经股内侧肌入路全膝关节置换术中髌骨位置对软组织平衡及临床疗效的影响

Influence of patella position on soft tissue balance and clinical outcomes in patients undergoing total knee arthroplasty via a midvastus approach

目的探讨经股内侧肌入路全膝关节置换术中髌骨位置对软组织平衡及术后疗效的影响。方法纳入2018年12月至2019年2月收治的拟行初次经股内侧肌入路全膝关节置换术的患者55例,采用随机数字表法随机分为两组,术中分别采用髌骨复位下间隙平衡技术及髌骨半脱位下间隙平衡技术进行截骨和软组织平衡。比较完成截骨和软组织平衡后髌骨复位组与髌骨半脱位组及髌骨半脱位组髌骨复位前后的伸直、屈曲90°关节间隙及间隙内外翻角度;比较两组患者术后股骨假体旋转角及下肢机械轴线夹角,术后1、3、6个月的膝关节协会评分(Knee Society Score,KSS)、疼痛视觉模拟评分(visual analogue scale,VAS)、膝关节活动度的差异。结果55例均完成半年随访,髌骨复位组27例,髌骨半脱位组28例。术中完成截骨和软组织平衡后,髌骨复位组与髌骨半脱位组伸直和屈曲90°的关节间隙和内外翻角度的差异无统计学意义(P>0.05)。而髌骨半脱位组髌骨复位前屈曲90°的关节间隙为(10.5±0.3)mm,小于髌骨复位后的(11.0±0.3)mm,差异有统计学意义(t=4.180,P<0.001);屈曲90°的内翻角度为1.5°±0.3°,小于髌骨复位后的2.3°±0.4°,差异有统计学意义(t=7.642,P<0.001);髌骨半脱位组内髌骨复位前后伸直状态下的关节间隙和内外翻角度的差异无统计学意义(P>0.05)。术后髌骨半脱位组股骨假体旋转角为-0.49°±1.2°,小于髌骨复位组的0.24°±1.3°,差异有统计学意义(t=2.116,P=0.039)。术后1个月髌骨复位组膝关节活动度为109.6°±8.5°,高于髌骨半脱位组的104.9°±8.6°,差异有统计学意义(t=2.048,P=0.046);术后3个月和6个月时两组膝关节活动度的差异均无统计学意义(P>0.05)。术后1、3、6个月两组KSS评分和VAS评分的差异无统计学意义(P>0.05)。结论经股内侧肌入路全膝关节置换术中在髌骨脱位状态下进行软组织平衡有髌骨复位后屈曲间隙增大、内翻增加及股骨假体内旋增加的风险。在髌骨复位状态下进行软组织平衡术后早期活动度更好。

Objective To compare the effects of patellar position on the balance of soft tissue during the operation and the postoperative outcomes in minimally invasive total knee arthroplasty via a midvastus approach.Methods From December 2018 to February 2019,a total of 55 patients were enrolled for primary total knee arthroplasty via a midvastus approach.All patients were randomly divided into 2 groups by random number table.During the operation,the gap balance technique was used with patella reduced or subluxated to complete the osteotomy and balance of soft tissue.The changes of gap and varus-valgus angle were compared between the patellar reduction group and the patellar subluxation group in both extension and flexion position.These data were also compared before and after reducing patellar in the patellar subluxation group.Furthermore,the differences of femoral prosthesis rotation,mechanical femoral axis to tibial axis angle,Knee Society score(KSS),visual analogue scale(VAS)and range of motion(ROM)were compared between the two groups.Results All patients finished 6 months follow-up,including 27 patients in the patellar reduction group and 28 patients in the patellar subluxation group.After osteotomy and soft tissue balance during the operation,there was no significant difference in gap and varus-valgus angle between two groups in either extension or flexion position.While in the patellar subluxation group,the flexion gap was 10.5±0.3 mm with patella subluxated,less than 11.0±0.3 mm after reducing the patella.The varus-valgus angle was 1.5±0.3 with patella subluxated,less than 2.3±0.4 degree after reducing the patella.The difference was statistically significant(t=4.180,P<0.001;t=7.642,P<0.001).There was no significant difference in extension gap and varus-valgus angle before and after patella reduction in the patellar subluxation group(P>0.05).The rotation angle of the femoral component in the patellar subluxation group was-0.49°±1.2°,and the external rotation angle was smaller than that in the patellar reduction group(0.24°±1.3°).The difference was statistically significant(t=2.116,P=0.039).At one month after operation,ROM of the patellar reduction group was 109.6°±8.5°which was higher than that of the patellar subluxation group(104.9°±8.6°,t=2.048,P=0.046).There was no significant difference in ROM between the two groups at 3 and 6 months(P>0.05).Moreover,there was no significant difference in KSS and VAS at 1,3 and 6 months after operation(P>0.05).Conclusion In the minimally invasive total knee arthroplasty,it is suggested to balance the soft tissue as much as possible with the patellar reduced.Otherwise,the consequence of increased flexion space,increased varus and increased internal rotation of femoral prosthesis should be considered.The patients undergoing soft tissue balance with patella reduced have better ROM in the early stage postoperatively.