外翻膝全膝关节置换术后残留畸形分布及危险因素分析

Distribution and risk factors of residual deformities after total knee arthroplasty for valgus knee

背景:恢复下肢力线是人工全膝关节置换术(TKA)的重要目标之一。TKA术后力线受到包括术前畸形特点和手术方式选择等多方面因素的影响。目的:分析外翻膝TKA术后残留畸形的发生率及其危险因素。方法:回顾性分析2004~2016年接受TKA手术的外翻膝患者131例。在术前和术后下肢全长X线片上进行畸形分析。术后下肢整体机械轴外翻大于3°,定义为残留外翻畸形。收集患者年龄、性别、术前ASA分级、Charlson合并症指数和各种外翻膝分型(包括JST股骨分型和胫骨分型、Krackow分型、Ranawat分型、SOO分型)。采用二元Logistic回归分析筛选外翻膝行TKA术后残留畸形的危险因素。结果:共有47例(35.9%)外翻膝TKA术后残留外翻畸形,股骨侧残留畸形有37例(28.2%),胫骨侧残留畸形有12例(9.2%)。术后整体残留外翻畸形的独立危险因素是JST分型中的股骨侧不同亚型(P=0.005);F1b型残留畸形风险高于F1a和F2型(F1a比F1b,OR=0.12,P=0.0009;F2比F1b,OR=0.22,P=0.006);术后胫骨侧残留畸形的独立危险因素包括体重指数(OR=1.326,P=0.03)和术前胫骨畸形程度(OR=1.353,P=0.03)。结论:外翻膝接受传统TKA术后残留外翻畸形发生率超过1/3,股骨侧残留畸形较胫骨侧常见。JST分型系统的股骨侧分型是TKA术后残留外翻畸形的独立危险因素。根据外翻膝的畸形特点个体化选择手术方式,并提高手术精确度,可能是降低TKA术后残留外翻畸形的方法。

Background: Restoration of knee alignment is one of the mainstays of total knee arthroplasty(TKA). Knee alignment after TKA can be affected by many factors, including the characteristics of preoperative deformity and surgical procedures. Objective: To investigate the incidence and risk factors of residual deformities after TKA for valgus knee.Methods: A total of 131 patients with valgus knees who received TKA from 2004 to 2016 were retrospectively analyzed.Malalignment test was performed on full length X-ray of lower extremity taken preoperatively and postoperatively. Residual valgus deformity was defined as valgus mechanical axis greater than 3° after surgery. Age, sex, ASA score, Charlson’s comorbidity index and classification of valgus knee(including JST classification, Krackow’s classification, Ranawat’s classification and SOO classification) were obtained. Risk factors of residual valgus deformity after TKA were analyzed by binary logistic regression analysis. Results: Forty-seven knees(35.9%) had residual valgus deformity after TKA, 37 knees(28.2%) had residual valgus deformity on the femoral side, and 12 knees(9.2%) had residual valgus deformity on the tibial side. The independent risk factor of postoperative residual valgus deformity was different JST subtypes of femoral side(P=0.005);F1 b had significantly higher risk of residual deformity than F1 a or F2(F1 a versus F1 b, OR=0.12, P=0.0009;F2 versus F1 b, OR=0.22, P=0.006). The independent risk factors of postoperative residual deformity of tibia side were body mass index(OR=1.326, P=0.03) and degree of preoperative deformity on the tibial side(OR=1.353, P=0.03). Conclusions: The incidence of residual valgus deformity after TKA is more than 1/3, and it is more common in the femur than in the tibia. The femoral subtypes of JST classification are independently associated with postoperative residual deformity. Individualized surgical procedure according to the deformity classification of valgus knees may reduce the incidence of residual deformity.