Preoperative Factors Affecting the Two-Year Postoperative Outcome in Single-Level Lumbar Grade I Degenerative Spondylolisthesis: Prospective, Multicenter, Patient-Preference Cohort Study using Patient-Reported Assessment

Background: Selection of operative method for lumbar spinal stenosis with Meyerding grade I degenerative spondylolisthesis remains controversial and the preoperative factors affecting the patient-reported postoperative assessment are unknown. The objective of this study was to clarify the preoperative factors affecting the two-year postoperative outcome in Meyerding grade I degenerative spondylolisthesis by using a patient-reported assessment. Methods Seventy-two consecutive patients who had decompression alone (D group; 28) or with fusion (DF group; 44) were enrolled. The parameters investigated were the Japanese Orthopaedic Association back pain evaluation questionnaire, visual analog scales, and radiological evaluation of L4 slippage (L4S), lumbar lordosis (LL), and lumbar axis sacral distance (LASD) as an index of sagittal alignment. The prospectively collected data of postoperative 2 years were examined by statistical analysis. Results Finally, sixty-two cases (D group; 25, DF group; 37) were evaluated. There was no significant difference in JOABPEQ outcome between the two surgical groups. On the other hand, in multiple logistic regression analysis, gender, preoperative L4S, LASD, and LL were extracted as significant preoperative factors affecting the two-year postoperative outcome. Women had a lower rate of improvement in lumbar spine dysfunction due to low back pain (risk ratio = 0.17, p = 0.034) and psychological disability (risk ratio = 0.222, p = 0.045) compared to men. Patients with preoperative L4S greater than 5–6 mm have a lower rate of improvement in low back pain (risk ratio = 0.159, p = 0.049) and lumbar spine dysfunction due to low back pain (risk ratio = 0.188, p = 0.043). Patients with a preoperative LASD greater than 30 mm have a higher rate of improvement in postoperative low back pain (risk ratio = 20.905, p = 0.008) and lumbar dysfunction due to low back pain (risk ratio = 11.48, p = 0.021). Preoperative LL of less than 35 degrees was associated with a lower rate of improvement in gait disturbance due to low back pain (risk ratio of high lordosis to low lordosis = 11.638, p = 0.017). Conclusions In this study, the selection of operative method was not a significant factor affecting the two-year postoperative outcome and gender, preoperative L4S, LASD, and LL were extracted as significant preoperative factors.