Objective:To summarize the technical points of microwave ablation for inactivating the preserved bone in situ combined with hip prosthesis for proximal femoral malignancy and analyze its clinical efficacy.Methods:A total of 28 patients with proximal femoral malignancy who were treated in Tianjin Hospital from January 2018 to December 2021 were included in the study. There were 12 males and 16 females, aged 65.3±10.9 years (range 39-85 years); 26 metastatic bone tumors and 2 patients with proximal femoral primary tumors accompanying marrow cavity jumping focus in the study. According to whether the tumor bone mass was preserved in situ during microwave ablation, the patients were divided into the bone mass preservation group (18 cases) and conventional surgery group (10 cases). In the bone mass preservation group, according to the evaluation of preoperative CT and MRI, part of the tumor bone was preserved in situ and hip arthroplasty was performed after microwave inactivation. In the conventional surgery group, total resection of the tumor and microwave inactivation were performed firstly, and then hip prosthesis replacement was performed. Clinical efficacy was evaluated by comparing the length of osteotomy, the postoperative prosthesis stability and Musculoskeletal Tumor Society (MSTS) score.Results:The follow-up time of 28 patients was 11.9±5.9 months (range 4 to 24 months). The intraoperative length of osteotomy was 9.2±2.5 cm in the bone mass preservation group and the intraoperative length of osteotomy was 15.4±3.6 cm in the conventional surgery group, and the difference between the two groups was statistically significant ( t=5.40, P=0.002). There were 5 common hip prosthesises and 13 modular hip prosthesises in the bone mass preservation group. In 2 patients with common prosthesis, X-ray showed partial bone resorption at the osteotomy interface 3 and 8 months after operation, no loosening or fracture at the prosthesis-bone interface, and no pain or limitation of walking. There were 10 modular hip prosthesises in the conventional surgery group, with one patient suffered pain while walking at 19 months after surgery, and the X-ray suggested loosening between the prosthesis-bone interface. MSTS score of bone mass preservation group at 3 months post-operation was 16.6±1.9 points, including good 6 cases and moderate 12 case, and the excellent and good rate was 33%, meanwhile MSTS score of conventional surgery group was 15.5±3.6 points, including good 3 cases, moderate 5 cases and poor 2 cases, and the excellent and good rate was 30% at 3 months post-operation, and the difference between the two groups was not statistically significant ( t=0.94, P=0.366). MSTS score of bone mass preservation group at 6 months post-operation was 21.7±3.2 points, including excellent 3 cases, good 9 cases, moderate 1 case and poor 1 case, and the excellent and good rate was 86% (12/14), meanwhile MSTS score of conventional surgery group at 6 months post-operation was 16.5±4.9 points, including excellent 1 case, good 3 cases, moderate 3 cases and poor 2 cases, and the excellent and good rate was 44% at 6 months post-operation, and the difference between the two groups was statistically significant ( t=3.03, P=0.006). MSTS score of bone mass preservation group at 12 months post-operation was 22.3±7.6 points, including excellent 8 cases, good 2 cases, moderate 1 case and poor 1 case, and the excellent and good rate was 83% (10/12), meanwhile conventional surgery group at 12 months post-operation was 22.1±6.6 points, including excellent 3 case, good 3 cases, moderate 1 cases and poor 1 cases, and the excellent and good rate was 75%(6/8), and the difference was not statistically significant ( t=0.06, P=0.957). The MSTS scores of 6 months after operation, including movement function, acceptance degree, brace assistance and walking ability, were significantly improved in the bone mass preservation group compared with the conventional surgery group, and the differences were statistically significant ( t=2.33, P=0.030; t=2.74, P=0.012; t=2.80, P=0.011; t=2.59, P=0.026). Conclusion:Preserved bone mass in situ inactivated by microwave ablation combined with tumor hip prosthesis is an alternative surgical method for the treatment of proximal femoral malignancy, which can increase the stability of the prosthesis, facilitate the biological reconstruction of soft tissues and early functional recovery.

背景:动物实验表明在骨不连断端的纤维组织中仍存在一定数量的成骨细胞及成骨因子,并且断端周围血管数量与正常骨折愈合组织差异无统计学意义.目的:观察机械应力作用下骨不连断端成骨生长因子骨形态发生蛋白、血管内皮生长因子、转化生长因子β1的变化.方法:选取60只成年雄性SD大鼠,通过股骨干截骨,采用自制可调节加压式外固定架建立骨不连模型.术后第4,8,12周X射线片及组织学观察断端变化,确立骨不连模型,排除感染、外架脱落等个体.选取40只骨不连模型大鼠随机分成2组:实验组定期给予低强度高频率应力刺激;对照组无应力刺激.3个月后采用放射学评分和组织学切片观察骨不连断端成骨情况;通过RT-PCR及免疫组化评估不同时间段断端组织中骨形态发生蛋白2、血管内皮生长因子及转化生长因子β1的表达及差异.结果与结论:①第12周X射线片及组织学显示断端髓腔骨性封闭,无骨桥连结,结缔纤维组织填充,骨不连模型建立;②实验组第4周,断端间隙显影模糊;第8周断端间隙呈絮状影;第12周断端间隙出现单侧的骨桥,第12周X射线评分显著高于第4,8周及对照组(P<0.05);③RT-PCR及免疫组化结果显示,实验组骨形态发生蛋白2表达在第8周达到峰值,血管内皮生长因子基因扩增在第4周出现高峰,而其表达在第8周出现峰值,转化生长因子β1表达趋势平稳;实验组不同时间段成骨因子表达均显著高于对照组(P<0.05);④结果表明,机械应力作用下骨不连断端骨形态发生蛋白2、转化生长因子β1、血管内皮生长因子表达增高,断端间有新骨形成,提示低强度应力有促进成骨的作用.