Lower limb pain following allogeneic hematopoietic stem cell transplantation in Japanese children.

BACKGROUND: Patients who undergo allogeneic hematopoietic stem cell transplantation (allo-HSCT) can experience musculoskeletal pains in their lower limbs in the early and late post-transplantation period. This study investigated demographics and clinical characteristics of the lower limb pain (LLP) among Japanese survivors of pediatric allo-HSCT. METHODS: A total of 143 consecutive Japanese patients who had undergone allo-HSCT less than 18 years of age in a single institute between 2005 and 2015 were reviewed. Patients referred for in-house orthopedic evaluation of their sustained LLPs that impaired ambulation were defined as LLP group. Illness/transplantation-related parameters were compared between LLP group and non-LLP group. RESULTS: Ninety children with a mean age of 8.5 years at transplantation were enrolled. Their median follow-up period following transplantation was 6.3 years (range, 2.1-12.5). There were four patients in LLP group, whose etiologies were AVN of the femoral head and insufficiency fracture (ISF) of the tibia or the medial cuneiform bone. Cumulative dose of steroids that administered from six months before transplantation to six months after discharge from hospitalization for transplantation was significantly higher in LLP group than non-LLP group. Additionally, the two groups differed significantly in terms of hospitalization period after transplantation. LLP caused by AVN of the femoral head manifested between six months and two years, whereas that caused by ISF within the first six months after transplantation. CONCLUSIONS: The incidence of sustained LLP that impairs ambulation following contemporary allo-HSCT is not common in Japanese pediatric survivors. The risk of developing musculoskeletal LLP may increase with a higher steroid dosage in the peri-transplant period. LLP caused by AVN of the femoral head is likely to manifest later than that caused by ISF.

Asfotase alfa has a limited effect in improving the bowed limbs in perinatal benign hypophosphatasia: A case report.

Hypophosphatasia (HPP) is a rare skeletal dysplasia characterized by impaired bone mineralization, caused by loss-of-function mutations in the tissue-nonspecific alkaline phosphatase (TNSALP) gene. Enzyme replacement therapy (ERT) by administration of asfotase alfa was reported to improve the survival rate, bone mineralization, and short stature in the severe form of HPP. However, the effect of asfotase alfa in improving the skeletal phenotypes for the mild form of HPP has not been elucidated. We report a case with perinatal benign HPP who had compound heterozygous mutations of p.F327L and p.R30X in the TNSALP gene. No hypomineralization was seen in the radiographs from the neonatal period, but bowing of the femurs and ulnares bilaterally was persistent. ERT was administered during the age of 7.8 to 10.8 yr, although there was an interruption in the treatment for one year. The bowed femurs and ulnares were not improved by the treatment with asfotase alfa at the age of 10.8 yr. Bone mineral density of the lumbar spine was between -0.5 and -1.0 of the z-score, and the patient's height was about -2.0 SD during the treatment. Asfotase alfa might have a limited effect in improving the bowed limbs in perinatal benign hypophosphatasia.

A retrospective comparative study of corrective osteotomy for tibial deformities with the multiaxial correction fixator and the circular fixator.

PURPOSE: A multiaxial correction (MAC) fixator is a monolateral type of fixator that can correct multi-planer deformities. The purpose of this study is to compare the clinical outcome of correction for tibial deformities with the MAC fixator and the circular external fixators. METHODS: We retrospectively reviewed consecutive patients reconstructed with the MAC fixator (MAC group) or circular external fixators (Ring group) due to the congenital diseases or residual conditions after treatment of trauma, infection, tumor, or limb lengthening between 2003 and 2016. RESULTS: The 30 patients who had angular tibial deformity were included. In patients with tibia vara or lateral bowing, the average pre-operative mechanical medial proximal tibial angle (mMPTA) of the MAC group and the Ring group was significantly increased to 86.9 ± 3.5° in the MAC group and 88.0 ± 3.6° in the Ring group postoperatively. Medial bowing was also successfully corrected in both groups. Regarding the sagittal alignment, post-operative anatomical posterior proximal tibial angle (aPPTA) of the MAC group was deteriorated after coronal correction. The operative time was significantly shorter in the MAC group than the Ring group (p < 0.05). CONCLUSION: The MAC fixator successfully corrected coronal deformities of the tibia with shorter operative time, but it has a risk of occurrence of the procurvatum deformity compared with circular external fixators. Paying attention to the sagittal alignment, the MAC fixator can be one of the treatment options for correction of the coronal tibial deformities.

Legg-Calvé-Perthes disease in a patient with Bardet-Biedl syndrome: A case report of a novel MKKS/BBS6 mutation.

This article reports a girl with Bardet-Biedl syndrome (BBS) having a novel causative mutation who developed Legg-Calvé-Perthes disease (LCPD). There exists a possibility that the prognosis of LCPD had been adversely affected by the concomitant BBS.

Pharmacokinetics and safety after once and twice a day doses of meclizine hydrochloride administered to children with achondroplasia.

Achondroplasia (ACH) is the most common short-limbed skeletal dysplasia caused by activating mutations in the fibroblast growth factor receptor 3 (FGFR3) gene. We identified that meclizine hydrochloride inhibited FGFR3 signaling in various chondrocytic cells and promoted longitudinal bone growth in mouse model of ACH. Meclizine has safely been used for more than 50 years, but it lacks the safety data for repeated administration and pharmacokinetics (PK) when administered to children. We performed a phase Ia study to evaluate the PK and safety of meclizine administered orally to ACH children. Twelve ACH children aged from 5 to younger than 11 years were recruited, and the first 6 subjects received once a day of meclizine in the fasted condition, subsequent 6 subjects received twice a day of meclizine in the fed condition. Meclizine was well tolerated in ACH children with no serious adverse events. The mean Cmax, Tmax, AUC0-24h, t1/2 during 24 hours in the fasted condition were 130 ng/mL, 1.7 hours, 761 ng·h/mL, and 8.5 hours respectively. The simulation of repeated administration of meclizine for 14 days demonstrated that plasma concentration apparently reached steady state around 10 days after the first dose both at once a day and twice a day administration. The AUC0-10h of the fasting and fed condition were 504 ng·h/mL and 813 ng·h/mL, respectively, indicating exposure of meclizine increased with the diet. Although higher drug exposure was confirmed in ACH children compared to adults, a single administration of meclizine seemed to be well tolerated.

Severe achondroplasia due to two de novo variants in the transmembrane domain of FGFR3 on the same allele: A case report.

BACKGROUND: Achondroplasia (ACH), the most common form of short-limbed skeletal dysplasia, is caused by gain-of-function mutations in the fibroblast growth factor receptor 3 (FGFR3) gene. More than 97% of patients result from a heterozygous p.G380R mutation in the FGFR3 gene. We present here a child who had two de novo variants in the FGFR3 on the same allele, a common p.G380R mutation and a novel p.S378N variant. METHODS: A 3-year-old Japanese girl born from non-consanguineous healthy parents showed more severe clinical and radiological phenotypes than classic ACH, including severe short-limbed short stature with marked ossification defects in the metaphysis and epiphysis, hydrocephalus and cervicomedullary compression due to foramen magnum stenosis, prolonged pulmonary hypoplasia, and significant delay in the gross motor development. Genomic DNA was extracted from the proband and whole-exome sequencing was performed. The variants were subsequently confirmed by Sanger sequencing. RESULTS: Mutation analysis demonstrated that the proband had p.S378N (c.1133G>A) and p.G380R (c.1138G>A) variants in the FGFR3 gene. Both variants were not detected in her parents and therefore considered de novo. An allele-specific PCR was developed in order to determine whether these mutations were on the same allele (cis) or on different alleles (trans). The c.1138G>A mutation was found in the PCR product generated with the primer for the mutant 1133A, but it was not detected in the product with the wild-type 1133G, confirming that p.S378N and p.G380R variants were located on the same allele (cis). CONCLUSION: This is the second case who had two FGFR3 variants in the transmembrane domain on the same allele. The p.S378N variant may provide an additive effect on the activating receptor with the p.G380R mutation and alter the protein function, which could be responsible for the severe phenotype of the present case.

Extensive Bone Lengthening for a Patient with Linear Morphea.

Localized scleroderma, also known as morphea, is a rare condition characterized by progressive sclerosis of the skin and associated atrophy of the underlying tissues. The linear type of localized scleroderma is the most frequent form in childhood, usually affecting unilateral extremities. Fibrosclerosis of the fasciae and muscles can spread across joints and impair the range of motion of the joint. Dysplastic and/or atrophic bones of the affected lower extremity can lead to clinically significant leg length discrepancy (LLD). Limb reconstruction surgery has rarely been indicated for LLD in patients with linear morphea. We report on a case of extensive bone lengthening for appreciable LLD in a pediatric patient with linear morphea. A Japanese girl with linear morphea underwent staged simultaneous lengthening of the femur and tibia twice at seven and eleven years of age using a unilateral external fixator. A healing index exceeded 100 days/cm except for the first femoral lengthening that was complicated by regenerate fracture. At the final follow-up, LLD of 38 mm remained, but she could walk independently without a brace or a crutch. Due to soft tissue tightness and poor regenerative ability in the affected limb, cautions should be taken to prevent regenerate fracture and/or malalignment of the limb.

Drop of egg production in chickens by experimental infection with an avian metapneumovirus strain PLE8T1 derived from swollen head syndrome and the application to evaluate vaccine.

Decreases in egg production and increased incidence of abnormal eggs due to malformation of egg shells were observed in specific pathogen free (SPF) 173-day-old laying hens inoculated intravenously with an avian metapneumovirus (aMPV) strain PLE8T1. This strain was derived from an isolate from broiler birds exhibiting swollen head syndrome (SHS). Some SPF birds inoculated with the virus showed, slight diarrhea without any respiratory symptoms. Thus, the PLE8T1 strain was used as a challenge virus to evaluate efficacy of aMPV vaccines. SPF chickens which received a live attenuated aMPV vaccine (NEMOVAC; Merial) at 7 or 77 days old and an inactivated aMPV vaccine (OVO-4; Merial) at 105 days old were protected against poor egg production caused by the challenge with the PLE8T1 strain. Thus, aMPV, the PLE8T1 strain passaged 22 times after isolation, from birds exhibiting SHS, could induce a drop in egg production in laying hens accompanied by malformation of egg shells. It was suggested that this challenge system could be applied to evaluate the efficacy of aMPV vaccine.