Sarcopenia Predicts Early Adjacent Segment Disease Development Following Anterior and Oblique Lumbar Interbody Fusion

Introduction: Adjacent segment disease (ASD) is a common complication of spinal fusion surgery. We sought to determine whether sarcopenia, defined as a bilateral Psoas:Vertebral Body Ratio (P: VBR) > 1 SD below the gender mean in our study population, increases the risk of ASD following retroperitoneal approaches for lumbar interbody fusion (e.g. anterior [ALIF] or oblique lateral [OLIF]).

Methods: Retrospective data was collected from 104 adult patients > 18 years old who underwent short-segment fusion via ALIF or OLIF approach from 2013-2023. The primary outcome was development of ASD within 3 years of surgery. Patients who had prior surgery for ASD, underwent long-construct deformity correction, had an ongoing oncologic process, or lacked sufficient follow-up were excluded. Psoas and vertebral body volumetric measurements were calculated at the L4 pedicle level using preoperative MRI. Spinopelvic parameters of pelvic tilt (PT), pelvic incidence (PI), lumbar lordosis (LL), and PI-LL mismatch were recorded from standing upright radiographs. Odds ratios were calculated with logistic regression analyses.

Results: Out of 104 patients undergoing fusion via retroperitoneal approaches, 25 (24.04%) developed ASD within 3 years. Patient demographics and medical comorbidities did not predict early ASD. Left and right psoas area (cm2) and P:VBR strongly predicted ASD development (p < 0.0001). 19 patients were categorized as sarcopenic. 16 of the 19 sarcopenic patients developed ASD within 3 years, compared to 9 of the 85 non-sarcopenic patients (84.21% vs 10.59%, p< 0.0001). Postoperative PT and PI-LL mismatch were predictive of ASD on univariate but not multivariate analysis.

Conclusion : Sarcopenia significantly predicts ASD development within 3 years following lumbar fusion via retroperitoneal approaches. Sarcopenia is a risk factor for ASD formation and should be evaluated pre-operatively. Morphometric analysis provides a simple screening tool and can be used to tailor pre- and postoperative therapies to improve outcomes.