Multifidus Degeneration: The Key Imaging Predictor of Adjacent Segment Disease

Area of Science:

• Spine Surgery
• Radiology
• Biomedical Engineering

Background:

• Adjacent segment disease (ASD) is a common complication following lumbar fusion surgery.
• Identifying reliable predictors for ASD is crucial for improving patient outcomes and reducing revision rates.
• Pre- and perioperative imaging findings may offer insights into the risk of developing ASD.

Purpose of the Study:

• To identify imaging predictors on pre- and perioperative imaging associated with future revision surgery for adjacent segment disease (ASD) after lumbar fusion.
• To evaluate the role of MRI-based muscle characteristics and spinopelvic alignment in predicting ASD.

Main Methods:

• Retrospective cohort study of 216 patients undergoing open posterior lumbar fusion (2014-2022).
• Preoperative MRI analysis included Pfirrmann disc degeneration, Modic changes, multifidus and erector spinae muscle fatty infiltration, and functional cross-sectional area (fCSA).
• Pre- and postoperative spinopelvic alignment parameters were measured; patients were followed for >2 years for revision surgery due to ASD.

Main Results:

• 14.8% of patients required revision surgery for ASD.
• Higher multifidus (61.0% vs 53.9%, P=0.003) and erector spinae (40.5% vs 36.9%, P=0.043) fatty infiltration were significantly associated with ASD.
• Multifidus fatty infiltration was the sole significant predictor of ASD revision surgery in multivariable analysis (P=0.004); >58% infiltration doubled the risk (OR 2.7).

Conclusions:

• Multifidus fatty infiltration on preoperative MRI is a significant imaging predictor for developing adjacent segment disease requiring surgical revision after lumbar fusion.
• Disc degeneration and spinopelvic alignment showed less impact on ASD development compared to multifidus muscle quality.
• Targeting muscle quality may be a future strategy to mitigate ASD risk.