全膝关节置换术股骨髓外定位系统的研制及初步临床应用

Primary usage of a new designed extramedullary femoral alignment system in total knee arthroplasty

目的探讨应用自主研发的髓外定位系统进行全膝关节置换术股骨远端定位截骨的可行性及其初步临床应用疗效。方法2015年1至8月采用自主研发的髓外定位器械进行股骨远端截骨全膝关节置换的连续晚期骨关节炎或类风湿关节炎病例20例（髓外定位组），男3例，女17例；年龄52-82岁，平均70．1岁。2015年4至9月采用常规髓内定位进行股骨远端截骨全膝关节置换的晚期骨关节炎或类风湿关节炎病例20例（髓内定位组），男5例，女15例；年龄52-87岁，平均65．9岁。髓外定位组术前行双侧髋关节CT扫描明确股骨头中心与髂前上棘的关系，术中参考双侧髂前上棘定位股骨头中心、以内外上髁连线中点确定膝关节中心，髓外定位器械参考股骨头与膝关节中心连线放置并完成股骨远端截骨。比较两组术中出血量、术后引流量、术后1周内冠状面及矢状面假体力线，术后1周、6周和3个月的屈伸活动度。结果两组患者年龄、术前髋膝踝角（hip-knee—ankle angle，HKA）、美国特种外科医院（Hospital for Special Surgery，HSS）膝关节评分、体重指数、手术时间差异无统计学意义。髓外定位组与髓内定位组术中出血量分别为（121±64）ml和（177±47）ml（P〈0．05），术后引流量分别为（181±149）ml和（292±156）ml（P〈0．05）；术后股骨假体冠状面角分别为89．8°±2．1°和89．8°±2．2°（P〉0．05），股骨假体屈曲角分别为-0．8°±2．2°和2．5°±2．1°（P〈0．05）；术后1周屈伸活动度分别为103．8°±7．8°和102．5°±7．2°（P〉0．05）、术后6周分别为108．5°±8．0°和108．3°±7．4°、3个月分别为117．0°±7．1°和114．5°±8．1°（P〉0．05）。结论自主研发的髓外定位系统具有操作可行性，其矢状面定位精确度较髓内定位更高，术中出血量更小，术后早期膝关节活动度与采用髓内定位者相同。

Objective To investigate the outcome of a new designed extramedullary femoral alignment system and to compare with conventional intramedullary system in clinical results. Methods Twenty consecutive patients （3 males and 17 females with an average age of 70.1 （range, 52-82 years old） with osteoarthritis （OA） or rheumatoid arthritis （RA） who were treated with the extramedullary method between January 2015 to August 2015 and 20 consecutive patients （5 males and 15 females with an average age of 65.9 （range, 52-87 years old） with OA or RA treated with conventional intramedullary method between April 2015 to September 2015 were studied. In extramedullary group, CT scan was used to evaluate the relation between the hip （femoral head） center and anterior superior iliac spine preoperatively. During the total knee arthroplasty, the hip joint center was defined according to the anterior superior iliac spine （ASIS）. Knee joint center was defined as the center of the line connecting medial and lateral epicondyle. The terminal femoral bone cut plane was defined as the line between femoral and knee center. In intramedullary group, the traditional intramedullary method was adopted. The coronal and sagittal alignment, blood loss and drainage at one week postoperatively and the range of motion at one week, 6 weeks and 3 months were evaluated. Results There was no significant difference in age, hip-knee-ankle （HKA） angle, the Hospital for Special Surgery （HSS） Knee Score, BMI, operation time within the two groups. Blood loss and drainage in extramedullary group （121±64 ml and 181±149 ml） was significantly less than that in intramedullary group （177±47 ml and 292±156 ml）. There was no significant difference in coronal alignment of the femoral prosthesis within the two groups （89.8°±2.1° v.s. 89.8°±2.2°, P〉0.05）. However, the two groups had significant difference in sagittal alignment （-0.8°±2.2° v.s. 2.5°±2.1°, P〈0.05）. The alignment of extramedullary group had much more tendency in flexion degree. No difference was found in range of motion at 1 week, 6 weeks and 3 months postoperatively （103.8°±7.8° v.s. 102.5°±7.2°, 108.5°±8.0° v.s. 108.3°±7.4° , 117.0°±7.1° v.s. 114.5°±8.1°, P〉0.05）. Conclusion The present designed extramedullary system is practical in total knee arthroplasty and has more accuracy in sagittal plane. The patients treated with extramedullary system have less blood loss and drainage and have similar range of motion in early stage after operation when compared with the intramedullary method.