[Individual difference of coronal bowing of femur and its influence on the lower limbs alignment after the total knee arthroplasty].

Objective: To disclose the correlation between the femur bowing angle(FBA) and vulgas correction angle(VCA), anlysys its influence on the total knee arthroplasty and the lower limbs alignment. Methods: From Janurary 2013 to December 2015, 699 patients who had received total knee arthroplasty(TKA)were collected in the Department of Joint Surgery, China-Japan Friendship. The FBA, VCA, offset of the proximal femur, the lengh of the femur, the neck shaft angle of the femur of the eligible cases from the long leg X-ray were measured.All the data were analysed for the following steps: the FBA's mean value and characteristics of distributation of all the cases; the VCA's mean value and characteristics of distributation of all the cases; correlations between the VCA and the other parameters; divide all the cases into four groups based on the value of FBA : group A(FBA<-3°, 29), group B(-3°≤FBA≤0°, 255), group C(0°3°, 236)and then plan to cut the distal femur with 5° and 6°, respectively. The percent of ideal alignmental outcome's percentage of every group were compared. Results: The mean Value of the FBA is -7.1--12.1(1.4±2.4)°; the mean Value of the VCA is 2.5--11.9(6.5±1.3)°. The correlation index between VCA and FBA, the neck shaft angle of the femur , offset of the hip joint, the lengh of the femur is 0.72, -0.26, 0.45 and -0.08, perspectively. The theoretical ideal alignment percentage of the 5 degree-valgus-bone cut and 6 degree-valgus-bone cut in every group is group A: 89.7% and 66.5%; group B: 93.7% and 95.7%; group C: 71.9% and 94.6%; group D: 21.2% and 50.8%, respectively. Conclusion: The cases whose femur bowing angles are outliers are common in daily medical practice, so the vulgas correction angles need be ajusted for its significant correlation with FBA. 5 degree-valgus-bone cut or 6 degree-valgus-bone cut could not get the ideal alignment some times.目的：探讨股骨侧弓角(FBA)对全膝人工关节置换术(TKA)术后下肢力线的影响。方法：收集自2013年1月至2015年12月间中日友好医院骨关节外科就诊的接受TKA术前的病例，按照统一标准，筛选出符合入选标准的病例699例1 000膝，在其标准正位下肢全长X线像测量股骨外翻角(VCA)，FBA，股骨近端偏心距，股骨长度，股骨颈干角，通过对TKA术前患者下肢全长X线像FBA及VCA等数据的测量，进行如下分析：病例中FBA的均数及分布特点；VCA的均数及分布特点；分析VCA与其余参数间彼此的相关性；按照FBA大小将病例分为A组(FBA<－3°，29例)，B组(－3°≤FBA≤0°，255例)，C组(0°3°，236例)4组，模拟分别按照股骨远端5°，6°外翻截骨时，对比各组的理论力线理想率。结果：测量FBA所得均值为－5.7～10.7°(1.4±2.4)°；VCA值为2.5～11.9°(6.5±1.3)°，二者为显著正相关(r＝0.72，P<0.05)；而颈干角，偏心距和股骨长度与股骨VCA的相关系数分别为－0.26，0.45和－0.08；通过理论截骨后股骨力线理想率A组为5°截骨89.7%，6°截骨66.5%；B组为5°截骨93.7%，6°截骨95.7%；C组为5°截骨71.9%，6°截骨94.6%；而D组为5°截骨21.2%，6°截骨50.8%。结论： TKA术前患者中FBA变化范围较大，由于其与VCA的显著正相关性，FBA变化时，TKA术中股骨远端截骨角度应相应调整才能获得满意的术后下肢力线，常规的股骨5°或6°外翻截骨有时难以获得理想的下肢力线。.