Association Between Timing of Preoperative Magnetic Resonance Imaging (MRI) and Postoperative Outcomes After Lumbar Decompression: A Propensity-Matched Cohort Study

Background: Magnetic resonance imaging (MRI) is routinely used in preoperative planning for lumbar decompression, yet the optimal timing of imaging prior to surgery remains unclear. Variability in MRI timing may reflect differences in care pathways and could influence postoperative outcomes. Objective: This study aims to evaluate the association between the timing of preoperative MRI and postoperative outcomes following lumbar decompression. Methods: A retrospective cohort study was conducted using the TriNetX Global Collaborative Network (TriNetX, LLC, Cambridge, MA). Adult patients undergoing lumbar decompression for degenerative lumbar spine pathology were stratified based on timing of preoperative MRI: 31-90 and <30 days prior to surgery. Propensity score matching (1:1) was performed to balance baseline characteristics. Outcomes assessed within one year included reoperation, postoperative infection, and neurologic complications. Results: After matching, 37,245 patients per cohort were included. There were no significant differences in reoperation (1.7% vs. 1.8%, risk ratio (RR) = 0.94, p = 0.46) or neurologic complications (0.1% vs. 0.1%, RR = 0.89, p = 0.56). Patients undergoing MRI 31-90 days prior to surgery had significantly lower rates of postoperative infection compared with those imaged within 30 days (2.7% vs. 3.3%, RR = 0.81, p < 0.001). Conclusion: Timing of preoperative MRI was not associated with reoperation or neurologic complications following lumbar decompression. However, an MRI performed 31-90 days prior to surgery was associated with lower postoperative infection rates, suggesting that the timing of imaging may reflect underlying care pathways rather than a causal relationship.