计算机辅助膝内翻及外翻畸形分析和精确矫形

目的探讨计算机辅助膝关节内外翻畸形分析和精确矫形的新方法，评价计算机辅助技术在膝内外翻畸形治疗中的价值。方法2005年9月～2010年9月共收治膝内、外翻畸形患者18例；膝内翻4例，膝外翻14例。其中男6例，女12例；年龄14～54岁，平均25．4岁。所有患者采用薄层CT扫描获取双下肢的二维图像数据，计算机辅助建立的双下肢三维解剖模型，将双下肢三维解剖模型导入逆向工程软件Imageware中，通过计算机辅助精确测量股骨角、胫股角、胫骨关节面夹角等参数，根据计算机辅助测量结果，选择合适的截骨部位、截骨角度，通过提取表面点云数据，CAD设计个性化辅助截骨模板，最后采用计算机模拟设计膝关节内外翻畸形的精确截骨和矫形的手术过程。术中根据计算机辅助模拟的手术方案，对4例膝关节内翻畸形患者采用胫骨近端截骨＋内固定术，14例膝关节外翻畸形患者采用股骨髁上截骨＋内固定术。采用膝关节HSS评分标准评定术前、术后的膝关节功能。结果所有患者均得到随访，随访时间9～36个月，平均18．7个月。术后早期X线证实：膝内、外翻畸形完全矫正，下肢负重力线恢复正常。术前计算机辅助测量与X线的测量值，两者测量无统计学差异（P〉0．05）；术前及术后X线测量的股骨角、胫股角、胫骨关节面夹角等参数对比，具有统计学差异（P〈0．05）。根据膝关节HSS评分标准：术前（55．4±15．2）分，术后半年（81．8±9．6）分，两者差异有统计学意义（P〈0．05）。传统方法组与计算机辅助矫形组相比，术后口角、B角和膝关节功能评分具有统计学差异（P〈0．05）。随访期间未发现有内固定失败、骨不愈合、膝内外翻复发、无神经血管损伤等并发症；其中3例患者术后2周出现异体骨排斥反应，给予伤口换药治疗后好转，随访期间未发现骨不愈合。结论采用计算机辅助膝内外翻分析和精确矫形，将膝内外翻畸形的精确矫形提升到数字化水平，具有更加精确、更加可靠、更加良好的治疗效果。

Precisely analysis and reconstruction of genu varum and valgum using computer-aided design

Objective To investigate a new way of precise analysis and reconstruction of genua varus and valgum using computer aided design technology, and to evaluate the curative effects. Methods 18 cases of genua varus or genua valgum were treated from September 2005 to September 2010, among which four cases were genua varus, and 14 cases were genua valgum. There were six males and 12 females, aging from 14 to 54 years （average 25.4 years）. All patients were examined by lamellar CT scan to harvest two dimensional image of lower limbs. Three dimensional reconstruction of anatomical models was performed by Mimics 10. 0 software in computer. 3D models were imported into reverse engineering sofeware Imageware to measure the angles of varus or valgum, femoral angle, femoral condyle-tibial plateau angle, and femorotibial angle. The position and extent of osteotomy can be precisely determined according to the results of computer aided measurement. The surface points cloud data were collected to design individual osteotomy-assisting templates by computer-aided design （CAD） software, and the virtual procedure of the osteotomy and reconstruction of genua varus and valgum were simulated in the reverse engineering software. Four cases of genua varus were performed with high tibial osteotomy ＋ internal fixation, and 14 cases of genua valgum were performed with distal femoral ＋ internal fixation. The hospital for special surgery knee score （HSS） was used to evaluate the preoperative and postoperative functions of the knee joint. Results All patients were followed up for 9 - 36 months （ average 18.7 months） ; the fracture union time was 8 - 12 months （average 10. 5 months）. The load bearing line of lower limb had been completely recovered according to postoperation X-Ray image. The parameter of computer aided measurement had no significant difference （ P 〉 0. 05 ） comparing with X-ray measurement. According to X-ray measurement, the angles of genua varus or valgum, femoral angle, femoral condyle-tibial plateau angle, and femorotibial angle had significant difference （P 〈 0. 05 ） comparing preoperative data to postoperative data. The α and β angle and HSS score of traditional method were significant different compared to those of computer aided design method （ P 〈 0. 05 ）. The average HSS score had increased from （55.4 ± 15.2） in preopertion to （81.8 ±9. 6） in postoperation, and there was significant difference （P 〈 0. 05）. According to the HSS score at the last follow-up, seven cases were excellent, and four cases were good. No internal fixation device failure, bone nounion, genua varus and valgum recurrence occurred in the follow-up. There was reject reaction of allograft bone in three cases, and it turned out well ＇after symptomatic treatment. Conclusions Precise analysis and reconstruction of genua varus and valgum using computer-aided design will lead orthopedics into an age of digitalization, and provide a much more precise, reliable and better curative effect.