Risk Factors for Adverse Radiographic Outcomes After Elastic Stable Intramedullary Nailing of Unstable Diaphyseal Tibia Fractures in Children.

OBJECTIVES: Elastic stable intramedullary nails (ESIN) are commonly utilized to treat unstable pediatric tibia fractures but have been associated with complications. The purpose of this study was to identify risk factors for adverse radiographic outcomes after ESIN of pediatric tibia fractures. METHODS: A retrospective review of all patients who underwent diaphyseal tibia fracture stabilization with ESIN between 2010 and 2018 at 3 pediatric level 1 trauma centers was performed. Inclusion criteria were open growth plates, no intra-articular or physeal fracture involvement, and radiographic follow-up until union. Patient demographics, injury mechanism, fracture characteristics, and implant fill relative to the medullary canal were recorded. Radiographic outcome measures included achievement of and time to union, residual angular deformity, and additional procedures. RESULTS: One hundred seventy-two patients met inclusion criteria and were followed for a mean of 1.2 years. Nonunions were observed in 3% of the patient cohort. Another 10% required >6 months to heal, but did not require further surgical intervention. Angular deformities were common with 57% having a residual deformity ≥5 degrees and 14% having a residual deformity ≥10 degrees. Of the patients with a residual deformity between 5 and 10 degrees, 3% were symptomatic, where as 26% of the patients with a residual deformity ≥10 degrees were symptomatic. Greater angular deformities were associated with open fractures, compartment syndrome, and longer time to union. Patient age, weight, tibial comminution, and canal fill were not associated with nonunions or malunions. CONCLUSIONS: ESIN of pediatric tibia fractures results in reliable healing for a majority of patients, but poses risks for residual angular deformities and delayed healing. Open fractures and compartment syndrome were associated with adverse radiographic outcomes.

Loss of MeCP2 in the rat models regression, impaired sociability and transcriptional deficits of Rett syndrome.

Mouse models of the transcriptional modulator Methyl-CpG-Binding Protein 2 (MeCP2) have advanced our understanding of Rett syndrome (RTT). RTT is a 'prototypical' neurodevelopmental disorder with many clinical features overlapping with other intellectual and developmental disabilities (IDD). Therapeutic interventions for RTT may therefore have broader applications. However, the reliance on the laboratory mouse to identify viable therapies for the human condition may present challenges in translating findings from the bench to the clinic. In addition, the need to identify outcome measures in well-chosen animal models is critical for preclinical trials. Here, we report that a novel Mecp2 rat model displays high face validity for modelling psychomotor regression of a learned skill, a deficit that has not been shown in Mecp2 mice. Juvenile play, a behavioural feature that is uniquely present in rats and not mice, is also impaired in female Mecp2 rats. Finally, we demonstrate that evaluating the molecular consequences of the loss of MeCP2 in both mouse and rat may result in higher predictive validity with respect to transcriptional changes in the human RTT brain. These data underscore the similarities and differences caused by the loss of MeCP2 among divergent rodent species which may have important implications for the treatment of individuals with disease-causing MECP2 mutations. Taken together, these findings demonstrate that the Mecp2 rat model is a complementary tool with unique features for the study of RTT and highlight the potential benefit of cross-species analyses in identifying potential disease-relevant preclinical outcome measures.

Elective musculoskeletal surgery is associated with postoperative weight changes in pediatric and adolescent patients.

Purpose: Patients of elective orthopedic surgeries often reduce activity levels during postoperative recovery. It is unclear whether these extended periods of modified activities lead to weight changes. The purpose of this study was to evaluate changes in body mass index percentile in pediatric patients over 2.5 years following primary musculoskeletal surgeries. Methods: Institutional records for utilized current procedural terminology codes were used to identify patients aged 21 years or younger who underwent elective surgery at a single pediatric orthopedic institution between October 2016 and December 2018. Non-primary surgeries and patients without preoperative body mass index measurements were excluded. Demographic characteristics, height, weight, and body mass index within 30 months of surgery were collected. Body mass index relative to age was calculated. Analysis of body mass index changes at follow-up intervals of 3-7, 9-18, and 24-30 months after surgery was performed for the overall sample, within surgical categories, and within preoperative weight classifications. Results: A total of 1566 patients (53.1% female, average age 12.4 years) were included. Over one-third of patients were overweight or obese at presentation. The average change in body mass index percentile relative to baseline was increased at all follow-up intervals. Values reached significance at 9-18 months (p = .002) and 24-30 months (p = .001). While underweight and normal-weight patients had increased body mass index at all three timepoints, overweight or obese patients decreased. Conclusions: Patients undergoing elective orthopedic procedures may experience significant changes in body mass index percentile postoperatively. At extremes of weight, patients experience improvement toward the mean, but most patients may undergo body mass index increases beyond what would be expected during normal growth. Level of evidence: Retrospective level III.