Clinical Trajectory for Patients with Predominant Back Pain versus Predominant Leg Pain Undergoing Lateral Lumbar Interbody Fusion with Posterior Instrumentation

Introduction: The influence of predominant pain location for patients undergoing lateral lumbar interbody fusion with posterior instrumentation (LLIF+P) has not been well studied. We aim to examine the influence of preoperative predominant back pain (pBP) versus predominant leg pain (pLP) on the postoperative clinical trajectory through patient-reported outcome measures (PROMs) and minimum clinically important difference (MCID) in patients undergoing LLIF+P.

Methods: Retrospective review of a single-surgeon database for patients undergoing LLIF+P with preoperative visual analog scale (VAS) back and VAS leg scores was conducted. Patients were separated into pBP and pLP cohorts. Demographics, perioperative outcomes, and PROMs of Patient-Reported Outcomes Measurement Information System Physical Function (PROMIS-PF), 12-Item Short Form Physical Composite Score (SF-12 PCS), VAS back, VAS leg, and Oswestry Disability Index (ODI) were collected at preoperative and postoperative 6-week/12-week/6-month/1-year/2-year time points. MCID was determined through comparison of previously established MCID thresholds. Demographics, perioperative outcomes, PROMs, and MCID were compared among groups through inferential statistics, and postoperative PROM improvement was calculated through paired sample t-test.

Results: Eighty patients were identified. More patients with pBP had single-level fusion and reported higher postoperative day (POD) 1 pain scores (p≤0.040, both). Regardless of predominant pain location, patients reported significant postoperative improvement in all PROMs (p≤0.045, all). More patients with pBP achieved MCID in physical function, back pain, and disability outcomes (p≤0.049, all).

Conclusion : Patients independent of predominant pain location reported significant improvement in physical function, pain, and disability outcomes. Patients with predominant back pain had higher rates of MCID achievement in physical function, back pain, and disability outcomes. More patients with predominant back pain undergoing LLIF with posterior instrumentation may experience clinically meaningful improvement.