplasia and their parents, indicating benefits for psychosocial well-being. Future studies should address these limitations by expanding sample sizes, exploring hybrid intervention models, and ensuring data anonymity. Integrating mindfulness into comprehensive psychosocial care strategies could enhance the quality of life for these populations.

Identification biomarkers in disease progression of obstructive sleep apnea from children serum based on WGCNA and Mfuzz

Obstructive sleep apnea (OSA) syndrome is a prevalent form of respiratory sleep disorder, with an increasing prevalence among children. The consequences of OSA include obesity, diabetes, cardiovascular disease, and neuropsychological diseases. Despite its pervasive impact, a significant proportion of individuals especially children remain unaware that they suffer from OSA. Consequently, there is an urgent need for an accessible diagnostic approach. In this study, we conducted a bioinformatic analysis to identify potential biomarkers from a proteomics dataset comprising serum samples from children with OSA in the progression stage. In the Gene Set Enrichment Analysis (GSEA), we observed that the complement and immune response pathways persisted throughout the development of OSA and could be detected in the early stages. Subsequent to soft clustering and WGCNA analysis, it was revealed that the Hippo pathway, including ITGAL and FERMT3, plays a role in mild OSA. The analysis revealed a significant alteration of the complement and coagulation pathways, including TFPI and MLB2, in moderate OSA. In severe OSA, there was an association between hypoxia and the extracellular matrix (ECM) receptor interaction and collagen binding. In summary, it can be posited that the systemic inflammation may persist throughout the progression of OSA. Furthermore, severe OSA is characterized by abnormal vascular endothelial function, which may be attributed to chronic hypoxia. Finally, four potential biomarkers (ITGAL, TFPI, TTR, ANTXR1) were identified based on LASSO regression, and a prediction model for OSA progression was constructed based on the biomarkers.

Achondroplasia current concept of orthopaedic management

Achondroplasia, the most common form of inherited disproportionate short stature, is caused by mutations in the fibroblast growth factor receptor 3 gene. The typical clinical features of achondroplasia include short stature, rhizomelic disproportion, joint hyperlaxity, spinal deformity and deformity of the upper and lower limbs. The latter are among the challenges of state-of-the-art orthopaedic treatment plans and significantly contribute to the burden of the disease in individuals with achondroplasia. Multidisciplinary preoperative individual decision-making concerning surgical interventions should be considered. New medical treatments for achondroplasia have been developed and (some) have been approved for clinical use in several countries. While the number of research articles on achondroplasia is increasing rapidly, many unknown or controversial orthopaedic topics remain. Furthermore, in view of new medical developments with improvements in growth and potentially other effects, the timing and algorithms of orthopaedic treatments (e.g. guided growth, limb lengthening and deformity correction) need to be re-evaluated. While standing height is the primary research focus in medical therapy, it is crucial to comprehensively assess orthopaedic parameters in this multifactorial disease. The current treatment of patients with achondroplasia requires specialised multidisciplinary centres with transitional care and individual orthopaedic counselling.

Surgery for Spinal Stenosis in Achondroplasia: Causes of Reoperation and Reduction of Risks

BACKGROUND

Individuals with achondroplasia are prone to symptomatic spinal stenosis requiring surgery. Revision rates are thought to be high; however, the precise causes and rates of reoperation are unknown. The primary aim of this study is to investigate the causes of reoperation after initial surgical intervention in individuals with achondroplasia and spinal stenosis. In addition, we report on surgical techniques aimed at reducing the risks of these reoperations.

METHODS

A retrospective review was conducted over an 8-year period of all patients with achondroplasia at a single institution that serves as a large referral center for patients with skeletal dysplasias. Patients with achondroplasia who underwent spinal surgery for stenosis were identified and the need for revision surgery was studied. Data collected included demographic, surgical, and revision details. Fisher exact test was used to determine if an association existed between construct type and the need for revisions.

RESULTS

Thirty-three of the 130 (22%) patients with achondroplasia required spinal stenosis surgery. Twenty-four individuals who met the criteria were selected for analysis. The initial spine surgery was at an average age of 18.7 years (SD: 10.1 y). Nine patients (38%) required revision surgeries, and 3 required multiple revisions. Five of 9 (56%) of the revisions had primary surgery at an outside institution. Revision surgeries were due to caudal pseudarthrosis (the distal instrumented segment) (8), proximal junctional kyphosis (PJK) (7), and new neurological symptoms (7). There was a significant association found between construct type and the need for revision ( P =0.0111). The pairwise comparison found that short fusions were significantly associated with the need for revision compared with the interbody group ( P =0.0180). PJK was associated with short fusions when compared with the long fusion group ( P =0.0294) and the interbody group ( P =0.0300). Caudal pseudarthrosis was associated with short fusions when compared with the interbody group ( P =0.0015). Multivariate logistic regression found long fusion with an interbody was predictive of and protective against the need for revision surgery ( P =0.0246). To date, none of the initial cases that had long fusions with caudal interbody required a revision for distal pseudarthrosis.

CONCLUSIONS

In patients with achondroplasia, the rate of surgery for spinal stenosis is 22% and the risk of revision is 38% and is primarily due to pseudarthrosis, PJK, and recurrent neurological symptoms. Surgeons should consider discussing spinal surgery as part of the patient's life plan and should consider wide decompression of the stenotic levels and long fusion with the use of an interbody cage at the caudal level in all patients to reduce risks of revision.

LEVEL OF EVIDENCE

Level IV-Retrospective case series.

Demystifying Skeletal Dysplasias: A Practical Approach for the Pediatric Endocrinologist

BACKGROUND

Skeletal dysplasias encompass a group of genetic conditions associated with cartilaginous and bone tissue abnormalities, exhibiting a variable phenotype depending on the involved genes and mechanisms. Differential diagnosis is challenging as there are many skeletal dysplasias with similar phenotypes.

SUMMARY

In this review, we describe the physiology of skeletal development and the classification of skeletal dysplasias, followed by a practical approach to the workup of a child with suspected skeletal dysplasia. Diagnosis requires clinical, laboratory, and radiological evaluation to differentiate potential conditions in the patient. Genotyping has emerged as a confirmatory tool in many cases, enabling personalized treatment through a multidisciplinary approach and assessment of associated comorbidities.

KEY MESSAGES

As skeletal dysplasias often present with short stature, proportionate or disproportionate, the pediatric endocrinologist plays a crucial role in initial investigative and diagnostic guidance. Identifying the critical clinical manifestations, conducting appropriate initial screening tests, and referring for multidisciplinary follow-up contribute to expeditious diagnosis and family support.

Midline-Sparing Interapophysealaminar Decompression Technique for Management of Lumbar Stenosis in Pediatric Achondroplasia

INTRODUCTION

Achondroplasia is the most common form of short-limb dwarfism in humans, with an incidence of 1 in 25,000-40,000 live births. About one-third of achondroplasia patients will require operative intervention for lumbar spinal stenosis, generally presenting with progressive neurogenic claudication. The anatomy of the achondroplastic lumbar spine, with shortened pedicles, hypertrophic zygapophyseal joints, and thickened laminae frequently results in the development of multilevel interapophyseolaminar stenosis, while stenosis is usually absent at the mid-laminar levels secondary to pseudo-scalloping of the vertebral bodies. Treatment remains controversial, as disrupting the posterior tension band with complete laminectomies in the pediatric population puts patients at risk of developing post-laminectomy kyphosis.

CASE PRESENTATION

A 15-year-old girl with achondroplasia presented to clinic with debilitating neurogenic claudication in the setting of multilevel lumbar interapophyseolaminar stenosis. We present a technical case report of her successful surgical treatment using a midline posterior tension band sparing modification to the interapophyseolaminar decompression technique proposed by Thomeer et al. [J Neurosurg. 2002;96(3 Suppl l):292-7].

CONCLUSION

We demonstrate that an adequate interapophyseolaminar decompression can be achieved through the performance of bilateral laminotomies, bilateral medial facetectomies, and undercutting of the ventral spinous process while preserving supraspinous and interspinous ligament attachments. Given the generally multilevel nature of lumbar stenosis and longer life expectancies of pediatric achondroplasia patients, decompressive surgical interventions must aspire to minimize disruption of spine biomechanics if fusion surgery is to be avoided.