Time Course of Functional Recovery Following Single-Level Anterior Lumbar Interbody Fusion with and Without Posterior Instrumentation: A Retrospective Single-Institution Study

<b>Background/Objectives</b>: While anterior lumbar interbody fusion (ALIF) is a well-established treatment for degenerative lumbar spine pathology, the timing and pace of postoperative recovery remain poorly defined. Understanding these temporal trends is clinically important for setting patient expectations and optimizing postoperative care. <b>Methods</b>: This retrospective single-institution study evaluated functional recovery in patients undergoing primary, single-level stand-alone (SA) ALIF, or with percutaneous posterior instrumentation (PI). Patient-reported outcome measures (PROMs), including the Oswestry Disability Index (ODI), the Visual Analog Scale (VAS) for back and leg pain, and the SF-12 Physical Component Score (PCS), were assessed preoperatively and at 2 weeks, 6 weeks, 3 months, 6 months, 1 year, and 2 years postoperatively. Achievement of minimum clinically important difference (MCID), global rating change (GRC), and return-to-activity milestones were also analyzed. <b>Results</b>: A total of 143 patients were included (90 SA; 53 PI). PROMs showed significant improvement through 1 year. VAS-back improved by 2 weeks, while ODI and SF12 PCS initially worsened but improved after 6 weeks. By 6 months, over half of the cohort achieved MCID, with continued gains through 1 year. Most patients returned to driving and work, and over 90% discontinued narcotics. Recovery trajectories were comparable between groups, despite early delays in the instrumented cohort. <b>Conclusions</b>: These findings provide time-specific recovery benchmarks that can guide surgical decision-making, patient education, and expectations around functional milestones.