Objective:To investigate the effects of different impl an t diameter on stress distribution in implant bone interface. Method: The stress and strain in implant bone interface for implants with di fferent diameter (3.0 mm,3.75 mm and 5.0 mm), and with 1.47 N loading mesiodist ally were analyzed by 3 dimesion finite element analysis method. Re sults:The Von mises stress (MPa)at cervix of the implants with the diameter (mm) of 3.0, 3.75 and 5.0 were 0.807,0.533 and 1.080;the alveolar bone displacement (?m) at the cervix of the implants 0.232,0.163 and,0.111 respe ctively. Conclusion: The implant with 3.75 mm diameter is more suitable for orthodontic anchorage.

Objective:To investigate the clinical effects of tibial transverse bone transport assisted by nose ring drainage (NRD) in the treatment of foot and ankle chronic osteomyelitis.Methods:A retrospective study was conducted to analyze the data of 32 patients with foot and ankle chronic osteomyelitis who had been treated at Department of Orthopedics, Beijing Rehabilitation Hospital from March 2013 to February 2022. The patients were assigned into a study group and a control group. In the control group, there were 12 males and 3 females, aged (39.5±8.8) years. The osteomyelitis was located at the distal tibia in 4 cases, at the talus in 1 case, at the calcaneus in 2 cases, at the midfoot in 4 cases and at the forefoot in 4 cases. According to the Crerny-Mader classification, there were 5 cases of type Ⅰ and 10 cases of type Ⅱ. The control group was treated with Ilizarov transverse tibial bone transport in combination with thorough debridement and anti-infection therapy. In the study group, there were 12 males and 5 females, aged (42.3±13.4) years. The osteomyelitis was located at the distal tibia in 4 cases, at the talus in 1 case, at the calcaneus in 3 cases, at the midfoot in 5 cases and at the forefoot in 4 cases. According to the Crerny-Mader classification, there were 7 cases of type Ⅰ and 10 cases of type Ⅱ. The study group was treated with NRD drainage in addition to the procedures in the control group. The curative effects were evaluated by comparing the cure, recurrence, amputation (toe amputation), antibiotic use time, wound healing time, relevant inflammatory indicators [WBC, neutrophil percentage (NEU), erythrocyte sedimentation rate (ESR), procalcitonin, interleukin-6 (IL-6), C-reactive protein (CRP)], and postoperative functional recovery between the 2 groups.Results:The 2 groups were comparable because there was no statistically significant difference in the general data between them ( P>0.05). The follow-up period was (36.0±9.8) months. There was no significant difference between the 2 groups in the cure or amputation (toe amputation) ( P>0.05), but the recurrence rate in the study group was significantly lower than that in the control group ( P<0.05). The antibiotic use time [(20.7±3.6) d] and wound healing time [(88.3±17.1) d] in the study group were significantly shorter than those [(37.9±6.5) d and (102.2±22.6) d] in the control group ( P<0.05). The ESR, IL-6 and CRP at 1 week after operation in the study group were significantly lower than those in the control group ( P<0.05), but there was no significant difference between the 2 groups in the WBC, NEU or PCT at 1 week after operation ( P>0.05). There was no significant difference either in the inflammatory indicators between the 2 groups at 1 month after operation ( P>0.05). In all patients, the inflammatory indicators like WBC, NEU, ESR, PCT, IL-6 and CRP at 1 week and 1 month after operation were significantly better than those before operation, and the Maryland foot functional score at 12 months after operation was significantly higher than the preoperative one ( P<0.05). There was no significant difference between the 2 groups in the Maryland foot functional score at 12 months after operation ( P>0.05). Conclusion:In the treatment of foot and ankle chronic osteomyelitis, compared with the Ilizarov transverse tibial bone transport, our tibial transverse bone transport assisted by NRD can achieve satisfactory therapeutic effects, shorten antibiotic use time and treatment cycle, and reduce recurrence rate.