Delayed diagnosis of mild mucopolysaccharidosis type IVA.

BACKGROUND: Mucopolysaccharidosis IVA (MPS IVA) is a lysosomal storage disease caused by biallelic variants in the N-acetylgalactosamine-6-sulfatase (GALNS) gene and is characterized by progressive and multi-system involvements, dominantly with skeletal deformities. A mild form of MPS IVA often presents with atypical symptoms and can go unrecognized for years. METHODS: The diagnosis of MPS IVA was confirmed via GALNS enzyme activity testing in leukocytes. Clinical features were collected. Molecular analysis was performed by next generation sequence and Sanger sequencing of the GALNS gene. The pathogenicity of the deep intron variant was verified by mRNA analyses. RESULTS: Thirteen patients with mild MPS IVA from six families were included. All probands first visit pediatric orthopedists and it took 5.6 years to be diagnosed after the disease onset. The most common symptoms in our series were waddling gait (85%), short neck (69%) and flat feet (62%). Radiologic findings indicated skeletal abnormalities in all patients, especially modification of the vertebral bodies (100%) and acetabular and femoral head dysplasia (100%). Five novel GALNS variants, including c.121-2_121-1insTTTGCTGGCATATGCA, E2 deletion, c.569 A > G, c.898 + 2 T > A, and c.1139 + 2 T > C, were identified. The most common variant, a deep intron variant NM_000512.5: c.121-210 C > T (NM_001323544.2: c.129 C > T, p.G43G), was revealed to result in an 11 bp deletion (c.128_138delGCGATGCTGAG, p.Gly43Aspfs*5) on GALNS mRNA in the GALNS transcript of NM_001323544.2. CONCLUSIONS: This study provides significant insights into the clinical features and molecular characteristics that contribute to the early diagnosis of mild MPS IVA. On the basis of our cohort, orthopedists need to be able to recognize signs and symptoms of mild MPS IVA as well as the molecular and biochemical diagnosis so that an early diagnosis and treatment can be instituted.

Single-cell RNA Seq reveals cellular landscape-specific characteristics and potential etiologies for adolescent idiopathic scoliosis.

BACKGROUNDS: Abnormal vertebral growth and development have been found in adolescent idiopathic scoliosis (AIS) patients, and the proliferation and differentiation of bone development-related cells play important roles in its pathogenesis. However, a comprehensive single-cell-level differentiation roadmap in AIS has not been achieved. METHODS: The present study compared the single-cell level cellular landscapes of spinal cancellous bone tissues between AIS patients and healthy subjects using high throughput single-cell RNA sequencing (scRNA-seq), which covers multiple cellular lineages including osteoblast, chondrocyte, osteoclast and related immunocytes. We constructed the differentiation trajectories of bone development-related cell lineages through pseudotime analysis, and the intercellular-communication networks between bone development-related cells and immunocytes were further developed. RESULTS: A total of 11 distinct cell clusters were identified according to the genome-wide transcriptome profiles. t-Distributed stochastic neighbor embedding (t-SNE) analysis showed that mesenchymal stem cells (MSC) were classified into three subtypes: MSC-LOXL2, MSC-IGFBP5, and MSC-GJA1. Gene ontology (GO) analysis showed that MSC-GJA1 might possess greater osteoblast differentiation potential than the others. MSC-IGFBP5 was the specific MSC subtype observed only in AIS. There were two distinct gene expression clusters: OB-DPT and OB-OLFML2B, and the counts of osteoblasts derived from AIS was significantly less than that of non-AIS subjects. In AIS patients, MSC-IGFBP5 failed to differentiate into osteoblasts and exhibited negative regulation of cell proliferation and enhanced cell death. CPC-PCNA was found to be the specific chondrocyte progenitor cell (CPC) subtype observed only in AIS patients. The cell counts of OC-BIRC3 in AIS were less than those in controls. Pseudotime analysis suggested two possible distinct osteoclast differentiation patterns in AIS and control subjects. Monocytes in AIS mainly differentiated into OC-CRISP3. CONCLUSIONS: Our single-cell analysis first revealed differences existed in the cellular states between AIS patients and healthy subjects and found the differentiation disruption of specific MSC and CPC clusters in AIS. Cell communication analysis provided the possible pathogenesis of osteoblast and chondrocyte differentiation dysfunction in AIS.

Finite element and biomechanical analysis of risk factors for implant failure during tension band plating.

OBJECTIVE: Tension band plating has recently gained widespread acceptance as a method of correcting angular limb deformities in skeletally immature patients. We examined the role of biomechanics in procedural failure and devised a new method of reducing the rate of implant failure. METHODS: In the biomechanical model, afterload (static or cyclic) was applied to each specimen. The residual stress of the screw combined with different screw sizes and configurations were measured and compared by X-ray diffraction. With regard to static load and similar conditions, the stress distribution was analyzed according to a three-dimensional finite element model. RESULTS: The residual stress was close to zero in the static tension group, whereas it was very high in the cyclic load group. The residual stress of screws was significantly lower in the convergent group and parallel group than in the divergent group. The finite element model showed similar results. CONCLUSIONS: In both the finite element analysis and biomechanical tests, the maximum stress of the screw was concentrated at the position where the screws enter the cortex. Cyclic loading is the primary cause of implant failure.

Polydactyly Patient Carried a Mutation of PTCH1 Which Has Been Identified in Nevoid Basal Cell Nevus Syndrome.

Polydactyly frequently exhibits autosomal dominant inheritance, which is characterized by supernumerary fingers or toes. The growth of the limb was controlled by three signaling pathways in three-dimensional axis. Sonic Hedgehog signaling, which controls the anterior to posterior (radial to ulnar) orientation has been suspected to be a main cause for polydactyly. To determine the pathogenesis of the patients with polydactyly, we recruited a polydactyly family with two patients. Taking advantage of next-generation sequencing technology, we applied whole-exome sequencing and Sanger sequencing to the proband and her daughter. The analysis of the whole-exome sequencing showed a heterozygous missense mutation c.3617G>A (p.R1206H) in the PTCH1 gene. The results of Sanger sequencing also verified this mutation. Our research discovered a candidate gene of polydactyly-PTCH1. We are the first to point out the relationship between polydactyly and PTCH1 mutation in human. As the PTCH1 gene mutations have been identified in nevoid basal cell nevus syndrome (NBCCS), and polydactyly is one phenotype of NBCCS, it may provide a new clue to the study of the genotype-phenotype correlations between the PTCH1 gene mutations and NBCCS.

Clinical experience of debridement combined with resorbable bone graft substitute mixed with antibiotic in the treatment for infants with osteomyelitis.

BACKGROUND: Osteomyelitis (OM) is an uncommon disease that originates from many different mechanisms in children. Treatment often involves a combination of surgical debridement combined and antibiotic therapy. The purpose of this article is to evaluate the effect of debridement combined with a new resorbable bone graft substitute (RBGS) mixed with antibiotics in the treatment of infants with OM. METHODS: Twenty-two patients diagnosed with OM at our institution underwent debridement combined with implantation of RBGS mixed with vancomycin within 48 h after admission. Clinical and epidemiological factors, preoperative and postoperative radiographs, and laboratory parameters, including white blood cell (WBC), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and neutrophil percentage (NEU%), were documented. The function of the involved extremity was evaluated at the final follow-up. RESULTS: The mean age was 6.3 ± 4.8 months (range, 0.5 to 12 months). The mean duration of the symptoms was 14.5 ± 8.4 days (range, 2 to 30 days). The average length of hospitalization was 13.7 ± 6.2 days (range, 6 to 28 days). 13.64% (3/22) had positive results of purulent material obtained at the time of open biopsy and 18.18% (4/22) had positive blood cultures. The most common sites were located in the proximal femur (12), the distal femur (3), and the proximal humerus (3). Ten patients presented with concurrent pyogenic arthritis, while another 12 infants suffered from simple isolated hematogenous OM. The mean follow-up time was 3.0 ± 1.6 years (range, 1.0 to 6.0 years). Seven of 22 patients (31.82%) had complications such as limb length deformity (LLD), avascular necrosis (AVN), and pathologic subluxation of the hip. Fifteen out of 22 (68.18%) patients achieved good results. Additionally, patients who had concomitant pyogenic arthritis were more likely to develop complications than those with isolated OM (p = 0.02). CONCLUSIONS: Early debridement combined with implantation of RBGS mixed with vancomycin in the treatment of infants with OM achieved acceptable results in this series. Compared to those with simple isolated OM, patients with secondary pyogenic arthritis had a more virulent course.

MicroRNA-18a inhibits cell growth and induces apoptosis in osteosarcoma by targeting MED27.

Osteosarcoma (OS) is a common malignant primary bone tumor and patients with OS are known to have a poor response to chemotherapy. MicroRNAs (miRNAs or miRs) are small non-coding RNA molecules (approximately 22 nucleotides in length) and they have recently become a topic for research as regards their role in cancer therapeutics. Previous studies have reported miR­18a expression in patients with OS is significantly decreased compared with that in normal adjacent tissue. miR­18a belongs to the miR­17­92 cluster encoded by the host gene MIR17HG. However, the detailed role of miR­18a in OS remains to be determined. In this study, we demonstrated that miR­18a mimics inhibited MG63 and Saos­2 cell viability and migration. In addition, flow cytometry assay revealed that miR­18a induced OS cell apoptosis. Western blot analysis indicated that the expression levels of Bcl­2 and p­Akt were downregulated, while the levels of cleaved caspase­3 and Bax proteins were upregulated by miR­18a. Moreover, we demonstrated that mediator complex subunit 27 (MED27) was the target of miR­18a through dual luciferase assay. Finally, data from in vivo experiments indicated that tumor growth in mice was significantly suppressed by miR­18a mimics, accompanied by a decrease in the percentage of Ki67-positive cells, and by the downregulation in MED27 and p­Akt protein expression levels. The findings of the present study may aid in the clarification of the function of miR­18a, particularly as regards its role in the regulation of OS cell apoptosis, and indicate that MED27 may be a potential novel therapeutic target in the treatment of OS.

Is it worthwhile to screen the hip in infants born with clubfeet?

PURPOSE: There is some disagreement about whether idiopathic congenital talipes equinovarus (CTEV) increases the risk of neonatal developmental dysplasia of the hip (DDH). This study aimed to investigate the incidence of DDH in our infants with idiopathic CTEV. METHODS: We conducted an observational cohort study over a three-year period to assess the relationship between idiopathic CTEV and DDH. All neonates younger than six weeks with idiopathic CTEV who were treated in our medical centre were admitted to this study. Each subject underwent hip ultrasound examination using the Graf method at the age of six weeks. DDH was diagnosed when a hip was type IIa(-) or worse according to the Graf classification of sonographic hip type. RESULTS: A total of 184 patients were diagnosed with idiopathic CTEV and underwent hip sonography. In total, seven hips of five individuals underwent treatment (four girls and one boy). The results indicated that 2.7% of babies (five of 184) with idiopathic CTEV had DDH. However, we did not find any statistically significant difference (p = 0.5776) in the Pirani scores between the DDH group and group with normal hips. CONCLUSIONS: This study revealed that the idiopathic CTEV group had a greater incidence of DDH in comparison with the general population. It is recommended that hip sonography be undertaken particularly in patients with idiopathic CTEV.

Posterior interosseous nerve entrapment after Monteggia fracture-dislocation in children.

OBJECTIVE: Although most of nerve injuries associated with Monteggia fracture-dislocation in children are neurapraxias and will recover spontaneously after conservative treatment, surgical exploration of the involved nerve is always required in the cases with the entrapment of posterior interosseous nerve (PIN). However, the necessity and time frame for surgical intervention for specific patterns of nerve dysfunction remains controversial. The aim of the report is to observe and understand the pathology of PIN injury associated with Monteggia fracture-dislocation in children, and to propose the possible indication for the exploration of nerve. METHODS: Eight cases, six boys and two girls, with Monteggia fracture-dislocation complicated by PIN injury, managed operatively at the authors?Hospital from 2007 to 2008 were retrospectively reviewed. All the patients underwent the attempted closed reduction before they received exploration of PIN, with open reduction and internal fixation or successful closed reduction. RESULTS: The PIN was found to be trapped acutely posterior to the radiocapitellar joint in 4 out of 5 Type III Bado's Monteggia fractures. In the remaining cases, since there were longer time intervals from injury to operation, chronic compressive changes and epineural fibrosis of radial nerve were visualized. After a microsurgical neurolysis performed, the complete recovery in the nerve function was obtained in all the cases during the follow-up. CONCLUSION: The findings from this study suggest that every case of type III Monteggia fracture-dislocation with decreased or absent function of muscles innervated by PIN and an irreducible radial head in children should be viewed as an indication for immediate surgical exploration of the involved nerve to exclude a potential PIN entrapment.

[Treatment of old united lateral condyle fractures of humerus in children].

OBJECTIVE: To analyze the treatment of old united lateral condyle fractures of humerus in children. METHODS: From January 1997 to February 2002, 13 cases of old united lateral condyle fractures of humerus were treated. There were 11 boys and 2 girls. Their age was from 4 to 11 years (7.2 years on average). The primary diagnosis results were 4 cases of degree I fracture, 5 cases of degree II fracture and 4 indefinitely diagnosed cases. Elbow extension disorder occurred in 13 cases, which was limited 30-70. The elbow flexion was limited more than 90 degrees. X-ray films showed 10 nonunion and 3 malunion of fracture. The time from injury to operation was 32 to 81 days (56 days on average) in 12 cases and 6 months in 1 case. All cases were treated by open reduction and internal fixation. One case was treated combined with implanting bone. RESULTS: After a follow-up of 3 to 8 years (5.4 years on average), no cubitus varus or valgus occurred. Five cases had growth disturbances of the lateral condyle of the distal humerus. The movement of these elbow joints improved from 40 degrees to 70 degrees (56 degrees on average). The time of clinical bone union was 6 to 8 weeks and no nonunion and delayed union were observed in X-ray films. CONCLUSION: It is important to accurately diagnose for treatment of lateral condyle fractures of the humerus in children so as to reduce the occurrence of malunion of fracture. It can save the joint function and reduce the cosmetic deformity effectively to operate as early as possible.