Spine Journal - 2026-08-01 - Journal Article
Postoperative muscle loss and preoperative sarcopenia predict survival and morbidity after surgical stabilization for spinal metastases: a longitudinal CT-morphometric analysis of 285 patients.
Kylies J, Leonhardt LG, Lenz M, Brauneck E, Schroeder M, Schomacher M, Dreimann M, Obid P, Viezens L
Topics
Key Takeaway
Postoperative SMI decline ≥15% independently predicted median survival of 284 vs 730 days (HR 4.78), and preoperative sarcopenia—present in one-third of patients—independently predicted mortality with HR 4.01 after surgical stabilization for spinal metastases.
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Summary
This study quantified CT-based skeletal muscle changes before and ~9 months after surgical stabilization for spinal metastases in 285 patients, comparing MIS vs open approaches and metastatic vs nononcologic fracture controls. Preoperative sarcopenia (one-third of cohort) independently predicted mortality (HR 4.01), prolonged LOS, and higher complication rates. MIS was associated with significantly less postoperative SMI decline than open surgery (-24% vs -40%, p<0.0001), and SMI decline ≥15% independently predicted survival (median 284 vs 730 days, HR 4.78).
Key Limitation
The retrospective single-center design introduces selection bias in who received follow-up CT at 9 months, potentially excluding early-mortality patients and systematically underestimating the true burden of postoperative muscle loss in the highest-risk cohort.
Original Abstract
BACKGROUND CONTEXT
Sarcopenia is associated with adverse outcomes in oncologic populations, yet the postoperative trajectory of skeletal muscle following spine surgery for metastatic disease remains poorly characterized.
PURPOSE
To quantify postoperative changes in CT-based body composition after surgical stabilization for spinal metastases and to evaluate the prognostic impact of preoperative sarcopenia and postoperative muscle decline.
STUDY DESIGN/SETTING
Retrospective cohort study at a tertiary spine center (2016-2024).
PATIENT SAMPLE
285 adults undergoing surgical stabilization for spinal metastases with preoperative CT (tCT1) and routine follow-up CT at approximately 9 months (tCT2).
OUTCOME MEASURES
Overall survival, length of stay, postoperative complications, ECOG performance status, and CT-based morphometric parameters at L3 (skeletal muscle index [SMI], paraspinal muscle index, psoas muscle index, VAT, SMD).
METHODS
CT morphometry was performed using standardized protocols. Preoperative sarcopenia was defined using validated sex-specific SMI thresholds. Receiver operating characteristic analysis identified ≥15% postoperative SMI decline as the optimal survival-related cutoff. Multivariable Cox models adjusted for clinical and oncologic covariates. A nononcologic fracture cohort undergoing lumbar stabilization was included to differentiate surgery-related muscle loss from cancer-related systemic catabolism.
RESULTS
Skeletal muscle mass and quality declined substantially after surgery, particularly following lumbar stabilization. Minimally invasive procedures were associated with significantly less muscle loss than open approaches (SMI decline -24% vs -40%, p<.0001). Compared with fracture controls, metastatic patients demonstrated markedly greater losses in muscle indices and a distinct pattern of visceral fat depletion. An SMI decline ≥15% independently predicted reduced survival (median 284 vs 730 days; hazard ratio 4.78) and poorer functional status. Preoperative sarcopenia, present in one-third of patients, also independently predicted mortality (hazard ratio 4.01), prolonged hospitalization, and higher complication rates.
CONCLUSIONS
Postoperative skeletal muscle loss after stabilization for spinal metastases is frequent and clinically meaningful. Both preoperative sarcopenia and postoperative SMI decline independently predict survival, supporting routine morphometric assessment and the adoption of muscle-sparing surgical and rehabilitation strategies.