ABSTRACT
BACKGROUND:Nano-hydroxyapatite has excellent biocompatibility, biological activity, and modifiability, but the synthesized nano-hydroxyapatite has a high specific surface energy, which makes it agglomerate in solution. OBJECTIVE: To compare the effects of ultrasound and different dispersants on the aggregation, cytotoxicity and intracellular distribution of nano-hydroxyapatite. METHODS: Needle like nano-hydroxyapatite was prepared by chemical precipitation method, and kept for further use after high pressure sterilization. Different concentrations of dispersant sodium hexametaphosphate (0, 0.25, 0.5, 1, 2 mmol/L), sodium citrate (0, 0.25, 0.5, 1, 2 mmol/L), sodium polymethacrylate (0%, 0.0625%, 0.125%, 0.25%, 0.5%) were co-cultured with MC3T3E1 cells. Cell proliferation was detected by CCK-8 assay. The appropriate concentration of dispersant was screened for subsequent experiments. The nano-hydroxyapatite solution was divided into five groups: the control group was not dispersed; and the remaining four groups were subjected to ultrasonic dispersant, 1 mmol/L sodium hexametaphosphate dispersant, 1 mmol/L sodium citrate dispersant, and 0.125% sodium polymethacrylate dispersant. The aggregate size of nano-hydroxyapatite was detected. The hydroxyapatite was treated with ultrasound, 1 mmol/L sodium hexametaphosphate, 1 mmol/L sodium citrate, and 0.125% sodium polyacrylate dispersants and then co-cultured with MC3T3E1 cells. Undispersed nano-hydroxyapatite co-cultured with MC3T3E1 cells was considered as control. Cell proliferation was detected by CCK-8 assay. At 1 day after culture, the distribution of nano-hydroxyapatite was observed by transmission electron microscope. RESULTS AND CONCLUSION: (1) Sodium hexametaphosphate at a concentration of 1 mmol/L and lower had no obvious cytotoxicity. Sodium citrate at 0.25-2 mmol/L had no obvious cytotoxicity. Sodium polymethacrylate at different concentrations had certain cytotoxicity in time-and concentration-dependent manners. Subsequent experiments selected 1 mmol/L sodium hexametaphosphate, 1 mmol/L sodium citrate, and 0.125% sodium polyacrylate for dispersion treatment. (2) All three dispersants significantly reduced the agglomeration size of nano-hydroxyapatite, and sodium hexametaphosphate had the best dispersion effect. (3) The dispersion method and the addition of dispersant could significantly affect the biological function of nano-hydroxyapatite. Sodium citrate promoted the proliferation of cells co-cultured with nano-hydroxyapatite. Ultrasound and sodium polymethacrylate inhibited proliferation of cells co-cultured with nano-hydroxyapatite. (4) Transmission electron microscopy showed that in the control group and the ultrasound group, large agglomerates of nano-hydroxyapatite existed inside and outside the cell; the nano-hydroxyapatite dispersed by the three dispersants also had agglomeration, but the size of the agglomeration was significantly smaller. Among them, the nano-aggregation size of the sodium hexametaphosphate group was the smallest. Some nanoparticles were wrapped in a double-layer membrane in the cell to form a structure similar to “small vacuoles”. (5) The results show that the commonly used dispersants themselves have certain cytotoxicity, and the addition of dispersants will significantly reduce the agglomeration size of nano-hydroxyapatite and its intracellular distribution, and affect cell proliferation.
ABSTRACT
Objective:To investigate the oncological efficacy and functional evaluation of total elbow arthroplasty (TEA) for the reconstruction of tumor around elbow joint.Methods:A retrospective case series study was made on the clinical data of 26 patients who underwent total elbow joint replacement after tumor resection in Beijing Jishuitan Hospital from June 1988 to June 2019. According to the inclusion and exclusion criteria, 23 patients were enrolled in the final study, there were 14 males and 9 females, the mean and median age was 37.6±19.9 and 35.0 years respectively. 23 patients included 3 cases of giant cell tumor, 4 cases of metastatic cancer, 4 cases of Ewing's sarcoma, 2 cases of osteosarcoma, 2 cases of aneurysmal bone cyst, 1 angiosarcoma, 1 primary malignacy in giant cell tumor, 1 low-grade central osteosarcoma, 1 parosteosarcoma, 1 synovial sarcoma, 1 plasma cell myeloma, 1 tendon sheath giant cell tumor and 1 case of mixed tumor. There were 6 cases of benign tumor, 4 cases of low grade sarcoma and 13 cases of high grade malignancy. With 19 cases of distal humerus, 3 cases of proximal ulna and 1 case of elbow. Each patient underwent tumor resection followed by restrictive tumor prosthesis and semi-restrictive of coonrad-morrey prosthesis were used for reconstruction.The duration of the operation, the amount of blood loss, epidemiological data, reconstruction length, oncology parameter, complications and functional evaluation were enrolled and statistical analyzed.Results:The mean length of the osteotomy followed by reconstruction was 12.5±3.9 cm, the mean operative time was 154.1±50.1 minutes, and the mean bleeding was 262.2±100.9 ml. Thirteen patients were treated with customized tumor limited prosthesis while 10 patients with Coonrad-Morrey semi-limited prosthesis. The 5-year survival rates of 23 patients was 64.3%, benign tumors, low-grade and high-grade malignancies were 100%, 100% and 39.7%, respectively. Three cases of lung cancer and three cases of Ewing's sarcoma died during the follow-up period (6/23, 26.1%), one case of giant cell tumor and one case of synovial sarcoma developed local recurrence (2/23, 8.7%). The median range of motion for the elbow increased from 35 to 85 degrees ( t=-13.787, P<0.05), the median NRS score decreased from 5.0 to 0.5 ( t=14.391, P<0.05). Postoperative complications occurred in 9 cases (9/23, 39.1%), the recent complications were nerve injury in 4 cases and infection in 1 case, late complications were prosthesis loosening and failure in 4 cases, the 5 year survival rate of prosthesis was 82.0%. The mean and median MSTS 93 score was 84.5%±11.0% and 88.3% respectively. Conclusion:The local control around the elbow is satisfactory after tumor resection. Total elbow arthroplasty can relieve pain and significantly improve function.