Evaluation of bony fusion after posterior lumbar interbody fusion: a systematic review and meta-analysis.

INTRODUCTION

Posterior lumbar interbody fusion (PLIF) is a common surgical procedure for degenerative lumbar conditions, aiming to decompress neural tissue and stabilize the spine. Bony fusion is essential for long-term success, but inconsistent radiological criteria lead to variable reported fusion rates. This systematic review and meta-analysis evaluated quantitative criteria for assessing bony fusion and their impact on fusion rates over time.

RESEARCH QUESTION: What quantitative criteria are used to assess bony fusion after PLIF, and how do these criteria affect fusion rates at different postoperative time points?

MATERIAL AND

METHODS

PubMed, MEDLINE, Embase, Web of Science, Cochrane Library, and CINAHL were searched through November 6, 2025, for studies assessing bony fusion after PLIF using quantitative criteria on dynamic X-ray or CT. Pooled fusion rates were calculated at different postoperative time points, including additional analyses for cage material, smoking, and segmental motion cut-offs.

RESULTS

Seventeen studies including 1390 patients were analyzed. Fusion was assessed quantitatively exclusively by dynamic X-ray. Pooled fusion rates increased over time: 76.0% at 6 months, 86.4% at 12 months, 90.2% at 24 months, and 93.4% at 48 months. Optimal cut-off values for segmental motion of ≤3° and ≤4° were chosen due to similar heterogeneity, which was the lowest at 24 months.

DISCUSSION AND

CONCLUSION

Fusion rates reach approximately 90% 24 months after PLIF and show minimal increase thereafter. Evaluating segmental motion with a ≤3°- or ≤4° cut-off provides the most reliable assessment of bony fusion.