Objective: To assess the defatting efficacy of high pressure washing and gradient alcohol and biomechanical properties of defatted bone.Methods: Fresh cancellous bone was obtained from the femoral condyle and divided into six groups according to different defatting treatments, which were: high pressure washing for 10 s (10S group), 20 s (20S group), and 30 s (30S group), gradient alcohol immersion (Alcohol group), acetone immersion (Acetone group), and non-defatted (Fresh group). The appearance of six groups was observed, and the appearance of defatted bone and fresh bone was compared. The residual lipid content and infrared spectrum were used to compare the efficacy of defatting, the DNA content was used to compare the cell content after defatting, and the maximum stress and elastic modulus were used to compare the effects of defatting treatment on biomechanical properties. Results:The fresh bone was yellow and the pores contained a lot of fat. The defatted bone was white and the porous network was clear. There was no difference in residual lipid content among the three groups with high pressure washing (1.45% AE 0.16%, 1.40% AE 0.13%, and 1.46% AE 0.11%, respectively) (P = 0.828). There was no difference in residual lipid content among the 10S, alcohol, and acetone groups (1.45% AE 0.16%, 1.28% AE 0.07%, and 1.13% AE 0.22%, respectively) (P = 0.125). Infrared spectra showed that the fat content of the five defatting groups was significantly lower than that of the fresh group. There was no difference in residual lipid content among the three groups with high pressure washing (4.53 AE 0.23 ug/mL, 4.61 AE 0.18 ug/mL, and 4.66 AE 0.25 ug/mL, respectively) (P = 0.645). There was no difference in residual lipid content among the 10S, alcohol, and acetone groups (4.53 AE 0.23 ug/mL, 4.29 AE 0.24 ug/mL, and 4.27 AE 0.29 ug/mL, respectively) (P = 0.247). The maximum stress of the bone decreased significantly with the increase of the washing time (9.95 AE 0.31 Mpa, 9.07 AE 0.45 Mpa, and 8.17 AE 0.35 Mpa, respectively) (P = 0.003). The elastic modulus of the bone decreased significantly with the increase of the washing time (116.40 AE 3.54 Mpa, 106.10 AE 5.29 Mpa, and 95.63 AE 4.08 Mpa, respectively) (P = 0.003). There was no statistical difference in the maximum stress between the fresh group, the 10S group, the alcohol group, and the acetone group (10.09 AE 0.67 Mpa, 9.95 AE 0.31 Mpa,10.11 AE 0.07 Mpa, and 10.09 AE 0.39 Mpa, respectively) (P = 0.963). There was no statistical difference in the maximum stress between the fresh group, the 10S group, the alcohol group and the acetone group (119.93 AE 4.94 Mpa, 116.40 AE 3.54 Mpa, 118.27 AE 0.85 Mpa, 118.10 AE 4.52 Mpa, respectively) (P = 0.737). Conclusion:The defatting efficiency was satisfactory at a time of 10 s under high pressure washing. In terms of defatting efficiency and its effect on biomechanical properties of bone, high pressure washing and gradient alcohol were similar to conventional acetone solvent extraction defatting.

Background Aseptic loosening of distal femoral tumor implants significantly correlates with the resection length. We designed a new “sleeve” that is specially engaged in the metaphysis at least 5 cm proximal to the knee joint line to preserve as much bone stock as possible. This study investigates the influence of a metaphyseal sleeve on the stress-strain state of a bone tumor implant system in the distal femur. Methods Cortex strains in intact and implanted femurs were predicted with finite element (FE) models. Moreover strains were experimentally measured in a cadaveric femur with and without a sleeve and stem under an axial compressive load of 1000 N. The FE models, which were validated by linear regression, were used to investigate the maximal von Mises stress and the implanted-to-intact (ITI) ratios of strain in the femur with single-legged stance loading under immediate postoperative and osseointegration conditions. Results Good agreement was noted between the experimental measurements and numerical predictions of the femoral strains (coefficient of determination (R2) ≥ 0.95; root-mean-square error (RMSE%) ≈ 10%). The ITI ratios for the metaphysis were between 13 and 28% and between 10 and 21% under the immediate postoperative and osseointegration conditions, respectively, while the ITI ratios for the posterior and lateral cortices around the tip of the stem were 110% and 119% under the immediate-postoperative condition, respectively, and 114% and 101% under the osseointegration condition, respectively. The maximal von Mises stresses for the implanted femur were 113.8 MPa and 43.41 MPa under the immediate postoperative and osseointegration conditions, which were 284% and 47% higher than those in the intact femur (29.6 MPa), respectively. Conclusions This study reveals that a metaphyseal sleeve may cause stress shielding relative to the intact femur, especially in the distal metaphysis. Stress concentrations might mainly occur in the posterior cortex around the tip of the stem. However, stress concentrations may not be accompanied by periprosthetic fracture under the single-legged stance condition.

Objective: To study the effect of concentrated growth factor (CGF) on reducing bone resorption in immediate implant. Methods: 20 immediate implant patients were divided into two groups, each group included 10 patients who were treated by adding CGF or Bio-oss to the gap of implant-bone, respectively; the labial new bone regeneration was evaluated in postoperative 1 years using cone beam CT. Results: The buccal bone width variation of the CGF group was 0.85±0.25mm, and the Bio-oss group was 0.35±0.25mm (p <0.05). Conclusion: The CGF has no significant role in promoting new bone regeneration when was used alone in the gap of implant - bone in immediate implant

Objective：The aim of the study was to explore most effective way to control infection during implant treatment. Methods: The study was carried out in two implant operating surgeries (Surgery A, Surgery B), which were set up air disinfectant machine and ultraviolet disinfection respectively. For baseline measurements, the number of bacterials in the air of the two surgeries was counted at 5min, 15min, 30min, 45min and 60min before sanitizing. To compare sanitizing effect of static air disinfection, air samples from these surgeries were collected for bacterial cultivation after sanitizing for 5min, 15min, 30min, 45min and 60min, and the the sterilization rate was calculated. To compare dynamic air disinfection, the two surgeries were sterilized before implant surgery, and the air samples were collected at 5min, 15min, 30min, 45min, 60min after implant operation. Results: There were no significant differences between air disinfectant machine and ultraviolet disinfection in static air disinfection (p<0.05). However, air disinfectant machine was more effective in dynamic air disinfection. Conclusion：Air disinfectant machine is the most effective way for the prevention of nosocomial infections.

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