股骨后髁偏距与股骨后滚距离对后交叉韧带切除旋转平台型假体人工全膝关节置换术后膝关节屈曲度的影响

INFLUENCE OF POSTERIOR CONDYLAR OFFSET AND ANTEROPOSTERIOR FEMOROTIBIAL TRANSLATION ON KNEE FLEXION AFTER POSTERIOR CRUCIATE-SACRIFICING SELF ALIGNMENT BEARING TOTAL KNEE ARTHROPLASTY

目的观察采用后交叉韧带(posterior cruciate ligament,PCL)切除旋转平台型假体行人工全膝关节置换术(total knee arthroplasty,TKA)后股骨相对于胫骨的前后运动模式和股骨后髁偏距(posterior condylar offset,PCO)的变化,探讨二者对膝关节屈曲度(range offlexion,ROF)的影响。方法回顾分析2007年1月-2009年6月40例40膝采用PCL切除旋转平台型假体行TKA患者的临床资料。男18例,女22例;年龄56～87岁,平均70.6岁。病程5～14年,平均9.1年。左膝11例,右膝29例。术前膝关节外科学会评分(KSS)为(48.0±5.5)分,ROF为(77.9±9.0)°。手术前后摄X线片测量PCO及股骨后滚距离,以术后最大屈膝时股骨后滚距离和PCO的变化值为自变量,以膝关节最大ROF的改善值为因变量,进行多元逐步回归分析。结果术后切口均Ⅰ期愈合。患者均获随访,随访时间12～19个月,平均14.7个月。末次随访时KSS评分为(91.9±3.7)分,与术前比较差异有统计学意义(t=—77.600,P=0.000);临床效果优良。末次随访时ROF为(102.0±9.3)°,与术前比较差异有统计学意义(t=—23.105,P=0.000)。术前PCO为(31.6±5.5)mm,末次随访时为(30.6±5.9)mm,差异有统计学意义(t=3.565,P=0.001)。术后末次随访时股骨后滚距离为(—1.2±2.1)mm,95%可信区间为—1.9～—0.6 mm;27例(67.5%)发生矛盾性前移,1例(2.5%)位移为0 mm,12例(30.0%)出现后移。经多元逐步回归分析,回归方程成立(R=0.785,R2=0.617,F=61.128,P=0.000),股骨后滚距离可纳入方程(t=7.818,P=0.000),但PCO被剔除(t=1.471,P=0.150),最终得到的回归方程为y=25.587+2.349x。结论 采用PCL切除旋转平台型假体行TKA术后的股胫运动学多表现为屈膝过程中股骨相对胫骨的矛盾性前移,它是限制术后膝关节ROF的因素之一;术后PCO改变与术后ROF无相关性。

Objective To observe the posterior condylar offset （PCO） changes and anteroposterior femorotibial translation, to investigate the influence of them on the maximum knee range of flexion （ROF） in patients with posterior cruciate-sacrificing self alignment bearing total knee arthroplasty （TKA）. Methods The clinical data were analyzed retrospectively from 40 patients （40 knees） undergoing primary unilateral TC-PLUSTM SB posterior cruciate-sacrificing self alignment and bearing TKA for osteoarthritis between January 2007 and June 2009. There were 18 males and 22 females with an average age of 70.6 years （range, 56-87 years）. The disease duration was 5-14 years （mean, 9.1 years）. The locations were the left side in 11 cases and the right side in 29 cases. Preoperative knee society score （KSS） and ROF were 48.0± 5.5 and （77.9± 9.0）°, respectively. The X-ray films were taken to measure PCO and anteroposterior femorotibial translation. Multiple regression analysis was performed based on both the anteroposterior femorotibial translation and PCO changes as the independent variable, and maximum knee flexion as the dependent variable. Results All incisions healed by first intention. The patients were followed up 12-19 months （mean, 14.7 months）. At last follow-up, there were significant differences in the KSS （91.9± 3.7, t=— 77.600, P=0.000）, the ROF [（102.0± 9.3）°, t=— 23.105, P=0.000] when compared with preoperative values. Significant difference was observed in PCO （t=3.565, P=0.001） between before operation [（31.6± 5.5） mm] and at last follow-up [（30.6± 5.9） mm]. At last follow-up, the anteroposterior femorotibial translation was （— 1.2± 2.1） mm （95%CI： — 1.9 mm to — 0.6 mm）; femoral roll forward occurred in 27 cases （67.5%）, no roll in 1 case （2.5%）, and femoral roll back in 12 cases （30.0%）. By multiple regression analysis （Stepwise method）, the regression equation was established （R=0.785, R2=0.617, F=61.128, P=0.000）. Anteroposterior femorotibial translation could be introducted into the equation （t=7.818, P=0.000）, but PCO changes were removed from the equation （t=1.471, P=0.150）. Regression equation was y=25.587＋2.349x. Conclusion Kinematics after TC-PLUSTM SB posterior cruciate-sacrificing self alignment bearing TKA with posterior cruciate ligament-sacrificing show mostly roll forward of the femur relative to the tibia, which have a negative effect on postoperative range of motion. There is no correlation between PCO changes and postoperative change in ROF in TC-PLUSTM SB posterior cruciate-sacrificing self alignment bearing TKA.