Cervical sarcopenia and frailty as complementary predictors of postoperative outcomes after odontoid fracture fixation: a retrospective cohort study in the United States.

Abstract

Retrospective cohort study. To compare three cervical sarcopenia metrics and frailty as preoperative predictors of unfavorable postoperative outcomes following surgical fixation of odontoid fractures. Sarcopenia is increasingly recognized as an indicator of physiologic vulnerability in spine surgery and thoracolumbar trauma. However, its prognostic significance in odontoid fractures remains unclear, and no previous study has directly compared cervical sarcopenia measurement sites in this population. Adult patients who underwent surgical fixation of traumatic odontoid fractures at a single level I trauma center were retrospectively reviewed. Sarcopenia was quantified on perioperative computed tomography using sternocleidomastoid, prevertebral, and paraspinal cross-sectional area normalized to the C3 vertebral body area. Frailty was assessed using the 5-factor modified frailty index (mFI-5), with hypertension status confirmed through a review of prescribed medications. Associations with postoperative outcomes were evaluated using threshold-based analyses, intercorrelation testing, subgroup analysis of combined low-sarcopenia/high-frailty patients, and an exploratory Combined Sarcopenia-Frailty Score. This study included 61 patients (mean age, 61.7 years; 50.8% female). The three sarcopenia metrics were only modestly intercorrelated (Spearman rho, 0.34-0.47), with 46.7%-53.3% overlap among patients in the most sarcopenic quartiles. No individual sarcopenia or mFI-5 threshold independently predicted postoperative outcomes. However, patients in the most sarcopenic quartile on any cervical metric with an mFI-5 ≥2 (n=11) experienced higher rates of mortality, urinary tract infection, pneumonia, and nonunion. In exploratory receiver operating characteristic analysis, the Combined Sarcopenia-Frailty Score exhibited moderate discrimination for significant adverse events, with an area under the curve of 0.73 and an optimal threshold of ≥9. Cervical sarcopenia and frailty were not independently associated with adverse outcomes following odontoid fracture fixation. However, their combination identified patients at substantially higher risk for mortality, complications, and nonunion, supporting a potential role for combined preoperative risk stratification (Level of Evidence: level III).