Suture Cells in a Mechanical Stretching Niche: Critical Contributors to Trans-sutural Distraction Osteogenesis.

Trans-sutural distraction osteogenesis has been proposed as an alternative technique of craniofacial remodelling surgery for craniosynostosis correction. Many studies have defined the contribution of a series of biological events to distraction osteogenesis, such as changes in gene expression, changes in suture cell behaviour and changes in suture collagen fibre characteristics. However, few studies have elucidated the systematic molecular and cellular mechanisms of trans-sutural distraction osteogenesis, and no study has highlighted the contribution of cell-cell or cell-matrix interactions with respect to the whole expansion process to date. Therefore, it is difficult to translate largely primary mechanistic insights into clinical applications and optimize the clinical outcome of trans-sutural distraction osteogenesis. In this review, we carefully summarize in detail the literature related to the effects of mechanical stretching on osteoblasts, endothelial cells, fibroblasts, immune cells (macrophages and T cells), mesenchymal stem cells and collagen fibres in sutures during the distraction osteogenesis process. We also briefly review the contribution of cell-cell or cell-matrix interactions to bone regeneration at the osteogenic suture front from a comprehensive viewpoint.

Finite element analysis of the effect of residual lateral wall volume on postoperative stability in intertrochanteric fractures.

BACKGROUND: Lateral wall fractures represent crucial risk factors for postoperative internal fixation failure in intertrochanteric femoral fractures. However, no consensus exists on the type of lateral wall fracture requiring interventional management. This study aimed to investigate the effect of residual lateral wall volume on the postoperative stability of intertrochanteric femur fractures with associated lateral wall fractures, providing valuable reference for the clinical management of the lateral wall. METHODS: Eleven bone defect models of intertrochanteric femur fractures with varying residual lateral wall volumes were constructed using finite element analysis. These models were fixed with proximal femoral nail antirotation (PFNA). Simulations of von Mises stress and displacement distribution of the PFNA and femur during normal walking were conducted. Statistical analysis was performed to assess the correlation between volume and the maximum von Mises stresses and displacements of the PFNA and femur. RESULTS: In all 11 models, the maximum von Mises stress and displacement of the helical blade, intramedullary nail, and femur occurred at the same locations. As residual lateral wall volume increased, the maximum von Mises stress and displacement of the helical blade, intramedullary nail, and maximum femoral displacement gradually decreased. However, the overall trend of the maximum femoral von Mises stress gradually decreased. At 70% retention of the residual lateral wall volume, there was a more pronounced change in the value of the maximum stress change of the helical blade and the intramedullary nail. Statistical analysis, including the Shapiro-Wilk test and Pearson correlation analysis, demonstrated a significant negative correlation between volume and the maximum von Mises stress and displacement of the helical blade, intramedullary nail, and femur. Linear regression analysis further confirmed this significant negative correlation. CONCLUSION: Finite element analysis of the residual lateral wall revealed a significant correlation between volume and the postoperative stability of intertrochanteric femur fractures. A volume of 70% may serve as the threshold for stabilizing the residual lateral wall. Volume emerges as a novel index for evaluating the strength of the residual lateral walls.

Simvastatin inhibits the adipogenesis of bone marrow­derived mesenchymal stem cells through the downregulation of chemerin/CMKLR1 signaling.

Simvastatin is effective in the treatment of osteoporosis, partly through the inhibition of the adipogenesis of bone­marrow derived mesenchymal stem cells (BMSCs). The present study focused on the mechanisms responsible for the inhibitory effects of simvastatin on adipogenesis and examined the effects of simvastatin on the expression of peroxisome proliferator­activated receptor γ (PPARγ), chemerin, chemokine­like receptor 1 (CMKLR1), G protein­coupled receptor 1 (GPR1) and the adipocyte marker gene, adiponectin. BMSCs were isolated from 4­week­old female Sprague­Dawley (SD) rats, and adipogenesis was measured by the absorbance values at 490 nm of Oil Red O dye. The expression of each gene was evaluated by western blot analysis or reverse transcription­quantitative PCR (RT­qPCR). The expression of chemerin increased during adipogenesis, while CMKLR1 exhibited a trend towards a decreased expression. On days 7 and 14, the simvastatin­treated cells exhibited a downregulated expression of chemerin, whereas the upregulated expression of its receptor, CMKLR1 was observed. The results also revealed that CMKLR1 is required for adipogenesis and the simvastatin­mediated inhibitory effect on adipogenesis. Simvastatin regulated adipogenesis by negatively modulating chemerin­CMKLR1 signaling. Importantly, simvastatin stimulation inhibited the upregulation of PPARγ and PPARγ­mediated chemerin expression to prevent adipogenesis. Treatment with the PPARγ agonist, rosiglitazone, partially reversed the negative regulatory effects of simvastatin. On the whole, the findings of the present study demonstrate that simvastatin inhibits the adipogenesis of BMSCs through the downregulation of PPARγ and subsequently prevents the PPARγ­mediated induction of chemerin/CMKLR1 signaling.

Comparison between Minimally Invasive Plate Osteosynthesis and Conventional Open Plating for Midshaft Clavicle Fractures: A Systematic Review and Meta-Analysis.

OBJECTIVE: The aim of this study was to compare the functional outcome and complications in midshaft clavicle fractures receiving minimally invasive plate osteosynthesis and conventional open plating. METHODS: Relevant studies were searched in the databases of Medline, EMBASE, Cochrane Library, Ovid, and Web of Science from inception to March 1, 2019. Pooled data were analyzed with Cochrane Collaboration's Review Manager 5.3. RESULTS: A total of 7 studies were included, of which 2 were randomized controlled trials, 3 were retrospective cohort studies, and 2 were prospective cohort studies including 316 patients. No statistical differences in functional outcome (weighted mean difference [WMD] = 0.99, P = 0.12), operation time (WMD = -10.44, P = 0.07) and time to bone union (WMD = -0.23, P = 0.70) were observed between the two groups. However, minimally invasive plate osteosynthesis reduced rates of skin numbness (odds ratio (OR) = 0.25, 95% CI : 0.13 to 0.48; P < 0.0001) and complications (OR = 0.33, 95% CI : 0.16 to 0.71; P = 0.005) compared with conventional open plating. CONCLUSION: This systematic review and meta-analysis found no differences in terms of functional outcomes, operation time, and fracture healing time between minimally invasive plate osteosynthesis and conventional open plating. However, minimally invasive plate osteosynthesis had apparent advantages in rates of skin numbness and complications.