Factors Associated with Early Postoperative Pain after Lateral Lumbar Interbody Fusion

Introduction: Despite that lateral lumbar interbody fusion (LLIF) is a minimally invasive surgery, some patients complain of severe site pain immediately after the surgery. This study aimed to explore the extent of perioperative pain after LLIF, compare the degree of perioperative pain after LLIF with that after other surgical procedures, and evaluate the factors associated with severe pain in the early postoperative period. Methods: In this study, 93 patients who underwent lumbar spine surgeries for lumbar degenerative diseases were analyzed. The patients were categorized into three groups based on the surgical procedure: Group L, LLIF with percutaneous pedicle screw (PPS); Group P, posterolateral fusion (PLF) or posterior lumbar interbody fusion (PLIF); and Group D, posterior decompression (fenestration). The extent of low back pain was evaluated using the visual analog scale (VAS) preoperatively and from postoperative days 1 to 14. Results: The VAS score for postoperative pain decreased in a time-dependent manner in all three groups (P<0.01). Repeated measures analysis of variance (ANOVA) showed that the VAS in Group L was significantly higher than that in Group D (P<0.01). Time point analysis revealed that the VAS scores from postoperative days 1 to 9 in Group L were significantly higher than those in Group D (P<0.05). No significant difference was observed in the VAS scores of postoperative pain between Groups L and P on all postoperative days. The VAS score for early postoperative pain in Group L was significantly correlated with the change in disc height index (P<0.05, r=0.43) and tended to be associated with the grade of preoperative disc degeneration and the VAS score of preoperative low back pain (P=0.076-0.19). Conclusions: This study is the first to evaluate the factors associated with pain during the early postoperative period of LLIF. Although LLIF is a minimally invasive surgery, severe pain may develop in patients with significant preoperative disc degeneration or following spinal correction surgery.