应用3D打印假体重建下肢肿瘤性长节段骨缺损

Aplication of 3D-printed prosthesis on construction of long segmental bone defect after tumor resection

目的探讨钛合金3D打印假体复合带血管蒂腓骨及生物陶瓷重建下肢瘤段切除后长节段骨缺损的可行性。方法2015年8月至2016年11月采用瘤段切除后长节段管状钛合金3D打印假体重建5例，男1例，女4例；年龄16～56岁，平均（32～19.3）岁。肿瘤病理类型：高分化软骨肉瘤1例，尤文肉瘤1例，单发转移瘤1例，骨肉瘤2例。基于患者术前CT扫描、MRI以及骨扫描的影像学资料，使用Materialise Mimics 17．0加载dicom格式的数据，设计假体、导板及手术方案，并经过计算机辅助有限元力学验证假体强度。假体通过钛合金3D打印方法加工后，按设计方案完成骨缺损重建，假体内部复合带血管腓骨及生物陶瓷。结果2例采用选择性激光熔化技术、3例采用电子束熔融技术3D打印加工假体；假体均做多孔化减重处理，长度（210．98±66．16）mm，容积（26901．76±12903．96）mm^3。均按计划实施手术，远、近端髓腔内组织术中冰冻病理均未见明确肿瘤组织。术中假体安装牢固，4例进行腓骨瓣及多孔磷酸三钙颗粒复合植入，腓骨瓣长度为（168．75±49．07）mm，均未折叠，多孔磷酸三钙颗粒植入量为（10±4．08）g；1例转移瘤的假体内使用骨水泥填充。平均手术时间为（261±85）min，平均出血量为（540±182）ml。随访时间1-15个月，平均6．4个月。5例均存活，肿瘤未见局部复发及肺转移，世界骨与软组织肿瘤协会（The Musculoskeletal Tumor Society，MSTS）93评分为17-26分，2例带血管蒂腓骨移植者术后3个月骨扫描证实腓骨血运良好。1例股骨假体近端固定钉孔的第2枚螺钉发生断裂，未影响稳定性。结论应用钛合金3D打印假体复合带血管蒂腓骨及生物陶瓷的方式可以应用于长节段骨缺损的修复，短期随访结果证实这种复合重建方式修复下肢瘤段切除后的长节段骨缺损稳定性可靠，安全性高，可获得良好的下肢功能。

Objective To explore the feasibility and clinical efficacy of long-segmental bone defects after en bloc tumor resection of lower limb segment with composite of titanium alloy 3D printed prosthesis and vaseularized fibular autograft and bieceramics. Methods 5 patients with lower extremity tumor （1 high grade chondrosarcoma, 1 Ewing sarcoma, 1 single metastatic tumor and 2 osteosarcoma） were treated by en bloc resection and precise reconstruction with segmental 3D-printed, custom-made prosthesis from August 2015 to November 2016, which composed of 1 male and 4 females, ranged from 16 to 56 years old, the average was 32±19.3 years old. Three-dimensional computed tomography reconstructed images of patients＇ tumors were built before surgery. Custom-made prostheses were manufactured based on the patients＇ reconstructed images with micro-pores on the surface. After en bloc tumor resection with the help of osteotomy guide plate, the defects were reconstructed with 3D-printed, custom-made prostheses. Vascularized fibular autografts were put inside the prostheses, and the interval space among them was filled with bioceramics. Results All the 5 cases were performed surgical planning before the surgery with prosthesis and guide plate were designed at the same time. After verification of the finite element analysis SLM （2 cases） and the EBM （3 cases） were used to process prosthesis, and were designed into porous sharp with 210.98＋66.16 mm in length and 26 901.76±12 903.96 mm^3 in volume. Then the prosthesis would be cleaned and sterilized. All 5 operation were proceeded according to the plan of preoperative. The intra-operative guide plate were installed on the bone surface stably. The bone cutting was guided according to the plan of preoperative. By intra-operative frozen pathological examination, there were no malignant tissues in near and far marrow cavity. Unfolded fibular flap with 168.75±49.07 mm in length and porous tricalcium phosphate particle composite implants with 10±4.08 g were used in 4 cases and bone cement was used in 1 cases of metastatic tumor. The average operation time was 261±85 min and average blood loss was 540±182 ml. After a mean follow-up time of 6.4 months （1-15 months）, all 5 cases survived with no local recurrence and pulmonary metastasis tumor. 2 cases with vascular pedicle fibular transplant confirmed the survival of fibula via bone scan 3 months after operation. All cases were no infection, fractures, prosthesis loosening, except broken screw in 1 case. The Musculoskeletal Tumor Society （MSTS） 93 score was 17-26. Conclusion Long segment tubular titanium alloy 3D printed prosthesis with vascularized fibular autograft and bioceramics could reconstruct the segmental defects caused by tumor resection.