钉棒假体半骨盆Ⅰ+Ⅱ+Ⅲ区重建的生物力学分析及疗效评价

Biomechanical analysis and effectiveness evaluation of zone Ⅰ+Ⅱ+Ⅲ reconstruction of hemipelvis with rod-screw prosthesis

目的 在构建包含肌肉韧带的骨盆三维有限元模型基础上,分析钉棒假体生物力学性能,并结合临床应用评价钉棒假体半骨盆Ⅰ+Ⅱ+Ⅲ区重建的疗效。方法 以2015年1月—2020年12月21例行半骨盆恶性肿瘤(Ⅰ+Ⅱ+Ⅲ区)切除、钉棒假体重建患者作为研究对象。其中,男11例,女10例;年龄16-64岁,平均39.2岁。肿瘤类型:软骨肉瘤9例,骨肉瘤7例,尤文肉瘤3例,未分化多形性肉瘤2例;根据国际肌肉骨骼肿瘤学会(MSTS)分期:ⅡB期19例,Ⅲ期2例。术前髋关节Harris评分(HHS)和MSTS评分分别为(54.4±3.1)、(14.1±2.0)分。术中15例病灶行广泛性切除,5例边缘性切除,1例病灶内切除。取1例患者术后CT图像,采用Mimics23Suite和3-matic软件建立患者骨盆三维实体模型,同时采用镜像操作获取正常骨盆三维实体模型。继而将两实体模型导入有限元分析软件Workbench2020R1建立三维有限元模型,分别于肌肉构建前后分析双脚站立位的生物力学性能。记录手术时间、术中出血量、手术相关并发症发生情况,以HHS评分和MSTS评分行术后功能评估,同时影像学复查局部复发及转移情况。结果 有限元分析显示重建骨盆应力峰值表现在固定骶骨的S1、2钉棒连接处;肌肉构建前应力峰值高于构建后,但远低于钛合金屈服强度。手术时间为250-370 min,平均297 min;术中出血量3 200-5 500 mL,平均4 009 mL。患者均获随访,随访时间8-72个月,平均42个月。7例存在肺部转移,其中2例为术前转移;5例死亡,其余16例存活,5年生存率为72.1%。术后局部复发3例,均为术中未达到广泛性切除者。术后患者患肢功能均明显改善,恢复行走功能;末次随访时HHS、MSTS评分分别为(75.2±3.0)、(20.4±2.0)分,与术前比较差异有统计学意义(t=22.205,P<0.001;t=11.915,P<0.001)。术后发生切口愈合延迟2例、深部感染2例、螺钉松动1例、假体脱位1例,无假体或螺钉断裂等其他并发症发生。结论 采用钉棒假体半骨盆Ⅰ+Ⅱ+Ⅲ区重建,其强度能够满足患者日常站立要求,是一种可行有效的骨盆重建方式。

Objective To analyze the biomechanical properties of the rod-screw prosthesis based on a pelvic three-dimensional finite element model including muscle and ligament, and evaluate the effectiveness of zoneⅠ+Ⅱ+Ⅲreconstruction of hemipelvis with rod-screw prosthesis in combination with clinical applications. Methods A total of 21patients who underwent hemipelvic tumor resection(zoneⅠ+Ⅱ+Ⅲ) and rod-screw prosthesis reconstruction between January 2015 and December 2020 were selected as the research subjects. Among them, there were 11 males and 10 females;the age ranged from 16 to 64 years, with an average age of 39.2 years. There were 9 cases of chondrosarcoma, 7 cases of osteosarcoma, 3 cases of Ewing sarcoma, and 2 cases of undifferentiated pleomorphic sarcoma. According to the Musculoskeletal Tumor Society Score(MSTS) staging, there were 19 cases of stage ⅡB and 2 cases of stage Ⅲ.Preoperative Harris Hip Score(HHS) and MSTS score were 54.4±3.1 and 14.1±2.0, respectively. Intraoperative 15 cases underwent extensive resection, 5 cases underwent marginal resection, and 1 case underwent intralesional resection.The CT image of 1 patient after reconstruction was used to establish a three-dimensional solid model of the pelvis via Mimics23Suite and 3-matic softwares. At the same time, a mirror operation was used to obtain a normal pelvis model,then the two solid models were imported into the finite element analysis software Workbench 2020R1 to establish threedimensional finite element models, and the biomechanical properties of the standing position were analyzed. The operation time, intraoperative blood loss, and operation-related complications were recorded, and the postoperative evaluation was carried out with HHS and MSTS scores. Finally, the local recurrence and metastasis were reviewed.Results Finite element analysis showed that the peak stress of the reconstructed pelvis appeared at the fixed S1, 2 rodscrew connections;the peak stress without muscles was higher than that after muscle construction, but much smaller than the yield strength of titanium alloy. The operation time was 250-370 minutes, with an average of 297 minutes;the amount of intraoperative blood loss was 3 200-5 500 mL, with an average of 4 009 mL. All patients were followed up 8-72 months,with an average of 42 months. There were 7 cases of pulmonary metastasis, of which 2 cases were preoperative metastasis;5 cases died, 16 cases survived, and the 5-year survival rate was 72.1%. There were 3 cases of local recurrence, all of whom did not achieve extensive resection during operation. The function of the affected limbs significantly improved, and the walking function was restored. The HHS and MSTS scores were 75.2±3.0 and 20.4±2.0 at last follow-up, respectively, and the differences were significant when compared with those before operation(t=22.205, P<0.001;t=11.915, P<0.001).During follow-up, 2 cases of delayed incision healing, 2 cases of deep infection, 1 case of screw loosening, and 1 case of prosthesis dislocation occurred, and no other complication such as prosthesis or screw fracture occurred.Conclusion The stress and deformation distribution of the reconstructed pelvis are basically the same as normal pelvis.The rod-screw prosthesis is an effective reconstruction method for pelvic malignant tumors.