Advances in research on and diagnosis and treatment of achondroplasia in China

Technical Considerations of Complex Primary Total Hip Arthroplasty in a Rare Case of Combined Achondroplasia and Hereditary Multiple Exostosis Syndromes

INTRODUCTION

Combined achondroplasia and hereditary multiple exostosis (HME) syndrome is a rare autosomal dominant inherited skeletal dysplasia. We report, for the 1sttime, a complex primary hip arthroplasty in a patient with combined achondroplasia and HME syndrome. We emphasize to the femoral and acetabular surgical concerns and difficulties of the surgical exposure and soft tissue balancing for this complex procedure.

CASE REPORT

An ambulatory 66-year-old female Caucasian with achondroplasia and HME presented with the left hip pain, progressive walk disability and limited range of hip motion due to severe hip osteoarthritis. Full cemented primary total hip arthroplasty (THA) with an impaction grafting technique was performed; posterior lip augmentation device was implanted to improve stability. At 5 years follow-up, the patient remains ambulatory and pain-free with improved range of hip motion. No signs of aseptic loosening are present.

CONCLUSIONS

Cemented THA could be an efficient option to reconstruct the complex hip anatomy in patients with skeletal dysplasia.

Molecular Confirmation of G1138A Mutation in FGFR gene in Achondroplasia

INTRODUCTION

Achondroplasia is the most common form of skeletal dysplasia of genetic origin in humans which is characterized by disproportionate rhizomelic dwarfism. Heterozygous mutation in the transmembrane domain of the FGFR3 gene (4p16.3) occurs as a de novo mutation in most of the cases.

METHODS

DNA was isolated from seven samples, out of which, five had clinical features of Achondroplasia while one was dwarf but did not show symptoms of the disorder and one as negative control. PCR was performed for the region incorporating the hotspot region viz. 1138th nucleotide. PCR amplicon of size 164 bp was obtained from all the samples, and was sequenced.

RESULTS

Sequence analysis showed the presence of mutation (G to A transition) in all of the five samples. The five samples that showed the clinical features of Achondroplasia had mutation in the region being analyzed while the single patient who had no clinical manifestations of the disorder despite being dwarf had no such mutation. Among the five patients studied, one patient had a family history of Achondroplasia as observed through pedigree analysis while the remaining four cases were sporadic in nature.

CONCLUSIONS

This study further supports that the G1138A mutation is the one of the most common point mutation among Achondroplasia cases. Genetic diagnosis can be useful to identify the disease prenatally and differentiate other life threatening dwarfism for the safety of both mother and fetus.

Skeletal Dysplasias: Growing Therapy for Growing Bones

Skeletal dysplasias represent a large and diverse group of rare conditions affecting collagen and bone. They can be clinically classified based on radiographic and physical features, and many can be further defined at a molecular level (Bonafe et al., 2015). Early diagnosis is critical to proper medical management including pharmacologic treatment when available. Patients with severe skeletal dysplasias often have small chests with respiratory insufficiency or airway obstruction and require immediate intubation after birth. Thereafter a variety of orthopedic, neurosurgical, pulmonary, otolaryngology interventions may be needed. In terms of definitive treatment for skeletal dysplasias, there are few pharmacotherapeutic options available for the majority of these conditions. We sought to describe therapies that are currently available or under investigation for skeletal dysplasias.