Clinical Outcomes of Additional Posterior Lumbar Interbody Fusion for Adjacent Segment Disease after Posterior Lumbar Interbody Fusion Assessed with the Zurich Claudication Questionnaire

A retrospective analysis of prospectively collected data.The Zurich Claudication Questionnaire (ZCQ) has been recently reported to be the most responsive assessment tool for lumbar spinal stenosis among the ZCQ, the Oswestry Disability Index, the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire, the visual analog scale, the 8-Item Short Form Health Survey, and the EuroQol 5 dimensions 5 level. There has been no study comparing surgical outcomes of additional posterior lumbar interbody fusion (PLIF) for adjacent segment disease (ASD) after previous PLIF with those of primary PLIF.We compared the clinical outcomes of additional PLIF for unstable ASD after previous PLIF with those of primary PLIF assessed with the ZCQ to examine whether surgical outcomes of additional PLIF for ASD following previous PLIF are inferior to those of primary PLIF.Thirteen consecutive patients undergoing additional single-level PLIF for unstable ASD after previous PLIF (A group) and 61 consecutive patients undergoing primary single-level PLIF (P group) were included in the study. Clinical outcomes were assessed with the ZCQ before PLIF surgery and at 2 years postoperatively. Achievement rates of the minimum clinically important difference (MCID) of each domain (symptom severity [SS] and physical function [PF]) on the ZCQ were evaluated in each group.In the A group, the mean SS and PF before additional PLIF were 3.615 and 3.1, respectively, which significantly improved to 2.231 and 2.0, respectively, at 2 years after surgery. In the P group, the mean SS and PF before primary PLIF were 3.438 and 2.5, respectively, which also significantly improved to 2.194 and 1.6, respectively, at 2 years postoperatively. PF before additional PLIF in the A group was significantly inferior to that in the P group, but SS both before and after PLIF and PF at 2 years postoperatively showed no significant differences between the two groups. The achievement rates of the MCID of SS and PF were 92.3 and 76.9%, respectively, in the A group and 59.0 and 59.0%, respectively, in the P group. The MCID achievement rates of SS was significantly higher in the A group than in the P group.Assessed with the ZCQ at 2 years after surgery, the clinical outcomes of additional single-level PLIF for unstable ASD after previous PLIF were equivalent to those of primary single-level PLIF.