3D打印技术辅助创伤性膝内翻畸形矫正的初步临床应用

Application of 3D printing in treatment of traumatic knee varus deformity： a pilot study

目的探讨3D打印技术辅助创伤性膝内翻畸形矫正的临床应用效果。方法对2010年9月至2013年4月收治的27例创伤性膝内翻畸形患者（男15例，女12例；平均年龄为37．8岁；左侧10例，右侧17例；畸形角度平均为20．1°）行下肢连续螺旋CT扫描，将原始Dicom格式数据导入Mimics10．01软件，三维重建双下肢骨骼模型，以STL格式保存，导入3-matic6．1软件，测量下肢内翻角度、胫股角（FTA）、膝关节内侧间隙距离，寻找胫骨最佳截骨角度，设计与截骨部位解剖形态一致的截骨模板，借助3D打印技术制作出实物模板，术中通过模板确定最佳截骨方位进行截骨，最后行钢板及螺钉内固定。术前、术后3个月及术后1年行双下肢全长X线片检查，测量双下肢FTA和膝关节内侧间隙；采用美国特种外科医院（HSS）膝关节评分标准评定膝关节功能。结果27例患者术后获7～36个月（平均23．4个月）随访。所有患者均获骨性愈合，愈合时间为3—5个月，平均3．3个月。27例患者术后3个月及术后1年的FTA、膝关节内侧间隙距离均大于术前，术后1年的HSS膝关节评分高于术前和术后3个月，术后3个月的HSS膝关节评分又高于术前，差异均有统计学意义（P〈0．05）。末次随访时根据HSS膝关节评分标准评定疗效：优21例，良4例，可2例，优良率为92．6％。结论将3D打印技术和计算机辅助设计相结合设计个体化截骨模板，可大大提高截骨的精确性，获得更好的下肢力线，为治疗创伤性膝内翻畸形提供了一种简单、有效的方法。

Objective To explore the clinical effect of using 3D printing in the treatment of genua varus deformity. Methods From September 2010 to April 2013, 27 cases of genua varus were admitted. They were 15 men and 12 women, with an average age of 37.8 years. The deformity affected the left side in 10 cases and the right in 17, with an average angle of 20. 1°. All patients were examined by lamellar CT scan to harvest the original data of lower limbs. Three dimensional reconstruction of bone models was performed by software Materialise Mimics 10. 01. 3D models were imported into software 3-matic 6. 1 to measure the angles of varus, femorotibial angle, and the medial interspace of knee joint. The position and angle of osteotomy were precisely determined according to the results of computer-aided measurement. The cloud data of surface points were collected to design individual osteotomy-assisting templates by software Geomagic Studio 11.0, and the virtual procedures of the osteotomy and reconstruction of genua varus were simulated in software Magics 9.55. Physical templates were manufactured using 3D printing technology. In the actual operation, the best location of tibial osteotomy was determined according to the template. After osteotomy, internal fixation was performed using a steel plate and screws. X-ray examinations of bilateral lower limbs were conducted preoperation, 3 and 12 months postoperation. The femorotibial angles and the medial interspaces of knee joint were measured on postoperative X-ray films of lower limbs. The Hospital for Special Surgery （HSS） knee score was used to evaluate the preoperative and postoperative functions of the knee joint. Results All 27 patients were followed up from 7 to 36 months （average, 23.4 months）. The bony union time was 3 to 5 months （average, 3.3 months）. The femorotibial angles and the medial interspaces of knee joint at 3 and 12 months postoperation were significantly greater than those at preoperation, the average HSS score at 12 months postoperation was significantly higher than that at preoperation and 3 months postoperation, and the average HSS score at 3 months postoperation was significantly higher than that at preoperation （ P 〈 0. 05） . According to the HSS scores at the last follow-up, 21 cases were excellent, 4 cases good, and 2 cases fair, giving an excellent to good rate of 92. 6%. Conclusion 3D printing technology can be used along with computer-aided design to manufacture an individualized osteotomy-assisting template which greatly improves the accuracy of bone cutting and ensures better lines of force at the lower limb in the treatment of traumatic knee varus deformity.