Objective:Objective The potential of a three- dimensional bioprinted cell-laden gelatin methactyloyl (GelMA)+ hyaluronic acid (HA) composite bioink in tissue engineering was assessed by evaluating cell viability, scaffold morphology, and cell compatibility.Methods:Rabbit chondrocytes were isolated and cultured. Composite hydrogels were prepared using GelMA and HA, and their applicability in tissue engineering was assessed by evaluating physicochemical properties, cytocompatibility, and printability. The swelling and mechanical properties of 100g/L GelMA inks as the control group, and 100g/L GelMA+ 20g/L HA inks as the experimental group were assessed following photocrosslinking of the cylindrical model. The printing resolution of the GelMA/HA mesh scaffold loaded with chondrocytes was evaluated based on appearance and expansion ratio. Cell viability was determined using cell live/dead test after 14 days, while cytocompatibility was observed through in vitro microscopy and multiple immunofluorescence staining after 7 days. GraphPad Prism 8.0 was utilized for data visualization and statistical analysis. Independent-samples t-test was employed to compare differences among groups. A P-value less than 0.05 was considered statistically significant. Results:The swelling ratio of GelMA group was 10.57±0.40, which exceeded that of the GelMA+ HA group (7.63±0.61, P<0.05). The compressive elastic modulus of GelMA+ HA group measured (77.53±4.30) kPa, significantly surpassing that of the GelMA group [(25.60±5.70) kPa, P<0.05]. The extension ratio of GelMA was 2.59±0.33, while the experimental group recorded 2.66±0.12, with no statistically significant difference between them ( P>0.05). There were no notable disparities in cell viability between the two groups; both exhibited viabilities greater than 85%. On the initial day of culture, both groups exhibited intact structures, regular pores, and a substantial number of spherical cells. After 14 days of culture, the GelMA scaffold structure appeared blurred with nearly vanished pores, while large live cells were visible. The GelMA+ HA scaffold structure was slightly more relaxed with relatively intact pores and a significant presence of live cells. Furthermore, multiple immunofluorescence staining after 7 days of culture revealed no notable disparity in cell count and collagen components between the two groups; however, cell morphology in the GelMA+ HA group displayed significant elongation and clustering. Conclusion:The GelMA+ HA hydrogel exhibits enhanced mechanical properties and reduced swelling ratio, rendering it suitable for the fabrication of complex structures. Additionally, it demonstrates excellent cell compatibility.

Objective:Objective The potential of a three- dimensional bioprinted cell-laden gelatin methactyloyl (GelMA)+ hyaluronic acid (HA) composite bioink in tissue engineering was assessed by evaluating cell viability, scaffold morphology, and cell compatibility.Methods:Rabbit chondrocytes were isolated and cultured. Composite hydrogels were prepared using GelMA and HA, and their applicability in tissue engineering was assessed by evaluating physicochemical properties, cytocompatibility, and printability. The swelling and mechanical properties of 100g/L GelMA inks as the control group, and 100g/L GelMA+ 20g/L HA inks as the experimental group were assessed following photocrosslinking of the cylindrical model. The printing resolution of the GelMA/HA mesh scaffold loaded with chondrocytes was evaluated based on appearance and expansion ratio. Cell viability was determined using cell live/dead test after 14 days, while cytocompatibility was observed through in vitro microscopy and multiple immunofluorescence staining after 7 days. GraphPad Prism 8.0 was utilized for data visualization and statistical analysis. Independent-samples t-test was employed to compare differences among groups. A P-value less than 0.05 was considered statistically significant. Results:The swelling ratio of GelMA group was 10.57±0.40, which exceeded that of the GelMA+ HA group (7.63±0.61, P<0.05). The compressive elastic modulus of GelMA+ HA group measured (77.53±4.30) kPa, significantly surpassing that of the GelMA group [(25.60±5.70) kPa, P<0.05]. The extension ratio of GelMA was 2.59±0.33, while the experimental group recorded 2.66±0.12, with no statistically significant difference between them ( P>0.05). There were no notable disparities in cell viability between the two groups; both exhibited viabilities greater than 85%. On the initial day of culture, both groups exhibited intact structures, regular pores, and a substantial number of spherical cells. After 14 days of culture, the GelMA scaffold structure appeared blurred with nearly vanished pores, while large live cells were visible. The GelMA+ HA scaffold structure was slightly more relaxed with relatively intact pores and a significant presence of live cells. Furthermore, multiple immunofluorescence staining after 7 days of culture revealed no notable disparity in cell count and collagen components between the two groups; however, cell morphology in the GelMA+ HA group displayed significant elongation and clustering. Conclusion:The GelMA+ HA hydrogel exhibits enhanced mechanical properties and reduced swelling ratio, rendering it suitable for the fabrication of complex structures. Additionally, it demonstrates excellent cell compatibility.

Objective:To introduce our experience in the treatment of infection related to lower long bone fracture in adults.Methods:From January 2017 to December 2020, 31 adult patients with infection related to lower long bone fracture were treated at Department of Orthopaedics, the 7th Medical Center, General Hospital of the People's Liberation Army. They were 20 males and 11 females with an age of (35.7±16.7) years. There were 9 cases of acute infection, 3 cases of delayed infection and 19 cases of late infection. They were treated according to their stage of infection, respectively, by retaining or removing the internal fixation, debridement, bone grafting and bone lengthening. They were followed up regularly for at least 12 months to observe their symptoms, signs, indexes of imaging and blood tests. Paley score for fracture union was recorded at the last follow-up.Results:All the 31 patients were followed up for 13.0(13.0, 31.0) months. Of the 9 patients with acute infection, 6 retained the implant, 1 removed the implant for dressing change due to intolerability and 2 removed the implant due to unsatisfactory infection control. Of the 3 patients with delayed infection, 1 retained the implant and 2 removed the implant because of unsatisfactory infection control. Of the 19 patients with delayed infection, 5 were treated with local bone graft, 6 with Masqulet technique and 8 with bone transfer following debridement and implant removal. All patients were cured without recurrence of infection. According to Paley's scoring, 25 cases were excellent, 5 were good, and 1 was fair.Conclusions:Treatment of infection related to lower long bone fracture in adults should be carried out according to its clinical stage. For acute and delayed infection, implants should be preserved as much as possible; for chronic infection, implants should be removed to perform bone and soft tissue reconstruction after thorough debridement. Personalized diagnosis and treatment protocols can lead to satisfactory clinical results.

Objective:To study the risk factors of acute stroke within 1 year after hip fracture in the elderly and its effect on prognosis.Methods:From January 2018 to December 2020, 278 elderly hip fracture patients undergoing surgery were retrospectively analyzed, including 101 males and 177 females, aged from 60 to 99 years with an average of(78.9±8.7)years.According to whether acute stroke occurred within 1 year after operation, the patients were divided into stroke group and non-stroke group.A multivariate Logistic regression was used to evaluate the risk factors for acute stroke within 1 year after hip fracture, and the prognosis was analyzed.Results:Acute stroke occurred in 28 patients(10.1%)within 1 year after operation, and the peak of stroke onset occurred in the third months after operation.Patients in the stroke group were older, and had a higher proportion of hypertension, arrhythmia, previous stroke history, and use of anticoagulant or antiplatelet drugs before fracture( P<0.05 for all). Multivariate Logistic regression analysis showed that advanced age( OR=1.078, 95% CI=1.007-1.153, P=0.030), male( OR=2.643, 95% CI=1.060-6.742, P=0.037)and previous stroke history( OR=12.202, 95% CI=4.662-31.940, P<0.001)were independent risk factors for stroke in elderly patients with hip fracture within 1 year after operation.The 1-year mortality, complication rate and readmission rate in the stroke group were significantly higher than those in the non-stroke group( P<0.05 for all). Conclusions:The incidence of stroke is high in elderly patients with hip fracture within 1 year after operation.Older age, male, and previous stroke history were independent risk factors for acute stroke.The prognosis of stroke was poor in elderly patients with hip fracture, and the 1-year mortality, complication and readmission rates were high.