Spine - 2026-06-24 - Journal Article
Full-Body Radiographic Imaging-Based Thigh Muscle Measurement for Sarcopenia: Association with Functional Assessments and Sagittal Alignment in Adult Spinal Deformity Patients.
Nassar JE, Farias MJ, Hostin R, Gupta MC, Klineberg EO, Mundis GM, Okonkwo DO, Hamilton KD, Passias PG, Protopsaltis TS, Kim HJ, Gum JL, Smith JS, Raad M, Kebaish KM, Lenke LG, Shaffrey CI, Bess S, Schwab FJ, Lafage R, Lafage V, Daniels AH, Diebo BG, International Spine Study Group
Topics
Key Takeaway
EOS-derived sarcopenia (11.3% prevalence in ASD patients) independently associates with greater SVA (β=13.17), thoracic kyphosis (β=6.87), and cervical lordosis (β=5.84), reflecting a shift toward distal compensatory mechanisms.
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Summary
This multicenter retrospective study of 540 ASD patients from 24 centers asked whether EOS-derived thigh and quadriceps muscle thickness identifies sarcopenia and whether sarcopenic status correlates with functional measures and compensatory sagittal alignment. Sarcopenic patients (11.3%) had lower BMI (23.6 vs. 27.3 kg/m²), higher frailty scores (3.4 vs. 3.0), and slower TUG (12.2 vs. 10.5s). Sarcopenia correlated with greater SVA, thoracic kyphosis, and cervical lordosis but not pelvic tilt or sacro-femoral angle, suggesting exhausted proximal compensation with preserved distal recruitment.
Key Limitation
Cross-sectional design cannot establish causality between sarcopenia and compensatory alignment patterns, limiting prognostic application to postoperative outcomes.
Original Abstract
STUDY DESIGN
Multicenter retrospective cohort study of prospectively collected data.
OBJECTIVE
Evaluate the impact of EOS-derived thigh muscle measurements as indicators of sarcopenia and their effect on compensatory mechanisms in adult spinal deformity (ASD) patients.
SUMMARY OF BACKGROUND DATA
ASD patients frequently present with sarcopenia, the progressive loss of muscle strength and mass associated with worse postoperative outcomes. Routine EOS full-body radiographs allow opportunistic thigh muscle measurement without added cost or radiation. This study evaluated EOS-derived thigh and quadriceps thickness against clinical indicators of sarcopenia and their impact on compensatory mechanisms in ASD.
METHODS
We retrospectively analyzed prospectively collected data from 24 U.S. and Canadian spine centers(2019-2024). Sarcopenia was defined using validated sex-specific EOS cutoffs. Patients were classified as sarcopenic only when both AP thigh and LAT quadriceps measurements fell below threshold. Clinical frailty scores, grip strength, 3-meter timed up and go(TUG), and epigenetic age were compared between sarcopenic(SARCO) and non-sarcopenic(NON-SARCO) patients. Multivariate regressions assessed associations between thigh measurements, sarcopenia status, and compensatory radiographic parameters.
RESULTS
Among 540 ASD patients (mean age 60, 71% female), 61 (11.3%) were SARCO. SARCO patients had lower BMI(23.6 vs. 27.3 kg/m²), higher clinical frailty scores (3.4 vs. 3.0), and slower TUG (12.2 vs. 10.5s) (all P<0.05). Multivariate analyses showed smaller thigh and quadriceps thickness and sarcopenia status correlated with higher frailty, weaker grip, slower TUG, and older epigenetic age (all P<0.05). Sarcopenia was also associated with greater thoracic kyphosis (β=6.87, P<0.01), cervical lordosis (β=5.84, P=0.01), sagittal vertical axis (β=13.17, P=0.04), and knee flexion angle (β=2.29, P=0.04), but not pelvic tilt, shift, or sacro-femoral angle (all P>0.05).
CONCLUSIONS
Full-body radiographic derived thigh measurements significantly correlate with frailty, grip strength, TUG, and epigenetic age. Sarcopenic ASD patients demonstrate impaired proximal and increased distal compensations. Incorporating thigh and quadriceps muscle thickness measurements into preoperative assessment may improve surgical planning and patient management in ASD.
LEVEL OF EVIDENCE
Prognostic Level III.