Enhancement of surface bioactivity on carbon fiber-reinforced polyether ether ketone via graphene modification.

BACKGROUND AND OBJECTIVE: The modulus of carbon fiber-reinforced polyether ether ketone (CFR-PEEK), a composite containing layers of carbon fiber sheets, can be precisely controlled to match bone. However, CFR-PEEK is biologically inert and cannot promote bone apposition. The objective of this study was to investigate whether graphene modification could enhance the bioactivity of CFR-PEEK. METHODS AND RESULTS: In vitro, the proliferation and differentiation of rat bone marrow stromal cells on scaffolds were quantified via cell-counting kit-8 assay and Western blotting analysis of osteoblast-specific proteins. Graphene modification significantly promoted bone marrow stromal cell proliferation and accelerated induced differentiation into osteogenic lineages compared to cells seeded onto nongraphene-coated CFR-PEEK. An in vivo rabbit extraarticular graft-to-bone healing model was established. At 4, 8, and 12 weeks after surgery, microcomputed tomography analyses and histological observations revealed significantly better microstructural parameters and higher average mineral apposition rates for graphene-modified CFR-PEEK implants than CFR-PEEK implants (P<0.05). van Gieson staining indicated more new bone was formed around graphene-modified CFR-PEEK implants than CFR-PEEK implants. CONCLUSION: Graphene may have considerable potential to enhance the bioactivity and osseointegration of CFR-PEEK implants for clinical applications.

Effects of Artificial Ligaments with Different Porous Structures on the Migration of BMSCs.

Polyethylene terephthalate- (PET-) based artificial ligaments (PET-ALs) are commonly used in anterior cruciate ligament (ACL) reconstruction surgery. The effects of different porous structures on the migration of bone marrow mesenchymal stem cells (BMSCs) on artificial ligaments and the underlying mechanisms are unclear. In this study, a cell migration model was utilized to observe the migration of BMSCs on PET-ALs with different porous structures. A rabbit extra-articular graft-to-bone healing model was applied to investigate the in vivo effects of four types of PET-ALs, and a mechanical test and histological observation were performed at 4 weeks and 12 weeks. The BMSC migration area of the 5A group was significantly larger than that of the other three groups. The migration of BMSCs in the 5A group was abolished by blocking the RhoA/ROCK signaling pathway with Y27632. The in vivo study demonstrated that implantation of 5A significantly improved osseointegration. Our study explicitly demonstrates that the migration ability of BMSCs can be regulated by varying the porous structures of the artificial ligaments and suggests that this regulation is related to the RhoA/ROCK signaling pathway. Artificial ligaments prepared using a proper knitting method and line density may exhibit improved biocompatibility and clinical performance.

Effects of graphene modification on the bioactivation of polyethylene-terephthalate-based artificial ligaments.

The objective of this study was to investigate whether surface coating with graphene could enhance the surface bioactivation of PET-based artificial ligaments to accelerate graft-to-bone healing after anterior cruciate ligament reconstruction. In an in vitro study, the proliferation of MC3T3-E1 cells and their differentiation on the scaffolds were quantified via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and real-time polymerase chain reaction assays. The significantly higher optical-density values and transcription levels of osteoblast-specific genes indicated that graphene modification could promote the proliferation of MC3T3-E1 cells and accelerate their specific differentiation into osteogenic lineages on scaffolds. In an in vivo test, rabbits were used to establish an extra-articular graft-to-bone healing model. At 4, 8, and 12 weeks after surgery, biomechanical tests, microcomputed tomography analysis, and histological observations were performed. The final results demonstrated that the microstructural parameters, the average mineral apposition rate of the bone, and the biomechanical properties of the graphene-coated polyethylene terephthalate (PET)-based artificial ligament (G-PET-AL) group were significantly higher than those of the PET-AL graft group (P < 0.05). The results of Van Gieson staining indicated that in the G-PET-AL group, there was more newly formed bone than there was in the group in which nongraphene-coated PET-ALs were used. In conclusion, graphene exhibits considerable potential for enhancing the surface bioactivation of materials.

[Anterolateral minimally-invasive total hip arthroplasty: a clinical comparative study of 110 cases].

OBJECTIVE: To explore the indications and key points of anterolateral minimally-invasive total hip arthroplasty. METHODS: 110 baseline indexes matched patients admitted for unilateral total hip arthroplasty were randomly assigned to 2 equal groups to undergo surgery through a short anterolateral incision of < or = 10 cm or a standard posterolateral incision. All operations were done by the same surgeon. The demographic data, perioperative indexes, and postoperative function indexes were recorded and statistically analyzed. RESULTS: No significant differences were detected with respect to operation time, abduction angle, anteversion angle, stem alignment, and stem fixation between these 2 groups. The incision length, blood loss, perioperative transfusion, and 100 - mm visual analogue pain scale (VAS) score at the first 24 hours of the anterolateral approach group were (7.49 +/- 0.86) cm, (376.18 +/- 168.30) ml, (410.09 +/- 136.46) ml, and (30.76 +/- 21.77) respectively, all significantly shorter, less, or lower than those of the standard posterolateral approach group [(15.2 +/- 1.8) cm, (605.0 +/- 225.1) ml, (629.5 +/- 232.9) ml, and (50.3 +/- 13.7) respectively, all P < 0.01]. The Harris hip score and Barthel index 3 months after operation of the anterolateral approach group were (83.80 +/- 5.64) and (93.45 +/- 6.37) respectively, both significantly higher than those of the standard posterolateral approach group [(75.0 +/- 7.5) and (94.6 +/- 7.5) respectively, both P < 0.01)], however, there were not significant differences in the Harris hip score and Barthel index 3 years after operation between these 2 groups. CONCLUSIONS: Fewer traumas, less blood loss and rapid recovery can be obtained through this new total hip arthroplasty approach. But experienced doctors and special instruments are prerequisite.

Effect of ovariectomy on BMD, micro-architecture and biomechanics of cortical and cancellous bones in a sheep model.

Osteoporotic/osteopenia fractures occur most frequently in trabeculae-rich skeletal sites. The purpose of this study was to use a high-resolution micro-computed tomography (micro-CT) and dual energy X-ray absorptionmeter (DEXA) to investigate the changes in micro-architecture and bone mineral density (BMD) in a sheep model resulted from ovariectomy (OVX). Biomechanical tests were performed to evaluate the strength of the trabecular bone. Twenty adult sheeps were randomly divided into three groups: sham group (n=8), group 1 (n=4) and group 2 (n=8). In groups 1 and 2, all sheep were ovariectomized (OVX); in the sham group, the ovaries were located and the oviducts were ligated. In all animals, BMD for lumbar spine was obtained during the surgical procedure. BMD at the spine, femoral neck and femoral condyle was determined 6 months (group 1) and 12 months (group 2) post-OVX. Lumbar spines and femora were obtained and underwent BMD scan, micro-CT analysis. Compressive mechanical properties were determined from biopsies of vertebral bodies and femoral condyles. BMD, micro-architectural parameters and mechanical properties of cancellous bone did not decrease significantly at 6 months post-OVX. Twelve months after OVX, BMD, micro-architectural parameters and mechanical properties decreased significantly. The results of linear regression analyses showed that trabecular thickness (Tb.Th) (r=0.945, R2=0.886) and bone volume fraction (BV/TV) (r=0.783, R2=0.586) had strong (R2>0.5) correlation to compression stress. In OVX sheep, changes in the structural parameters of trabecular bone are comparable to the human situation during osteoporosis was induced. The sheep model presented seems to meet the criteria for an osteopenia model for fracture treatment with respect to morphometric and mechanical properties. But the duration of OVX must be longer than 12 months to ensure the animal model can be established successfully.

Treatment of ipsilateral femoral neck and shaft fractures.

OBJECTIVE: To investigate the clinical characteristics, treatment options and causes of misdiagnosis of ipsilateral femoral neck and shaft fractures. METHODS: Among 20 patients with ipsilateral femoral neck and shaft fractures, 19 were treated operatively and 1 was treated conservatively. Sixteen cases of femoral shaft fractures were treated by open reduction and internal fixation with compressive plate, and 2 cases were treated with interlocking intramedullary nailing. Eighteen femoral neck fractures were treated with cannulated screws. Another patient was treated with proximal femoral nail to fix both the neck and shaft. Delayed diagnosis for femoral neck fractures occurred in 2 cases preoperatively. RESULTS: A total of 19 patients were followed up. The follow up period ranged from 5 to 48 months with an average of 15 months. All the fractures were healed. CONCLUSION: For case of femoral shaft fracture caused by high energy injury, an AP pelvic film should be routinely taken. Once the femoral neck fracture is recognized, operative reduction and fixation should be performed in time. Femoral neck and shaft fractures should be fixed separately.

[Effect of insulin-like growth factor-I on cultured articular chondrocytes of rabbits].

OBJECTIVE: To investigate the influence of insulin-like growth factor-I (IGF-I) on biological characteristics of articular chondrocytes cultured in vitro of rabbits. METHODS: Monolayer articular chondrocytes of 4-week old rabbits were cultured in medium with IGF-I, at the concentrations of 3, 10, 30, 100, and 300 ng/ml. The DNA content in cells and glucuronic acid content in matrix were detected on the 2nd, 4th, 6th days after culture. RESULTS: The DNA content in cells and the glucuronic acid content in matrix in articular chondrocytes cultured in medium with IGF-I at concentrations of 3-300 ng/ml were all significantly higher than those in control group (P < 0.01), which reached the peak at the concentrations of 30-100 mg/ml on the 4th day. CONCLUSION: IGF-I could obviously promote the proliferation of articular chondrocytes in vitro, and there exist time-dependent and dose-dependent effect.