垫片后倾角对后交叉韧带保留型全膝置换术关节内应力分布的影响

Role of polyethylene insert posterior slope on intra-articular stress distribution during cruciate ligament retaining total knee arthroplasty

[目的]比较不同后倾及不对称后倾的聚乙烯垫片对于后交叉保留型全膝关节置换(CR-TKA)术关节内应力分布的影响。[方法]2016年1月~2017年8月在本中心行全膝关节置换患者共40例(40膝)纳入本研究,其中男性16例,女性24例。根据Vanguard CR-TKA垫片的标准型(CR-TKA-SI)的外侧半与厚唇型(CR-TKA-LI)的内侧半,设计后倾不对称型聚乙烯垫片(CR-TKA-APSI)并制作三种垫片的智能试模,使用膝关节置换术中无线应力检测系统(WFMS)分别测量三种不同形态的垫片放入后膝关节内外侧间室的应力分布情况。[结果]术中关节内总应力分布:三种形态的垫片关节内总应力屈曲过程中均逐渐减小,0°~45°时三组间总应力差异无统计学意义(P>0.017),60°~120°时CR-TKA-LI组的关节内总应力显著高于CR-TKA-SI组与CR-TKA-APSI组(P<0.017)。术中关节内外侧间室应力分布:0°~45°三组间内侧间室占总应力比例无显著差异,屈曲60°~120°时CR-TKA-APSI组内侧间室应力占总应力百分比为41.68%~66.82%,显著高于CR-TKA-SI与CR-TKA-LI组。[结论]内外侧后倾角相同的垫片,在整体后倾角改变时,可以调整CR型全膝关节屈曲位的软组织总体张力情况,但不会显著改变内外侧关节应力分布比例;而内外侧不对称后倾的垫片可起到调节屈曲位关节内应力分布的作用。

[Objective] To explore the role of polyethylene insert posterior slope on intra-articular stress distribution in cruciate retaining total knee arthroplasty（CR-TKA）.[Methods] From Jan 2016 to Aug 2017,40 patients（40 knees） who underwent CR-TKA in our hospital were enrolled into this study,including 16 males and 24 females.Based on Vanguard CR-TKA insert,a CR-TKA polyethylene insert with asymmetric posterior slope insert（CR-TKA-APSI） was made by combining the lateral half of CR-TKA standard insert（CR-TKA-SI） and the medial half of CR-TKA lipped insert（CR-TKA-LI）.In addition,the smart trials of the three types of inserts were made.During operation the intra-articular stress distribution of CR-TKA were recorded at 0°,30°,45°,60°,90° and 120° of knee flexion using the Wireless Force Measurement System（WFMS）.[Results]The total intra-articular force in all the 3 groups significantly decreased from 0° to 120° of knee flexion.The CR-TKA-LI group was significantly superior to the other two groups from 60° to 120° of flexion（P〉0.017）,but no significant differences were found from 0° to 45° of flexion（P〈0.017）.The percentage of medial compartment force out of total force was significantly higher in the CR-TKA-APSI group（41.68%~66.82%） than the other two groups form 60° to 120° of flexion,but not from 0° to45° of flexion.[Conclusion] For CR-TKA polyethylene inserts with the same posterior slope in the medial and lateral plateaus,the total intra-articular forces during knee flexion could be adjusted by different posterior slope angles,without significantly altering the force distribution patterns.Polyethylene inserts with differential posterior slope angles in the medial and lateral plateaus could serve the purpose to adjust the force distribution in the medial and lateral compartments during flexion of CR-TKA.