Multifidus Degeneration: The Key Imaging Predictor of Adjacent Segment Disease.

Study Design: Retrospective cohort study.
Objectives: To identify imaging predictors on pre- and perioperative imaging that are associated with a future revision surgery for adjacent segment disease (ASD) following lumbar fusion.
Methods: Patients undergoing open posterior lumbar fusion between 2014-2022 were followed-up for >2-year. The initial MRI was evaluated for disc degeneration by Pfirrmann (grade 1-5); Modic changes (0-3); as well as fatty infiltration and functional cross-sectional area (fCSA) of the multifidus, erector spinae, and psoas. Spinopelvic alignment was measured pre- and postoperatively.
Results: Of 216 patients, 14.8% (n = 32) required revision surgery for ASD in the further course. There were no significant differences in Modic changes or Pfirrmann grades between the ASD group and controls. Fatty infiltration was significantly higher in the ASD group for both the erector spinae (40.5% vs 36.9%, P = 0.043) and multifidus muscles (61.0% vs 53.9%, P = 0.003). Additionally, the multifidus fCSA was smaller in patients who developed ASD (5.7 cm ² vs 6.7 cm ² ). Pre- and postoperative spinopelvic parameters were not significantly different between groups, and no other MRI measurements showed a significant difference. In a multivariable logistic regression model adjusting for age and sex, multifidus fatty infiltration emerged as the only significant predictor of ASD revision surgery ( P = 0.004). Patients with more than 58% multifidus fatty infiltration had over double the risk of developing ASD (OR 2.7, 95% CI: 1.1-6.5, P = 0.032).
Conclusions: Multifidus fatty infiltration is the key imaging predictor for the development of ASD requiring surgical revision. Disc degeneration and spinopelvic alignment appear to have less impact.
Competing Interests: Declaration of Conflicting InterestThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: AAS reports royalties from Ortho Development, Corp. DePuy Spine Products/Medical Device Business Services, Clariance, Inc.; private investments for Vestia Ventures MiRUS Investment, LLC, ISPH II, LLC, ISPH 3, LLC, and Centinel Spine (Vbros Venture Partners V); consulting fees from DePuy Spine Products/Medical Device Business Services, Clariance, Inc., Kuros Biosciences AG; speaking and/or teaching arrangements for DePuy Spine Products/Medical Device Business Services; membership of scientific advisory board of DePuy Spine Products/Medical Device Business Services, Kuros Biosciences AG, Clariance, Inc., and research support from Spinal Kinetics, Inc./Orthofix, Inc., outside the submitted work. FPC reports royalties from Accelus; ownership interest for 4WEB Medical/4WEB, Inc.; Healthpoint Capital Partners, LP; ISPH II, LLC; ISPH 3 Holdings, LLC; Ivy Health care Capital Partners, LLC; Medical Device Partners II, LLC; Medical Device Partners III, LLC; Orthobond Corporation; Spine Biopharma, LLC; Tissue Differentiation Intelligence, LLC; Tissue Connect Systems, Inc.; VBVP VI, LLC; VBVP X, LLC; Woven Orthopedics Technologies; consulting fees from Spine Biopharma, LLC, and Accelus; membership of scientific advisory board/other office of Healthpoint Capital Partners, Medical Device Partners II, LLC, Orthobond Corporation, Spine Biopharma, LLC, and Woven Orthopedic Technologies; and research support from 4WEB Medical/4WEB, Inc., Camber Spine, Choice Spine, DePuy Synthes, Centinel Spine, and Royal Biologics outside the submitted work. FPG reports royalties from Lanx, Inc. And Ortho Development Corp.; ownership interest in Centinel Spine, BICMD; consulting fees from Lanx, Inc, Ortho Development Corp, and Sea Spine;and stock ownership in Centinel Spine, Healthpoint Capital Partners, LP; membership of scientific advisory board/other office of Healthpoint Capital Partners, outside the submitted work. APH reports research support from Kuros Biosciences AG and Expanding Innovations, Inc.; private investments in Tissue Connect Systems, Inc.; and fellowship support from NuVasive, Inc., Globus Medical North America, Inc., and Alphatec Spine, Inc., outside the submitted work.