What affects the surgical site segmental lordosis after MIS-TLIF?

Abstract

최근들어 최소칩습 추간공접근하 요추체간유합술에 대한 인기는 점점 늘어가고 있다. 케이지를 삽입하는 것이 전만각을 형성하는 데 있어 고식적인 유합술에 비해 최소칩습 추간공접근하 요추체간유합술에서 더 큰 비중을 차지한다. 우리는 이 연구에서 최소칩습 추간공접근하 요추체간유합술에서 전만각을 형성하는데 영향을 미치는 인자를 조사하고자 최소칩습 추간공접근하 요추체간유합술 시행후 전만각이 증가된 환자와 감소된 환자를 비교해보고자 하였다. 2018년 1월부터 2019년 9월까지 최소칩습 추간공접근하 요추체간유합술을 시행한 총 55명의 환자를 대상으로 연구를 수행하였다. 이 결과 전만각이 증가된 군(34명)은 감소된 군(21명)에 비해 수술레벨이 요추 3/4번 보다는 4/5번에 더 치우쳐있었다. (증가군 4/5 (94.1%), L3/4 (5.9%), 감소군 4/5(71.4%) , 3/4( 28.6%)) 수술레벨은 odds ratio 0.46(p =0.019)으로 3/4번일수록 수술후 수술레벨의 전만각이 감소했다. 또한 수술전 수술레벨의 전만각(12.40° vs. 16.31°) 과 근위부 전만각(9.40° vs. 15.86°)은 증가군에서 감소군에 비해 그 크기가 작았다. 수술레벨의 전만각이 커질수록 odds ratio 0.82( p =0.037)으로 수술후 수술레벨의 전만각이 감소했다. 근위부 전만각이 커질수록 odds ratio 0.68( p =0.028)으로 수술후 수술레벨의 전만각이 감소했다. 초록/요약more Recently, MIS-TLIF using a single cage has become popular. Cage insertion plays a major role in creating lordosis during MIS-TLIF compared with conventional interbody fusion. In this study, we sought to find out factors that affects segmental lordosis after MIS-TLIF by comparing patients whose segmental lordosis increased with those who experienced a decrease. A retrospective analysis was performed on 55 patients who underwent MIS-TLIF at our institute from January 2018 to September 2019. Demographic, pre- and postoperative radiologic and cage-related factors were included. The statistical analyses compared patients whose SL increased with decreased after surgery. After surgery, SL increased in 34 patients (group I) and decreased in 21 patients (group D). All preoperative and postoperative radiologic parameters differed significantly except Segmental Lordosis, Pelvic Incidence, and Distal Lumbar Lordosis. The index level, Disc Lordosis (DCL), Segmental Lordosis (SL), Lumbar Lordosis (LL), Proximal Lumbar Lordosis (PL), and Y axis position of the cage center differed significantly between groups I and D. In group I, the index level was more often L4/5 (94.1%) than L3/4 (5.9%) compared with group D (71.4% and 28.6%). DCL (5.15° vs. 8.27°), SL (12.40° vs. 16.31°). LL (41.29° vs. 47.28°), and PL (9.40° vs. 15.86°) were significantly smaller in group I than group D. The cage in group I was more anterior than in group D (cage Y axis: 55.84 vs. 51.24). The multivariate analysis showed that SL decreased more significantly after MIS- TLIF when the index level was L3/4 than when it was L4/5 (OR: 0.46, p =0.019), as preoperative SL (OR: 0.82, p =0.037) or PL (OR: 0.68, p =0.028) increased, and as the cage became more anterior (OR: 1.10, p =0.032). Changes in SL after MIS-TLIF are associated with preoperative SL and PL, the index level, and the Y axis position of the cage. An index level at L4/5 instead of L3/4, smaller preoperative SL or PL, and an anterior position for the cage are likely to result in increased SL after MIS-TLIF.