Masseter Sarcopenia and Mortality After Type II Odontoid Fractures in the Elderly: A 5-Year Follow-Up Study

BACKGROUND AND OBJECTIVES: Sarcopenia, defined as low muscle mass with reduced strength or function, is associated with poor outcomes in trauma patients. Head computed tomography scans routinely performed in elderly trauma patients allows for masseter sarcopenia measurement. Its association with mortality after Type II odontoid fractures has not been previously investigated. This study examines the relationship between masseter sarcopenia and mortality in elderly patients with Type II odontoid fractures. METHODS: This retrospective cohort study included patients aged 50 years or older with a Type II odontoid fracture and a head computed tomography scan within 7 days from presentation. Data collected included demographics, Charlson Comorbidity Index, treatment modality, Injury Severity Scores, Modified Frailty Index-5 (mFI-5) scores, fracture characteristics (angulation, displacement, gap, and comminution), and masseter cross-sectional area (MCSA). Sarcopenia was defined as 1 SD below sex-specific means. Multivariate Cox regressions were used to evaluate the association between MCSA and mortality, adjusting for age, sex, body mass index, Charlson Comorbidity Index, Injury Severity Scores, mFI-5, and type of treatment (operative vs conservative). Kaplan-Meier survival curves illustrated cumulative survival. RESULTS: Among 72 patients (mean age: 80.9 ± 9.5 years, 58.3% females), 14 (19.4%) had masseter sarcopenia. By 1-year postinjury, 16 (22.2%) died, increasing to 22 (30.6%) by 2 years. Masseter sarcopenia significantly predicted 1-year mortality (adjusted hazard ratio [aHR]:5.31 [95% CI: 1.44-19.62], P = .01) whereas mFI-5 predicted 2-year mortality (aHR: 1.96 [95% CI: 1.09-3.52], P = .02). By 5 years, 38 (52.8%) died, including 9 (40.9%, 95% CI: 18.6.0%-63.2%), treated operatively and 29 (58.0%, 95% CI: 43.8%-72.2%) treated conservatively ( P = .18). Among sarcopenic, 9 (64.3%, 95% CI: 35.6%-93.0%) died, compared with 29 (50.0%, 95% CI: 36.7%-63.3%) nonsarcopenic ( P = .34). Age was consistent predictor of mortality within 3 years to 5 years after injury (aHR: 1.08 [95% CI: 1.03-1.13], P < .01). CONCLUSION: Masseter sarcopenia is significantly associated with mortality within 1 year after Type II odontoid fractures in elderly patients. In this cohort, 30.6% died by 2 years and 52.8% by 5 years. Early sarcopenia identification using MCSA may aid in prognostication and postinjury management. Level of Evidence: Therapeutic Level III.