Subtrochanteric fracture after core decompression for osteonecrosis of the femoral head: a case report and literature review.

BACKGROUND: Osteonecrosis of the femoral head (ONFH) is a common clinical disease. Improper treatment can lead to femoral head collapse and hip joint dysfunction. Core decompression is particularly important for early ONFH. However, subtrochanteric fractures after core decompression cause some clinical problems. CASE PRESENTATION: This article describes a 34-year-old male patient with early ONFH. After core decompression, he suffered a subtrochanteric fracture of the femur while bearing weight on the affected limb when going up stairs. He was subsequently treated with open reduction and intramedullary nail fixation. CONCLUSION: When core decompression is used to treat ONFH, the location or size of the drill hole, whether a tantalum rod or bone is inserted, and partial weight-bearing of the affected limb may directly affect whether a fracture occurs after surgery. It is hoped that this case report can provide a reference for clinical orthopedic surgeons in the treatment of early ONFH.

MiR-132 regulates osteogenic differentiation via downregulating Sirtuin1 in a peroxisome proliferator-activated receptor ß/δ-dependent manner.

MicroRNAs (miRNAs) play significant roles in multiple diseases by regulating the expression of their target genes. Type 2 diabetes mellitus (T2DM) is a chronic endocrine and metabolic disease with complex mechanisms. T2DM can result in diabetic osteoporosis (DO), which is characterized by bone loss, decreased bone mineral density and increased bone fractures. The promotion of osteogenic differentiation of osteoblasts is an effective way to treat osteoporosis. In the present study, high glucose (HG) and free fatty acids (FFA) were employed to mimic T2DM in MC3T3-E1 cells. To induce osteogenic differentiation, MC3T3-E1 cells were cultured in osteogenic medium. The results showed that osteogenic differentiation was significantly suppressed by HG and FFA. We found that miR-132 expression was significantly upregulated and much higher in HG-FFA-induced cells than other selected miRNAs, indicating that miR-132 might play an important role in DO. Furthermore, overexpression of miR-132 markedly inhibited the expression of key markers of osteogenic differentiation and alkaline phosphatase (ALP) activity. Reciprocally, inhibition of miR-132 restored osteogenic differentiation, even under treatment with HG-FFA. We also showed that Sirtuin 1 (Sirt1) was one of the target genes of miR-132, whose expression was controlled by miR-132. Ectopic expression of Sirt1 reversed the decrease in osteogenic differentiation caused by miR-132 and HG-FFA. These results demonstrated the direct role of miR-132 in suppressing osteogenic differentiation through downregulating Sirt1. Moreover, we demonstrated that peroxisome proliferator-activated receptor ß/δ (PPARß/δ) was a downstream molecule of Sirt1, and its knockout by PPARß/δ siRNA significantly abolished the promotive effects of Sirt1 on osteogenic differentiation, indicating that Sirt1 functioned in a PPARß/δ-dependent manner. Taken together, we provide crucial evidence that miR-132 plays a key role in regulating osteogenic differentiation through Sirt1 in a PPARß/δ-dependent manner, indicating that miR-132 and Sirt1-PPARß/δ may act as potential therapeutic targets for T2DM-induced osteoporosis.

Reactive oxygen species induce cell death via Akt signaling in rat osteoblast-like cell line ROS 17/2.8.

In bones, osteoblasts are responsible for bone formation. The cell death of osteoblasts may cause a series of bone diseases and lead to bone loss, such as osteoarthrosis, hyperparathyroidism, and Paget's disease. Reactive oxygen species (ROS) are reported as a main factor for osteoblast cell death and further several bone diseases. However, the detailed mechanism is still largely unknown. Here, we found that ROS could induce cell death of rat osteoblast-like cell line ROS 17/2.8 via Akt (protein kinase B). Also, the mammalian target of rapamycin signaling was involved in this process. Our findings could help to reveal the cellular mechanism of osteoblast cell death, which is served for the pursuit of clinical treatment targets of relative bone diseases.

Comparison of 2 kinds of pedicle screws in primary spinal instrumentation: biomechanical and interfacial evaluations in sheep vertebrae in vitro.

STUDY DESIGN: Expansive pedicle screw (EPS) and polymethylmethacrylate-augmented pedicle screw (PMMA-PS) were inserted in sheep vertebrae in vitro and were evaluated by performing biomechanical tests, radiographic examinations and histological observations. OBJECTIVE: The objective of the study was to compare the biomechanical and interfacial performances of EPS and PMMA-PS in sheep lumbar vertebrae in vitro. SUMMARY OF BACKGROUND DATA: It is a great challenge for orthopedic surgeons performing transpedicular fixation in the osteoporotic spine. It was reported that either the EPS or PMMA-PS could increase the screw stability. However, there are no studies comparing the 2 kinds of screws especially in primary spinal instrumentation. METHODS: A total of 60 sheep lumbar vertebrae were randomly divided into 3 groups. A pilot hole was made in advance in all samples using the same method. Thereafter, the conventional pedicle screw (CPS) was inserted directly into the pilot hole in the CPS group; the hole in PMMA-PS group was first filled with polymethylmethacrylate (PMMA; 1.0 mL) and then inserted with CPS; and the EPS was inserted directly into the vertebrae in EPS group. After a period of 24 hours, biomechanical tests were performed to evaluate screw stability, and x-ray examination, micro-computerized tomography analysis, and histologic observation were performed to evaluate the interface between screw and bone. RESULTS: Compared with the stability of CPS, those of EPS and PMMA-PS were significantly enhanced. However, no significant differences were detected between the stabilities of EPS and PMMA-PS. The PMMA surrounding the screw blocked direct contact between bone and screw and formed a "screw-PMMA-bone" interface in the PMMA-PS group. There was a "screw-bone" interface in both CPS and EPS groups. Nevertheless, the expanded anterior part of EPS formed a claw-like structure pressing the surrounding bone trabeculae, which made the local bone tissue more compacted and denser than that in the CPS group. CONCLUSIONS: EPS can enhance the screw stability as markedly as the traditional PMMA-PS in primary surgery, and EPS can form a better immediate interface between screw and bone compared with PMMA-PS. EPS also can effectively avoid thermal injury, leakage, and compression caused by PMMA. A great feasibility was proved in this study to perform comparisons between the 2 kinds of pedicle screws in osteoporotic sheep vertebrae in vivo in the further research. In conclusion, we propose that EPS has a great application potential in augmentation of screw stability in the clinic.

Incidence and Risk Factors of the Caudal Screw Loosening after Pelvic Fixation for Adult Spinal Deformity: A Systematic Review and Meta-analysis.

The purpose of this study was to assess the factors affecting caudal screw loosening after spinopelvic fixation for adult patients with spinal deformity. This meta-analysis calculated the weighted mean difference (WMD) and odds ratio (OR) using Review Manager ver. 5.3 (RevMan; Cochrane, London, UK). The loosening group was older than the control group (WMD, 2.17; 95% confidence interval [CI], 0.48-3.87; p=0.01). The S2 alar-iliac (S2AI) could prevent the caudal screw from loosening (OR, 0.43; 95% CI, 0.20-0.94; p=0.03). However, gender distribution (p=0.36), the number of fusion segments (p=0.24), rod breakage (p=0.97), T-score (p=0.10), and proximal junctional kyphosis (p=0.75) demonstrated no difference. Preoperatively, only pelvic incidence (PI) in the loosening group was higher (WMD, 5.08; 95% CI, 2.71-7.45; p<0.01), while thoracic kyphosis (p=0.09), lumbar lordosis (LL) (p=0.69), pelvic tilt (PT) (p=0.31), pelvic incidence minus lumbar lordosis (PI-LL) (p=0.35), sagittal vertical axis (SVA) (p=0.27), and T1 pelvic angle (TPA) demonstrated no difference (p=0.10). PI-LL (WMD, 6.05; 95% CI, 0.96-11.14; p=0.02), PT (WMD, 4.12; 95% CI, 0.99-7.26; p=0.01), TPA (WMD, 4.72; 95% CI, 2.35-7.09; p<0.01), and SVA (WMD, 13.35; 95% CI, 2.83-3.87; p=0.001) were higher in the screw loosening group immediately postoperatively. However, TK (p=0.24) and LL (p=0.44) demonstrated no difference. TPA (WMD, 8.38; 95% CI, 3.30-13.47; p<0.01), PT (WMD, 6.01; 95% CI, 1.47-10.55; p=0.01), and SVA (WMD, 23.13; 95% CI, 12.06-34.21; p<0.01) were higher in the screw loosening group at the final follow-up. However, PI-LL (p=0.17) demonstrated no significant difference. Elderly individuals were more susceptible to the caudal screw loosening, and the S2AI screw might better reduce the caudal screw loosening rate than the iliac screws. The lumbar lordosis and sagittal alignment should be reconstructed properly to prevent the caudal screw from loosening. Measures to block sagittal alignment deterioration could also prevent the caudal screw from loosening.

[Virtual preoperative planning and 3D-printed templates for pre-contoured plates in treatment of acetabular posterior wall fractures].

OBJECTIVE: To evaluate the feasibility and accuracy of virtual preoperative planning and 3D-printed templates for pre-contoured plates for the treatment of posterior wall fractures of the acetabulum. METHODS: A retrospective analysis of 29 patients with posterior acetabular wall fractures treated between August 2017 and March 2021 were divided into 2 groups based on whether to use preoperative virtual planning and 3D printed template. In 3D-printing group, there were 14 patients, including 10 males and 4 females； aged from 21 to 53 years old；CT-based virtual surgical planning was done using Mimics and 3-Matic software and 3D-printed templates for pre-contoured plates were adopted. In conventional group, there were 15 patients, including 10 males and 5 females；aged from 19 to 55 years old；conventional method of intra-operative contouring to adapt the plate to the fracture region was adopted. Blood loss, surgical time, radiographic quality of reduction, and hip function were compared between groups. RESULTS: The difference in operation time and intraoperative blood loss was significant（P<0.05）. Twenty-three patients were followed up from 12 to 30 months, and the fractures in both groups healed with a healing time of 3 to 6 months. At the last follow-up, the Merle d'Aubign-Postel score of the 3D printed group was lower than that of the conventional group（P<0.05）, with no significant differences in walking ability, hip mobility and total score（P>0.05）. In 3D printing group, 6 cases were excellent, 5 cases were good, 3 cases were fair；in conventional group, 5 cases were excellent, 5 cases were good, 4 cases were fair, 1 case was worse；no significant difference between two groups（P>0.05）. CONCLUSION: Virtual preoperative planning and 3D-printed templates for pre-contoured plates can reduce operative time and the blood loss of surgery, improve the quality of reduction. This method is efficient, accurate and reliable to treat acetabular posterior wall fractures.

Design of 3D printing osteotomy block for foot based on triply periodic minimal surface.

The ankle joint, which connects the lower limbs and the sole of the foot, is prone to sprain during walking and sports, which leads to ankle arthritis. Supratroleolar osteotomy is an ankle preserving operation for the treatment of ankle arthritis, in which the osteotomy is an important fixing and supporting part. In order to avoid stress shielding effect as much as possible, the osteotomy block is designed as a porous structure. In this study, the osteotomy block was designed based on three-period minimal surface, and the designed structure was manufactured by 3D printing. The mechanical properties of different structures were studied by mechanical test and finite element simulation. In mechanical tests, the Gyroid structure showed a progressive failure mechanism from bottom to bottom, while the Diamond structure showed a shear failure zone at 45° Angle, which was not conducive to energy absorption and was more prone to brittle fracture than the Gyroid structure. Therefore, the Gyroid structure is valuable for further research in the development of porous osteotomy.

Multiple-Rod Constructs in Adult Spinal Deformity Surgery: A Systematic Review and Meta-Analysis.

The purpose of this research was to compare the therapeutic efficacy of multiple-rod constructs vis-a-vis 2-rod constructs in the treatment of adult spinal deformity. A systematic review and meta-analysis were performed to determine whether the multiple-rod construct outperformed the 2-rod construct. We initially retrieved 357 papers, but only 12 were chosen for further meta-analysis. The rod breakage rates in the multiple-rod and the 2-rod groups were 10.66% and 29.87%, respectively. The multiple-rod construct inhibited rod breakage (odds ratio [OR], 0.28; 95% confidence interval [CI], 0.19-0.41; p<0.001), pseudarthrosis (OR, 0.30; 95% CI, 0.18-0.50; p<0.001) and rod fracture at the osteotomy site (OR, 0.34; 95% CI, 0.13-0.89; p=0.03). Furthermore, the multiple-rod construct reduces the risk of revision surgery (OR, 0.38; 95% CI, 0.20-0.73; p=0.04) as well as the revision risk of pseudarthrosis/rod fracture in the multiple- rod group (OR, 0.31; 95% CI, 0.18-0.52; p<0.001), but increases the risk of caudal screw loosening (OR, 4.99; 95% CI, 1.87-13.30; p=0.001). There was no statistically significant difference in proximal junctional kyphosis (PJK) parameters (p=0.85), cerebrospinal fluid leakage (p=0.09), wound infection (p =0.71), age at surgery (p=0.62), gender distribution (p=0.93), body mass index (p =0.86), smoking status (p=0.05), hospital stay (p=0.09), osteoporosis (p=0.95), CoCr rod material (p=0.15), bone morphogenetic protein-2 (p=0.58), L5/S1 interbody fusion (p=0.07), high-grade osteotomies (p=0.07), the number of fusion levels (p=0.11), operation time (p=0.30), and blood loss volume (p=0.34). Regarding radiographic parameters, only preoperative sagittal vertical axis was found to be higher (weight means difference [WMD], 25.60; 95% CI, 15.43-35.77; p<0.001) in the multiple-rod group. There was no difference in preoperative Oswestry Disability Index (ODI) (WMD, -3.32; 95% CI, -7.38 to 0.73; p=0.11), but the multiple-rod group had a lower ODI at follow-up (WMD, -7.71; 95% CI, -11.62 to -3.86; p<0.001). Multiple-rod constructs could prevent rod breakage and pseudarthrosis while also lowering the revision rate, resulting in a better clinical outcome than the 2-rod construct. Nonetheless, due consideration should be given to PJK and screw loosening in multiple-rod constructs, possibly due to the increased stiffness caused by the multiple-rod structure.

Il-1ß Promotes Superficial Zone Cells Senescence in Articular Cartilage by Inhibiting Autophagy.

OBJECTIVE: The superficial zone cells in articular cartilage (SFZCs) have been identified as stem/progenitor chondrocytes and promoted cell self-renewal in the osteoarthritis (OA). Several studies emphasized the involvement of senescence and autophagy in OA. Interleukin-1ß (IL-1ß) is one of the main inflammatory mediators of OA, and whether it induces senescence and autophagy in SFZCs remains unclear. The present study aimed to investigate autophagy flux, mitochondrial function, and intracellular reactive oxygen species (ROS) that resulted in senescence in SFZCs induced by IL-1ß. METHODS: Using western blotting, reverse transcription-quantitative PCR, immunofluorescence, intracellular ROS detection, mitochondrial staining, and determination of mitochondrial membrane potential, we tested senescence and autophagy markers in SFZCs induced by IL-1ß in vitro. The consequences of mitochondrial function and ROS were also studied with IL-1ß-induced senescence. RESULTS: IL-1ß treatment decreased SFZC proliferation, induced SFZC senescence, and reduced SFZCs' chondrogenic differentiation capacity. Moreover, IL-1ß impaired autophagy flux, and the autophagy activator, rapamycin, attenuated the senescence of SFZCs. IL-1ß-induced autophagy defect resulted in mitochondrial dysfunction and overproduction of ROS, and autophagy activation notably protected against mitochondrial dysfunction and reduced the levels of ROS. Moreover, antioxidant N-acetylcysteine reversed the senescence of IL-1ß in SFZCs. CONCLUSION: IL-1ß promotes autophagy impairment and subsequently results in dysfunctional mitochondria and overproduction of ROS, which finally causes SFZC senescence.

Roles of Cartilage-Resident Stem/Progenitor Cells in Cartilage Physiology, Development, Repair and Osteoarthritis.

Osteoarthritis (OA) is a degenerative disease that causes irreversible destruction of articular cartilage for which there is no effective treatment at present. Although articular cartilage lacks intrinsic reparative capacity, numerous studies have confirmed the existence of cartilage-resident stem/progenitor cells (CSPCs) in the superficial zone (SFZ) of articular cartilage. CSPCs are characterized by the expression of mesenchymal stromal cell (MSC)-related surface markers, multilineage differentiation ability, colony formation ability, and migration ability in response to injury. In contrast to MSCs and chondrocytes, CSPCs exhibit extensive proliferative and chondrogenic potential with no signs of hypertrophic differentiation, highlighting them as suitable cell sources for cartilage repair. In this review, we focus on the organizational distribution, markers, cytological features and roles of CSPCs in cartilage development, homeostasis and repair, and the application potential of CSPCs in cartilage repair and OA therapies.

[Effect of computer virtual technique combined with pelvic reduction frame in the treatment of type C pelvic fracture].

OBJECTIVE: To investigate the short-term clinical effect of the computer virtual technique combined with pelvic reduction frame in the treatment of complex pelvic fractures. METHODS: Thirty patients with Tile C pelvic fractures treated by percutaneous minimally invasive pelvic reduction frame from April 2018 to April 2020 were retrospectively analyzed, including 21 males and 9 females, aged from 19 to 57 (39.40±9.85) years old. The patient's pelvic CT DICOM data were imported into Mimics software to reconstruct the virtual fracture model. Virtual reduction and nail placement were carried out on the fracture model, and then simulated fluoroscopy was carried out to record the ideal fluoroscopy orientation and angle to guide the correct fluoroscopy during operation. The operation time, fluoroscopy times and intraoperative blood loss were recorded. The quality of fracture reduction was evaluated by Matta image score standard, and the postoperative function was evaluated by Majeed function score standard. RESULTS: All 30 patients achieved closed reduction and percutaneous screw fixation. According to Matta score, the excellent and good rate of fracture reduction was 93.3%(28/30). A total of 67 channel screws were inserted, and the excellent and good rate was 98.5%(66/67). The operation time was (173.54±79.31) min, fluoroscopy time was (90.81±41.11) times, intraoperative blood loss was (81.21±43.97) ml. All incisions healed at one stage without broken nails or re-displacement of fractures. All patients were followed up for 12 months. At the final follow-up, Majeed function score was 73 to 94(85.66±5.33) scores. CONCLUSION: Computer virtual technology combined with pelvic reduction frame could rapidly, accurately and safely reduce and fix unstable pelvic fractures. Computer virtualization could help surgeons to recognition and understanding pelvic fractures, pelvic reduction frame could improve the surgeon's ability to manage complex and unstable pelvic injuries.

[Effectiveness of multidirectionally three-dimensional steel wire ring sleeve fixation in treatment of inferior patellar pole avulsion fractures].

OBJECTIVE: To explore the method and effectiveness of multidirectionally three-dimensional steel wire ring sleeve fixation in the treatment of inferior patellar pole avulsion fractures. METHODS: Betweern January 2015 and January 2019, 22 patients with inferior patellar pole avulsion fractures were admitted and treated. There were 12 males and 10 females. The age ranged from 20 to 69 years, with an average age of 39.4 years. The causes of injury included 9 cases of traffic accident and 13 cases of falling. All of them were unilateral closed injury of knee joint, including 7 cases of skin contusion around patella. Preoperative range of motion of the affected knee was (20.82±7.16)° (range, 10°-35°). The time from injury to operation ranged from 3 to 12 days, with an average of 5.9 days. During the operation, the inferior patellar avulsion fracture was reduced with forceps; the patella was circumferentially ligated through the distal bone surface of the fracture with 0.8 mm diameter steel wire; then 3 longitudinal bone tunnels were made in the upper patella, respectively. The 0.8 mm diameter steel wire passed through the bone tunnel, and the longitudinal ring was attached to the ring to fix the upper and inferior patellar fracture. Tighten the transverse and longitudinal rings with No.2 tendon suture line, then longitudinally ringed and sutured to strengthen the patella. The knee range of motion, fracture healing time, and complications were recorded. The functional recovery of the knee joint was evaluated by Böstman score. RESULTS: All incisions healed by first intention, and no incision related complications occurred. All the 22 patients were followed up 13 months to 5 years with an average of 26.7 months. The fracture healing time was 9-12 weeks (mean, 10.9 weeks). At last follow-up, the knee range of motion was (129.77±2.35)° (range, 126°-135°), showing significant difference when compared with preoperative one ( t=-67.022, P=0.000). The Böstman score ranged from 31 to 36, with an average of 34.3. No reduction loss, fracture of steel wire, failure of internal fixation, and other complications occurred during follow-up. CONCLUSION: Multidirectionally three-dimensional steel wire ring sleeve fixation in the treatment of inferior patellar pole avulsion fractures has the advantages of reliable fixation, early functional recovery, and fewer complications, so the effectiveness is satisfactory.

Development of a valid Chinese version of the Cumberland Ankle Instability Tool in Chinese-speaking patients with chronic ankle instability disorders.

As an effective scale for the condition assessment of patients with chronic ankle instability (CAI), the Cumberland Ankle Instability Tool (CAIT) is the most widely used scale, and its original version is written in English. Therefore, the purpose of our study is to apply the CAIT to Chinese patients and evaluate its responsiveness, reliability, and validity in terms of Chinese patients with CAI. First, we adapted the CAIT into the Chinese edition (CAIT-C), through which cross-cultural adaptation and translation can be carried out in a five-step procedure. Next, recruited patients completed the three periods of the Foot and Ankle Ability Measure (FAAM), CAIT-C, and the Medical Outcomes Study Short-Form 36 (SF-36) scales. Afterward, to assess the responsiveness, reliability, and validity, we calculated the standardized response mean (SRM), effect size (ES), Spearman's correlation coefficient (rs), minimal detectable change (MDC), standard error of measurement (SEM), intraclass correlation coefficient (ICC), and Cronbach's alpha. Generally, in the use of CAI, 131, 119, and 86 patients favorably completed the three periods of the scales. The CAIT-C was proven to have good test-retest reliability (ICC = 0.930) and fine internal consistency (Cronbach's alpha = 0.845-0.878). The low-value of MDC (0.04-2.28) and SEM (1.73) show it is possible to detect clinical changes when we take advantage of CAIT-C. Good or moderate correlations (rs = 0.422-0.738) were gained from the physical subscales of the SF-36 and the subscales of the FAAM and the CAIT-C. Fair or poor correlations (rs = 0.003-0.360) were gained between the mental subscales of the SF-36 and the CAIT-C, which sufficiently indicated that the CAIT-C had good validity. Moreover, good responsiveness was observed in the CAIT-C (ES = 1.316, SRM = 1.418). The CAIT-C scale is an effective, valid, and reliable tool to evaluate Chinese CAI patients.

MicroRNA­33 regulates the NLRP3 inflammasome signaling pathway in macrophages.

The nucleotide binding domain and leucine-rich repeat pyrin 3 domain (NLRP3) inflammasome/interleukin (IL)-1ß axis serves an essential role in regulating the development of rheumatoid arthritis (RA). The dysregulation of cellular metabolism, such as mitochondrial dysfunction, results in the activation of the NLRP3 inflammasome. microRNA (miR)­33 has previously been identified to be a regulator of lipid metabolism and mitochondrial function. However, whether miR­33 regulates the NLRP3 inflammasome/IL­1ß axis remains unknown. In the present study, it was observed that an miR­33 mimic or anti­miR­33 markedly stimulated or inhibited, respectively, IL­1ß protein expression levels in mouse peritoneal macrophages. Mechanistically, miR­33 upregulated the expression of NLRP3 mRNA and protein as well as caspase­1 activity in primary macrophages. In addition, the results demonstrated that miR­33 impaired mitochondrial oxygen consumption rates, resulting in the accumulation of cellular reactive oxygen species, which stimulated NLRP3 expression, caspase­1 activity and IL­1ß secretion. The results of the present study demonstrated that miR­33 levels and NLRP3 inflammasome activity were increased in peripheral blood monocytes from patients with RA patients compared with healthy donors. In conclusion, the present study identified miR­33 to be a positive regulator of the NLRP3 inflammasome in macrophages. The miR­33/NLRP3 inflammasome pathway may therefore be involved in RA development.

Peroxisome Proliferator-Activated Receptor α Facilitates Osteogenic Differentiation in MC3T3-E1 Cells via the Sirtuin 1-Dependent Signaling Pathway.

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease characterized by lack of insulin and high glucose levels. T2DM can cause bone loss and fracture, thus leading to diabetic osteoporosis. Promoting osteogenic differentiation of osteoblasts may effectively treat diabetic osteoporosis. We previously reported that Sirtuin 1 (Sirt1), a NAD+-dependent deacetylase, promotes osteogenic differentiation through downregulation of peroxisome proliferator-activated receptor (PPAR) γ. We also found that miR-132 regulates osteogenic differentiation by downregulating Sirt1 in a PPARß/δ-dependent manner. The ligand-activated transcription factor, PPARα, is another isotype of the peroxisome proliferator-activated receptor family that helps maintain bone homeostasis and promot bone formation. Whether the regulatory role of PPARα in osteogenic differentiation is mediated via Sirt1 remains unclear. In the present study, we aimed to determine this role and the underlying mechanism by using high glucose (HG) and free fatty acids (FFA) to mimic T2DM in MC3T3-E1 cells. The results showed that HG-FFA significantly inhibited expression of PPARα, Sirt1 and osteogenic differentiation, but these effects were markedly reversed by PPARα overexpression. Moreover, siSirt1 attenuated the positive effects of PPARα on osteogenic differentiation, suggesting that PPARα promotes osteogenic differentiation in a Sirt1-dependent manner. Luciferase activity assay confirmed interactions between PPARα and Sirt1. These findings indicate that PPARα promotes osteogenic differentiation via the Sirt1-dependent signaling pathway.

Biomechanical Comparison of Pedicle Screw Augmented with Different Volumes of Polymethylmethacrylate in Osteoporotic and Severely Osteoporotic Synthetic Bone Blocks in Primary Implantation: An Experimental Study.

This study was designed to compare screw stabilities augmented with different volumes of PMMA and analyze relationship between screw stability and volume of PMMA and optimum volume of PMMA in different bone condition. Osteoporotic and severely osteoporotic synthetic bone blocks were divided into groups A0-A5 and B0-B5, respectively. Different volumes of PMMA were injected in groups A0 to A5 and B0 to B5. Axial pullout tests were performed and F max was measured. F max in groups A1-A5 were all significantly higher than group A0. Except between groups A1 and A2, A3 and A4, and A4 and A5, there were significant differences on F max between any other two groups. F max in groups B1-B5 were all significantly higher than group B0. Except between groups B1 and B2, B2 and B3, and B4 and B5, there were significant differences on F max between any other two groups. There was significantly positive correlation between F max and volume of PMMA in osteoporotic and severely osteoporotic blocks. PMMA can significantly enhance pedicle screw stability in osteoporosis and severe osteoporosis. There were positive correlations between screw stability and volume of PMMA. In this study, injection of 3 mL and 4 mL PMMA was preferred in osteoporotic and severely osteoporotic blocks, respectively.

[The design of an anti-rotation reduction internal fixator and its applications in spine fracture surgeries].

This article introduces a new-type anti-rotation reduction internal fixator, which can be applied in various spine fractures and dislocations in order to shorten the operation time, to raise reduction effect, and to reduce the complications such as the loss of reduction, broken nail, broken rod etc. Biomechanical tests and clinical applications have proved that the internal fixator has the features of a short operation time, a definite fixation and few complications.

Reciprocal inhibition between miR-26a and NF-κB regulates obesity-related chronic inflammation in chondrocytes.

Obesity is causally linked to osteoarthritis (OA), with the mechanism being not fully elucidated. miRNAs (miRs) are pivotal regulators of various diseases in multiple tissues, including inflammation in the chondrocytes. In the present study, we for the first time identified the expression of miR-26a in mouse chondrocytes. Decreased level of miR-26a was correlated to increased chronic inflammation in the chondrocytes and circulation in obese mouse model. Mechanistically, we demonstrated that miR-26a attenuated saturated free fatty acid-induced activation of NF-κB (p65) and production of proinflammatory cytokines in chondrocytes. Meanwhile, NF-κB (p65) also suppressed miR-26a production by directly binding to a predicted NF-κB binding element in the promoter region of miR-26a. Finally, we observed a negative correlation between NF-κB and miR-26a in human patients with osteoarthritis. Thus, we identified a reciprocal inhibition between miR-26a and NF-κB downstream of non-esterified fatty acid (NEFA) signalling in obesity-related chondrocytes. Our findings provide a potential mechanism linking obesity to cartilage inflammation.

Computer Simulation and Analysis on Flow Characteristics and Distribution Patterns of Polymethylmethacrylate in Lumbar Vertebral Body and Vertebral Pedicle.

This study was designed to analyze the flow and distribution of polymethylmethacrylate (PMMA) in vertebral body through computer simulation. Cadaveric lumbar vertebrae were scanned through electron beam tomography (EBT). The data was imported into Mimics software to build computational model. Vertebral body center and junction of pedicle and vertebral body were chosen as injection points. Silicone oil with viscosity of 100,000 cSt matching with PMMA bone cement was chosen for injection. The flow and distribution of silicone oil were analyzed using Fluent software. In vertebral body, silicone oil formed a circle-like shape centered by injection point on transverse and longitudinal sections, finally forming a sphere-like shape as a whole. Silicone oil diffused along lateral and posterior walls forming a circle-like shape on transverse section centered by injection point in pedicle, eventually forming a sphere-like shape as a whole. This study demonstrated that silicone oil flowed and diffused into a circle-like shape centered by injection point and finally formed a sphere-like shape as a whole in both vertebral body and pedicle. The flow and distribution of silicon oil in computational model could simulate PMMA distribution in vertebral body. It may provide theoretical evidence to reduce PMMA leakage risk during percutaneous vertebroplasty.