Objective To evaluate the feasibility and validity of chondrogenic differentiation of marrow clot after microfracture of bone marrow stimulation combined with bone marrow mesenchymal stem cells (BMSCs)-derived extracellular matrix (ECM) scaffold in vitro. Methods BMSCs were obtained and isolated from 20 New Zealand white rabbits (5-6 months old). The 3rd passage cells were cultured and induced to osteoblasts, chondrocytes, and adipocytes in vitro, respectively. ECM scaffold was manufactured using the 3rd passage cells via a freeze-dying method. Microstructure was observed by scanning electron microscope (SEM). A full-thickness cartilage defect (6 mm in diameter) was established and 5 microholes (1 mm in diameter and 3 mm in depth) were created with a syringe needle in the trochlear groove of the femur of rabbits to get the marrow clots. Another 20 rabbits which were not punctured were randomly divided into groups A (n=10) and B (n=10): culture of the marrow clot alone (group A) and culture of the marrow clot with transforming growth factor β3 (TGF-β3) (group B). Twenty rabbits which were punctured were randomly divided into groups C (n=10) and D (n=10): culture of the ECM scaffold and marrow clot composite (group C) and culture of the ECM scaffold and marrow clot composite with TGF-β3 (group D). The cultured tissues were observed and evaluated by gross morphology, histology, immunohistochemistry, and biochemical composition at 1, 2, 4, and 8 weeks after culture. Results Cells were successfully induced into osteoblasts, chondrocytes, and adipocytes in vitro. Highly porous microstructure of the ECM scaffold was observed by SEM. The cultured tissue gradually reduced in size with time and disappeared at 8 weeks in group A. Soft and loose structure developed in group C during culturing. Chondroid tissue with smooth surface developed in groups B and D with time. The cultured tissue size of groups C and D were significantly larger than that of group B at 4 and 8 weeks (P lt; 0.05); group D was significantly larger than group C in size (P lt; 0.05). Few cells were seen, and no glycosaminoglycan (GAG) and collagen type II accumulated in groups A and C; many cartilage lacunas containing cells were observed and more GAG and collagen type II were synthesized in groups B and D. The contents of GAG and collagen increased gradually with time in groups B and D, especially in group D, and significant difference was found between groups B and D at 4 and 8 weeks (P lt; 0.05). Conclusion The BMSCs-derived ECM scaffold combined with the marrow clot after microfracture of bone marrow stimulation is effective in TGF-β3-induced chondrogenic differentiation in vitro.
Objective To investigate the biomechanics of a novel injectable calcium phosphate cement (CPC) composited by poly (lactic-co-glycolic acid) (PLGA) combined with double-screw fixation in repairing Schatzker II type tibial plateau fracture, so as to provide the mechanical basis for the clinical minimally invasive treatment. Methods Ten matched pairs of proximal tibia specimens were harvested from 10 elderly cadavers to prepare Schatzker II type tibial plateau fracture model. Fracture was fixed by forcing injection of CPC (experimental group) or autologous cancellous bone (control group) combined with double-screw fixation. The samples underwent axial compression on MTS 858 material testing machine to measure the load-displacement, the maximum load, and compressive stiffness. Results The novel CPC had good injectable property at room temperature, which could fill in bone defect fully and permeated into the surrounding cancellous bone. The average bone mineral density of tibial metaphysis was (0.639 ± 0.081) g/cm2 in the experimental group and (0.668 ± 0.083) g/ cm2 in the control group, showing no significant difference (t=1.012, P=0.331). The maximum load in the experimental group [(4 101 ± 813) N] was significantly higher than that in the control group [(692 ± 138) N] (t=3.932, P=0.001). The compressive stiffness was (1 363 ± 362) N/mm in the experimental group and was (223 ± 54) N/mm in the control group, showing significant difference (t=3.023, P=0.013). Conclusion The novel CPC can effectively restore the biomechanical properties of tibilal plateau in repairing Schatzker II type tibial plateau fracture by means of forcing injection combining with double-screw fixation. It could be used as an effective bone substitute in the clinical application.
Objective To explore the application of individualized transiliac crest nail-grafting guide plate prepared by computer-aided design and three-dimensional (3D) printing technology in deep pelvic external fixator implantation. Methods Five patients with pelvic fractures were collected between May 2017 and February 2018. There were 4 females and 1 male with an average age of 52 years (range, 29-68 years). Pelvic fractures were classified as type B in 3 cases and type C in 2 cases by Tile classification. The interval between injury and operation was 6-14 days (mean, 9 days). The preoperative CT images of pelvic fractures were collected. The data was reconstructed by 3D imaging reconstruction workstation. An individualized transiliac crest nail-grafting guide plate was designed on the virtual 3D model. The individualized transiliac crest nail-grafting guide plate and the solid pelvic model were produced with the 3D printing technology. The individualized transiliac crest nail-grafting guide plate was used for intraoperative deep pin position on iliac crest after the preoperative simulation. The follow-up CT scans were used to determine the differences in distance from anterior superior iliac spine, convergence angle, and caudal angle between the preoperative plan and postoperative measurement. Results During the operation, the individualized transiliac crest nail-grafting guide plate was used to guide the placement of 20 pins. X-ray film and CT examination showed that all pins were well positioned. The average depth of pins was 83.16 mm (range, 70.13-100.53 mm). Fitted 3D reconstruction images showed that the entry point and orientation of the pins were all consistent with preoperative schemes. Compared with the planned nail path, there was no significant difference in the distance from anterior superior iliac spine, convergence angle, and caudal angle in the actual nail path (P>0.05). No loosening and rupture of pin, no damage of blood vessels and nerve, and shallow or deep infection occurred during 3 months follow-up, and the incisions healed by first intention. All patients were satisfied with the treatment process. The ranges of motion of hip and knee were normal, and the visual analogue scale (VAS) score was 0-3 (mean, 0.5). Conclusion The individualized transiliac crest nail-grafting guide plate technique is the improvement of traditional technique. It can increase accuracy and effective depth of pin position, enable patients to obtain pelvic mechanical stability quickly after operation, and reduce the risk of complications related to nail path.