Vortex evolution patterns for flow of dilute polymer solutions in confined microfluidic cavities.

Flow instability in confined cavities has attracted extensive interest due to its significance in many natural and engineering processes. It also has applications in microfluidic devices for biomedical applications including flow mixing, nanoparticle synthesis, and cell manipulation. The recirculating vortex that characterizes the flow instability is regulated by the fluid rheological properties, cavity geometrical characteristics, and flow conditions, but there is a lack of quantitative understanding of how the vortex evolves as these factors change. Herein, we experimentally study the flow of dilute polymer solutions in confined microfluidic cavities and focus on a quantitative characterization of the vortex evolution. Three typical patterns of vortex evolution are identified in the cavity flow of dilute polymer solutions over a wide range of flow conditions. The geometrical characteristics of the cavity are found to have little effect on the patterns of vortex evolution. The geometry-independent patterns of vortex evolution provide us an intuitive paradigm, from which the interaction and competition among inertial, elastic and shear-thinning effects in these cavity-induced flow instabilities are clarified. These results extend our understanding of the flow instability of complex fluids in confined cavities, and provide useful guidelines for the design of cavity-structured microfluidic devices and their applications.

Tranexamic versus aminocaproic acids in patients with total hip arthroplasty: a retrospective study.

BACKGROUND: Recently, tranexamic acid (TXA) and epsilon aminocaproic acid (EACA) have been applied in total hip arthroplasty (THA). However, doubts in clinicians' minds about which medicine is more efficient and economical in THA need to be clarified. Therefore, this study compared the efficacy and cost of the intraoperative administration of TXA and EACA per surgery in decreasing perioperative blood transfusion rates in THA. METHODS:  This study enrolled patients who underwent THA between January 2019 to December 2020. A total of 295 patients were retrospectively divided to receive topical combined with intravenous TXA (n = 94), EACA (n = 97) or control (n = 104). The primary endpoints included transfusions, estimated perioperative blood loss, cost per patient and the drop in the haemoglobin and haematocrit levels. RESULTS: Patients who received EACA had greater total blood loss, blood transfusion rates, changes in HGB levels and mean cost of blood transfusion per patient (P < 0.05) compared with patients who received TXA. In addition, both TXA and EACA groups had significantly fewer perioperative blood loss, blood transfusion, operation time and changes in haemoglobin and haematocrit levels than the control group (P < 0.05). Cost savings in the TXA and EACA groups were 736.00 RMB and 408.00 RMB per patient, respectively. CONCLUSIONS: The application of perioperative antifibrinolytics notably reduces the need for perioperative blood transfusions. What's more, this study demonstrated that TXA is superior to EACA for decreasing blood loss and transfusion rates while at a lower cost per surgery. These results indicate that TXA may be the optimum antifibrinolytics for THA in Chinese area rather than EACA.

The 2021 Association Research Circulation Osseous Classification for Early-Stage Osteonecrosis of the Femoral Head to Computed Tomography-Based Study.

BACKGROUND: The Association Research Circulation Osseous developed a novel classification for early-stage (precollapse) osteonecrosis of the femoral head (ONFH). We hypothesized that the novel classification is more reliable and valid when compared to previous 3 classifications: Steinberg, modified Kerboul, and Japanese Investigation Committee classifications. METHODS: In the novel classification, necrotic lesions were classified into 3 types: type 1 is a small lesion, where the lateral necrotic margin is medial to the femoral head apex; type 2 is a medium-sized lesion, with the lateral necrotic margin being between the femoral head apex and the lateral acetabular edge; and type 3 is a large lesion, which extends outside the lateral acetabular edge. In a derivation cohort of 40 early-stage osteonecrotic hips based on computed tomography imaging, reliabilities were evaluated using kappa coefficients, and validities to predict future femoral head collapse by chi-squared tests and receiver operating characteristic curve analyses. The predictability for future collapse was also evaluated in a validation cohort of 104 early-stage ONFH. RESULTS: In the derivation cohort, interobserver reliability (k = 0.545) and intraobserver agreement (63%-100%) of the novel method were higher than the other 3 classifications. The novel classification system was best able to predict future collapse (P < .05) and had the best discrimination between non-progressors and progressors in both the derivation cohort (area under the curve = 0.692 [0.522-0.863], P < .05) and the validation cohort (area under the curve = 0.742 [0.644-0.841], P = 2.46 × 10-5). CONCLUSION: This novel classification is a highly reliable and valid method of those examined. Association Research Circulation Osseous recommends using this method as a unified classification for early-stage ONFH. LEVEL OF EVIDENCE: Level III, diagnostic study.

The 2019 Revised Version of Association Research Circulation Osseous Staging System of Osteonecrosis of the Femoral Head.

BACKGROUND: The Association Research Circulation Osseous (ARCO) presents the 2019 revised staging system of osteonecrosis of the femoral head (ONFH) based on the 1994 ARCO classification. METHODS: In October 2018, ARCO established a task force to revise the staging system of ONFH. The task force involved 29 experts who used a web-based survey for international collaboration. Content validity ratios for each answer were calculated to identify the levels of agreement. For the rating queries, a consensus was defined when more than 70% of the panel members scored a 4 or 5 rating on a 5-point scale. RESULTS: Response rates were 93.1%-100%, and through the 4-round Delphi study, the 1994 ARCO classification for ONFH was successfully revised. The final consensus resulted in the following 4-staged system: stage I-X-ray is normal, but either magnetic resonance imaging or bone scan is positive; stage II-X-ray is abnormal (subtle signs of osteosclerosis, focal osteoporosis, or cystic change in the femoral head) but without any evidence of subchondral fracture, fracture in the necrotic portion, or flattening of the femoral head; stage III-fracture in the subchondral or necrotic zone as seen on X-ray or computed tomography scans. This stage is further divided into stage IIIA (early, femoral head depression ≤2 mm) and stage IIIB (late, femoral head depression >2 mm); and stage IV-X-ray evidence of osteoarthritis with accompanying joint space narrowing, acetabular changes, and/or joint destruction. This revised staging system does not incorporate the previous subclassification or quantitation parameters, but the panels agreed on the future development of a separate grading system for predicting disease progression. CONCLUSION: A staging system has been developed to revise the 1994 ARCO classification for ONFH by an expert panel-based Delphi survey. ARCO approved and recommends this revised system as a universal staging of ONFH.

Uncontacted tire explosion causing trauma to bilateral lower extremities: A case report.

It is uncommon for tire explosion related injuries on the lower extremity. The bilateral lower extremities were injured by tire explosion when the patient was seated in a bus. She sustained an open fracture with partial bone loss in the right calcaneus (a comminuted fracture in the right ankle joint) and a closed comminuted fracture in the left tibia and fibula. This damage was caused by uncontacted tire explosion, thanks to a thick floor between the exploded tire and the patient's feet. This type of injury on lower extremity caused by uncontacted tire explosion was uncommon.

Core decompression treatment of early-stage osteonecrosis of femoral head resulted from venous stasis or artery blood supply insufficiency.

BACKGROUND: The objective of this study was to explore the therapeutic effect of core decompression on different hemodynamics changes associated with osteonecrosis of the femoral head (ONFH). METHODS: A total of 67 patients with 76 hips suffering from ONFH (Arco stage I-IIC) received core decompression surgical procedure. Radiographic, magnetic resonance imaging, and digital subtraction angiography examinations were performed before operation. Radiographic and magnetic resonance imaging follow-ups were also performed after 12, 24, and 60 mo of operation. Clinical follow-ups were performed using the Harris Hip Score (HHS) for an average period of 5 y postoperation. RESULTS: The mean follow-up time ranged from 2-8 y with an average of 5 y. Two hips were lost during follow-up. Successful clinical efficacy (HHS ≥80) was achieved in 91.9% (68/74) of the hips. Six hips had conversion to total hip arthroplasty (THA), one hip had venous stasis, and five hips had both vein stasis and artery blood supply insufficiency. The mean HHS for the patients who did not have conversion to THA improved from 65 ± 3.5 to 89 ± 3.6 (mean ± standard deviation). Twenty-six stage I hips (100%), 22 of 23 stage IIA hips (95.7%), 13 of 15 stage IIB hips (86.7%), and 8 of 10 stage IIC hips (80%) had successful outcomes with no surgical complications. Kaplan-Meier survival analysis showed that 8-y survival rate was significantly different between stage I and stage IIC (THA as an end point; P < 0.001). CONCLUSIONS: In patients with early-stage ONFH resulted from only venous stasis, core decompression led to a significant improvement in HHS and 8-y survival rate. However, the long-term efficacy for ONFH associated with artery blood supply insufficiency was not encouraging. Therefore, preoperative digital subtraction angiography is necessary before performing core decompression.

Inhibition of UDP-Glucuronosyltransferases (UGTs) Activity by constituents of Schisandra chinensis.

Structure-activity relationship for the inhibition of Schisandra chinensis's ingredients toward (Uridine-Diphosphate) UDP-glucuronosyltransferases (UGTs) activity was performed in the present study. In vitro incubation system was employed to screen the inhibition capability of S. chinensis's ingredients, and in silico molecular docking method was carried out to explain possible mechanisms. At 100 µM of compounds, the activity of UGTs was inhibited by less than 90% by schisandrol A, schisandrol B, schisandrin, schisandrin C, schisantherin A, gomisin D, and gomisin G. Schisandrin A exerted strong inhibition toward UGT1A1 and UGT1A3, with the residual activity to be 7.9% and 0% of control activity. Schisanhenol exhibited strong inhibition toward UGT2B7, with the residual activity to be 7.9% of control activity. Gomisin J of 100 µM inhibited 91.8% and 93.1% of activity of UGT1A1 and UGT1A9, respectively. Molecular docking prediction indicated different hydrogen bonds interaction resulted in the different inhibition potential induced by subtle structure alteration among schisandrin A, schisandrin, and schisandrin C toward UGT1A1 and UGT1A3: schisandrin A > schisandrin > schisandrin C. The detailed inhibition kinetic evaluation showed the strong inhibition of gomisin J toward UGT1A9 with the inhibition kinetic parameter (Ki ) to be 0.7 µM. Based on the concentrations of gomisin J in the plasma of the rats given with S. chinensis, high herb-drug interaction existed between S. chinensis and drugs mainly undergoing UGT1A9-mediated metabolism. In conclusion, in silico-in vitro method was used to give the inhibition information and possible inhibition mechanism for S. chinensis's components toward UGTs, which guide the clinical application of S. chinensis.

Extracellular vesicles derived from mesenchymal stem cells mediate extracellular matrix remodeling in osteoarthritis through the transport of microRNA-29a.

BACKGROUND: Knee osteoarthritis (KOA) is a common orthopedic condition with an uncertain etiology, possibly involving genetics and biomechanics. Factors like changes in chondrocyte microenvironment, oxidative stress, inflammation, and immune responses affect KOA development. Early-stage treatment options primarily target symptom relief. Mesenchymal stem cells (MSCs) show promise for treatment, despite challenges. Recent research highlights microRNAs (miRNAs) within MSC-released extracellular vesicles that can potentially promote cartilage regeneration and hinder KOA progression. This suggests exosomes (Exos) as a promising avenue for future treatment. While these findings emphasize the need for effective KOA progression management, further safety and efficacy validation for Exos is essential. AIM: To explore miR-29a's role in KOA, we'll create miR-29a-loaded vesicles, testing for early treatment in rat models. METHODS: Extraction of bone marrow MSC-derived extracellular vesicles, preparation of engineered vesicles loaded with miR-29a using ultrasonication, and identification using quantitative reverse transcription polymerase chain reaction; after establishing a rat model of KOA, rats were randomly divided into three groups: Blank control group injected with saline, normal extracellular vesicle group injected with normal extracellular vesicle suspension, and engineered extracellular vesicle group injected with engineered extracellular vesicle suspension. The three groups were subjected to general behavioral observation analysis, imaging evaluation, gross histological observation evaluation, histological detection, and immunohistochemical detection to compare and evaluate the progress of various forms of arthritis. RESULTS: General behavioral observation results showed that the extracellular vesicle group and engineered extracellular vesicle group had better performance in all four indicators of pain, gait, joint mobility, and swelling compared to the blank control group. Additionally, the engineered extracellular vesicle group had better pain relief at 4 wk and better knee joint mobility at 8 wk compared to the normal extracellular vesicle group. Imaging examination results showed that the blank control group had the fastest progression of arthritis, the normal extracellular vesicle group had a relatively slower progression, and the engineered extracellular vesicle group had the slowest progression. Gross histological observation results showed that the blank control group had the most obvious signs of arthritis, the normal extracellular vesicle group showed signs of arthritis, and the engineered extracellular vesicle group showed no significant signs of arthritis. Using the Pelletier gross score evaluation, the engineered extracellular vesicle group had the slowest progression of arthritis. Results from two types of staining showed that the articular cartilage of rats in the normal extracellular vesicle and engineered extracellular vesicle groups was significantly better than that of the blank control group, and the engineered extracellular vesicle group had the best cartilage cell and joint surface condition. Immunohistochemical detection of type II collagen and proteoglycan showed that the extracellular matrix of cartilage cells in the normal extracellular vesicle and engineered extracellular vesicle groups was better than that of the blank control group. Compared to the normal extracellular vesicle group, the engineered extracellular vesicle group had a better regulatory effect on the extracellular matrix of cartilage cells. CONCLUSION: Engineered Exos loaded with miR-29a can exert anti-inflammatory effects and maintain extracellular matrix stability, thereby protecting articular cartilage, and slowing the progression of KOA.

Decreased synovial fluid omentin-1 concentrations reflect symptomatic severity in patients with knee osteoarthritis.

The aim of this study was to measure omentin-1 concentrations in serum and synovial fluid (SF) of knee osteoarthritis (OA) patients and to investigate their correlation with patient-reported symptomatic severity. We enrolled 263 knee OA patients and 62 healthy controls. We collected Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores from OA patients and measured omentin-1 concentrations in serum and SF by enzyme-linked immunosorbent assay (ELISA). Our results demonstrated that omentin-1 concentrations in SF but not serum were independently and negatively correlated with self-reported greater pain and physical disability in OA patients. Omentin-1 in SF might serve as a potential biomarker for reflecting the symptomatic severity of OA.

[Effects of different stress force stimulations on the expression of vascular endothelial growth factor in Beagle dogs in the repairing process of osteonecrosis of the femoral head].

OBJECTIVE: To explore the changes and its significance of the expression of vascular endothelial growth factor (VEGF) protein and messenger RNA in the Beagle dogs femoral head during the repairing process of the osteonecrosis of femoral head (ONFH) under different stress force stimulations. METHODS: Twenty-four Beagle dogs were selected to establish the model of ONFH through the method of liquid nitrogen cryopreservation. In the mean time, the necrotic femoral heads stimulated by different stress forces were enrolled into 3 groups: group B (low stress force stimulation group), group C (high stress force stimulation group) and group D (average stress force stimulation group). Group A was control group. The beagle dogs were sacrificed at Weeks 4 and 8 post-operation. The changes of femoral head were evaluated by histological observation, immunohistochemical staining and quantitative reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Histological observation showed that articular cartilage, morphology and structure of trabecular bone in group D was better than those of groups B and C. Immunohistochemistry revealed that the VEGF protein positive staining in group D was significantly higher than that in groups A, B and C at Weeks 4 and 8 post-operation. The expression of VEGF mRNA in group D was much more than that in groups A, B and C by RT-PCR. And the expression was higher at Week 8 post-operation. CONCLUSION: Proper stress force stimulation can effectively promote the expression of VEGF protein and messenger RNA in necrotic femoral head of Beagle dogs and boost angiogenesis to improve the blood supply of necrotic femoral head so as to accelerate the repairing process of ONFH.

Relationship Between Blood Flow and Collapse of Nontraumatic Osteonecrosis of the Femoral Head.

BACKGROUND: To investigate the collapse mechanism in osteonecrosis of the femoral head (ONFH), we studied the relationship between the femoral head (FH) blood circulation changes and the collapse area histomorphometry characteristics. METHODS: A technique involving microvascular perfusion of the FH in vitro to reconstruct the vessels in the FH at different stages of nontraumatic ONFH (40 cases). In addition, we also examined the histomorphometry characteristics in the collapse area during ONFH at different stages using the hard tissue section technique. To investigate the blood supply changes in the FH on pathological involved in the FH collapse process. RESULTS: The results showed that in all FHs, the collapse area always involved the margin of the necrotic lesion of the lateral column. Histologically, the fracture occurred between the thickened and necrotic trabeculae at the junction. We found that the collapse started at the lateral column of the FH in the necrotic lesion and that the lateral column was ischemic, which caused the FH to begin to collapse. CONCLUSIONS: Based on the above findings, the relationship between associations of the blood circulation to the collapse showed that if a portion of the blood supply of the lateral column (the superior retinacular artery) was preserved, the prognosis of the natural progression of the diseases was improved, the collapse rate was low and collapse occurred later. The blood circulation of artery in the lateral column was good, and the FH maintained an intact shape even if the internal region was ischemic. Therefore, we can predict the collapse of the FH by measuring the blood flow in the lateral area of the FH, thus providing guidance for the selection of FH-preserving clinical therapy in young and middle-aged patients. CLINICAL RELEVANCE: This work provides a proof of how to predict the collapse of the FH by measuring the blood flow, providing guidance for FH-preserving clinical therapy in young and middle-aged patients.

In vivo biocompatibility evaluation of Zn-0.05Mg-(0, 0.5, 1wt%)Ag implants in New Zealand rabbits.

Bio-absorbable Zn alloys have been attractive replacements for the traditionally permanent implants due to their reasonable mechanical strength and elongation, degradation rate, and biocompatibility. The hybridization addition of Mg and Ag elements could greatly improve the mechanical properties and antibacterial ability of Zn, respectively. In the present paper, in vivo biocompatibility for the Zn-0.05Mg-(0, 0.5, 1 wt%) Ag implants in New Zealand rabbit was qualitatively evaluated during the implantation periods of 4, 12, and 24 weeks. The blood serum biochemical parameters and in vivo integrity of the implants in the live rabbits were monitored by using clinical chemistry analyzing and X-ray radiographic imaging techniques during the implantation process, respectively. There is no great difference in the serum biochemical indicator between the implanted rabbits and the control group. Especially the levels of serum Zn and serum Mg normalize after implantation of 24 weeks. The interfacial adherence between the implants and newly formed bones, and the histopathological morphology of heart, liver, and kidney were observed morphologically under the microscope. The new bones formed and grew surrounding the implants after 12 weeks' post-operation, which were well joined with the original cortical bones after post-implantation of 24 weeks. The heart, liver and kidney were not negatively influenced as evidenced from the serum biochemical indicators and morphologies of the tissues. Zn-0.05Mg-(0, 0.5, 1 wt%) Ag alloys are proved to be in vivo biocompatible and potential candidates for the biodegradable medical implants.

Ligand capping effect for dye solar cells with a CdSe quantum dot sensitized ZnO nanorod photoanode.

We report a quantum dot sensitized solar cell (QDSSC) with a thioglycolic acid (TGA) capped CdSe quantum dot (QD) sensitized ZnO nanorod photoanode. As revealed by UV-Vis absorption spectrum and transmission electron microscopy, the quantum dots can be effectively adsorbed onto ZnO nanorods. By studying the emission decay, the quenching of the CdSe QDs by ZnO nanorod was verified, and an electron transfer (from QD to ZnO) rate constant of 1 x 10(8) s(-1) was obtained. The efficiency of the as-prepared QDSSC was 0.66% and an incident power conversion efficiency of 22% at 400 nm was achieved.

[Gait analysis after anterior cruciate ligament reconstruction with different methods].

OBJECTIVE: To examine and compare the gait patterns of subjects with hamstring and patellar tendon graft reconstructions of anterior cruciate ligament (ACL). METHODS: Three groups were compared: 19 patellar tendon anterior cruciate ligament reconstruction patients (a mean of 11.8 weeks after injury), 19 hamstring tendon anterior cruciate ligament reconstruction patients (a mean of 10.4 weeks after injury) and 19 matched controls. Gait analysis was performed using the DorealSoft DVMC-8801 three-dimensional motion capture system. Kinematic data were recorded for the lower limb prior to and 3, 6, 9 and 12 months after ACL reconstructive surgery. Each subject was asked to walk on a motorized treadmill with different slopes and perform-after 6 minutes of familiarization time- at least 2 minutes of walking at a constant speed of 1.9 km/h. RESULTS: All the ACL-deficient patients exhibited a quadriceps avoidance pattern prior to and 3 months post-operation. In the operated individuals, the spatial-temporal parameters and the knee angle had already regained a normal pattern for the ACL-deficient limb during gait at 6 months post-operation. However, the angular acceleration showed no significant statistical difference with the values of healthy control group at just 9 months post-operation. The flexion angular acceleration at 15 degrees treadmill was significantly smaller than that in the hamstring tendon group and the extension angular acceleration was significantly smaller than that in the patellar tendon group at 6 months post-operation. CONCLUSION: ACL surgical repair significantly alters the lower-extremity gait patterns and the establishment of pre-injury gait patterns takes at least 9 months to occur. The graft-specific differences in knee biomechanics after anterior cruciate ligament reconstruction appear to be related with the donor site.

[Treatment of non-traumatic avascular talar necrosis by transposition of vascularized cuneiform bone flap plus iliac cancellous bone grafting].

OBJECTIVE: To evaluate the outcome of cancellous bone grafting plus iliac cancellous bone in the treatment of non-traumatic avascular talar necrosis. METHODS: Twenty patients, 14 males and six females, eight at stage II, ten at stage III and three at stage IV according to the modified Ficat & Arlet necrosis classification system, were treated with vascularized bone flap from January 2000 to June 2005. RESULTS: All patients were followed up for a mean of 37 months (range: 14 to 68 months). The clinical function outcome evaluated by Kenwright criteria were excellent in 8 cases, good in 10 cases, fair in 1 case and poor in 1 case. Clinical symptom was completely or partially relieved. The necrotic area was filled with newly formed bone and the excellent-to-good rate was 90%. CONCLUSION: Transposition of vascularized cuneiform bone flap plus iliac cancellous bone grafting may be an ideal therapeutic method for non-traumatic avascular talar necrosis. And the clinical outcome is satisfactory.

Magnesium and vitamin C supplementation attenuates steroid-associated osteonecrosis in a rat model.

Magnesium (Mg)-based biometal attracts clinical applications due to its biodegradability and beneficial biological effects on tissue regeneration, especially in orthopaedics, yet the underlying anabolic mechanisms in relevant clinical disorders are lacking. The present study investigated the effect of magnesium (Mg) and vitamin C (VC) supplementation for preventing steroid-associated osteonecrosis (SAON) in a rat experimental model. In SAON rats, 50 mg/kg Mg, or 100 mg/kg VC, or combination, or water control was orally supplemented daily for 2 or 6 weeks respectively. Osteonecrosis was evaluated by histology. Serum Mg, VC, and bone turnover markers were measured. Microfil-perfused samples prepared for angiography and trabecular architecture were evaluated by micro-CT. Primary bone marrow cells were isolated from each group to evaluate their potentials in osteoblastogenesis and osteoclastogenesis. The mechanisms were tested in vitro. Histological evaluation showed SAON lesions in steroid treated groups. Mg and VC supplementation synergistically reduced the apoptosis of osteocytes and osteoclast number, and increased osteoblast surface. VC supplementation significantly increased the bone formation marker PINP, and the combination significantly decreased the bone resorption marker CTX. TNFα expression and oxidative injury were decreased in bone marrow in Mg/VC/combination group. Mg significantly increased the blood perfusion in proximal tibia and decreased the leakage particles in distal tibia 2 weeks after SAON induction. VC significantly elevated the osteoblast differentiation potential of marrow cells and improved the trabecular architecture. The combination supplementation significantly inhibited osteoclast differentiation potential of marrow cells. In vitro study showed promoting osteoblast differentiation effect of VC, and anti-inflammation and promoting angiogenesis effect of Mg with underlying mechanisms. Mg and VC supplementation could synergistically alleviate SAON in rats, indicating great translational potentials of metallic minerals for preventing SAON.

[Treatment for osteonecrosis of femoral head by hVEGF-165 gene modified marrow stromal stem cells under arthroscope].

OBJECTIVE: To understand the biological characteristics and osteogenic potential of hVEGF-165 gene modified marrow stromal stem cells and investigate the effect and value of treatment for osteonecrosis of femoral head by hVEGF-165 gene modified marrow stromal stem cells under arthroscope. METHODS: rAAV-2-hVEGF-165 plasmids were extracted and transfected into rabbit marrow stromal stem cells. hVEGF-165 mediated by adeno-associated virus (AAV) was used to transfect rMSCs. The transfection efficiency was detected with enhanced green fluorescent protein under fluorescence microscope. hVEGF-165 mediated by adeno-associated virus (AAV) was used to transfect rMSCs. Virus transfection stayed overnight after 90% cell converged. MOI was 105. The transcription and expression of hVEGF-165 protein expression were detected by RT-PCR and Western blot. The necrotic bone was emptied and then MSCs were implanted under arthroscope. The histology of femoral head was inspected at postoperative 2 - 8 weeks. RESULTS: The expression of hVEGF-165 gene could be found distinctly in the transfected rabbit MSCs and hVEGF-165 protein in the supernatants of transfected cell cultures. The transfection efficiency of adeno-associated virus (AAV) transfected rMSCs was 70%. And rAAV-2-hVEGF-165 transfected rMSCs achieved an effective expression by RT-PCR and Western blot. hVEGF-165 could be found after a 48-hour transfection and peaked at Day 10. Immunohistochemical detection showed that the implanted rMSCs was positive at Week 2 and strong positive at Week 8. The compressive strength of the hVEGF-165 gene group approached that of normal control. CONCLUSION: hVEGF-165 gene transfected rabbit MSCs can express hVEGF-165 with highly biological activity. It provides provided a basis for employing hVEGF-165 gene and MSCs based gene therapy for ONFH repairing and regeneration. rAAV-2-hVEGF-165/MSCs may be implanted accurately under arthroscope. Implantation of human BMP-2 gene transfected BMSCs can repair early-stage experimental femoral head necrosis.

[Treatment of early osteonecrosis of femoral head by core decompression and autograft of mesenchymal stem cell cultured in vitro under arthroscopy: experiment with rabbits].

OBJECTIVE: To observe the therapeutic effect of core decompression and autograft of mesenchymal stem cells (MSCs) cultured in vitro under arthroscopy in treatment of early osteonecrosis of femoral head. METHODS: Thirty-six rabbits were made into models of early osteonecrosis of femoral head of the right leg, and then randomly divided into 3 equal groups: Group A group as control group, Group B group undergoing simple core decompression under arthroscopy by clearing out of necrotic bone, and Group C undergoing core decompression and implantation of MSCs. Four and 8 weeks later 6 rabbits from each group underwent roentgenography and then were killed with their femoral heads taken out to undergo histological examination. RESULTS: Four weeks later new bone was evident in the implantation field of Group C while fibrous tissues were evident in the femoral head of Group B. Pathological examination showed regular shape and normal density of femoral head in Group C and irregular shape and low density of femoral head in Group B. X-ray photograph 8 weeks after treatment showed that the femoral head articular surface of Group A collapsed, uneven density and defect of spongy bone were seen in Group B, and the shape of femoral head of Group C was regular without collapse and the original defect had been repaired. CONCLUSION: With strong osteogenic function, MSCs improve the repair of ischemic necrosis of femoral head and can be used in treatment of early osteonecrosis of femoral head via core decompression and autograft of MSCs cultured in vitro under arthroscopy.

[Restoration of segmental bone defect by calcium sulfate pellet: experiment with rabbit].

OBJECTIVE: To compare the effects of different calcium sulfate pellets made by different methods in treating segmental defect of bone. METHODS: Eighty New Zealand white rabbits underwent cutting off a segment in the middle part of radius so as to establish models of radial segmental defect, and than were divided into 4 groups: Group A as control group, Group B with calcium sulfate pellet made by routine method implanted into the defect, Group C with chitosan coated pressed calcium sulfate pellet implanted into the defect, and Group D with chitosan coated pressed calcium sulfate pellet combined with recombinant human bone morphogenetic protein (rhBMP)-2 implanted into the defect: X-ray photography was done every 4 weeks to observe the new bone formation. Four, 8, and 12 weeks 5 rabbits from each group were killed. The defect segments with parts of normal bone at both ends were cut off to undergo fluorescence microscopy and biomechanic three point bending test. RESULTS: X-ray photography and histological examination showed that new bone formation of cortex and reconstruction of marrow cavity were seen in Groups D and C, especially in Group D. The new bone mineralization rate of Group D was significantly higher than that of Group C (P<0.05) which was significantly higher than that of Group B (P<0.01). The anti-bending strength ratio of Group D was (47.5%+/-2.1%, significantly higher than that of Group C [(39.6+/-1.7)%, F=125.3, P<0.01], and the anti-bending strength ratios of Groups D and C were both significantly higher than those of Groups B and A [(23.6+/-3.3)% and (21.3+/-2.7)%]. CONCLUSION: Chitosan coated pressed calcium sulfate pellet shows relatively higher anti-bending strength and slightly slower resorption that closely coincide with the growth rate of new bone. It can be used to restore segmental bone defect, and particularly when combined with rhBMP-2.

[Gait analysis associated with anterior cruciate ligament reconstruction].

OBJECTIVE: To determine how selected gait parameters, measured by three-dimensional To determine how selected gait parameters, measured by three-dimensional motion capture system, may change as a result of anterior cruciate ligament (ACL) deficiency and following ACL reconstruction. METHODS: The study was performed on 29 ACL-deficient subjects prior to and at 3, 6, 9 and 12 months after ACL reconstructive surgery by the four stranded hamstring tendon technique. The group was examined at an average of 2.6 months after injury (range: 2 weeks-16 months). But at presurgery, gait analysis was performed using the DorealSoft DVMC-8801 three-dimensional motion capture system. Kinematic data were recorded for the lower extremities. The results obtained from the injured subjects were compared with those of 58 individuals without ACL damage. Each subject was asked to walk on a motorized treadmill (ECON USA) with different slopes and perform-after a 6 minute familiarization time-at least 2 minutes of walking at a constant speed of 1.9 km/h. RESULTS: The ACL-deficient patients exhibited a quadriceps avoidance pattern prior to and at 3 months post-surgery. In the operated individuals, the spatial-temporal parameters and the knee angle had already regained a normal pattern for the ACL-deficient extremity during gait at 6 months post-surgery. However, the relative ACL movement parameter-which describes the tibial translation into the direction of ACL-and the angular acceleration showed no significant statistical difference as compared with the values of healthy control group at just 9 months post-surgery. CONCLUSION: The ACL surgical repair significantly alters lower-extremity gait patterns, and that the establishment of pre-injury gait patterns takes at least 9 months to occur. 3D gait analysis for assessment of patients undergoing anterior cruciate ligament reconstruction surgery can precisely reflect knee biomechanical changes, and assist to explore optimal treatment approach and postoperative rehabilitation methods.