Association between deltoid muscle attenuation and sedation requirement in anterior shoulder dislocation

BACKGROUND: Objective radiological predictors of sedation requirement during closed reduction of anterior shoulder dislocation have not been clearly established. This study aimed to evaluate the association between humeral head displacement parameters and computed tomography (CT)-based deltoid muscle morphology and attenuation with sedation requirement. METHODS: A total of 467 patients presenting with anterior shoulder dislocation between May 2020 and February 2026 were retrospectively screened, and 213 patients were included after applying exclusion criteria. Closed reduction was performed without sedation in 182 patients and under procedural sedation in 31 patients. Humeral head displacement length, humeral head area, and the displacement length-to-head area index (HNADI) were measured on anteroposterior radiographs. CT measurements included anterior, lateral, and posterior deltoid muscle thicknesses, total cross-sectional area, and deltoid muscle attenuation (Hounsfield Units, HU). Independent predictors of sedation requirement were analyzed using multivariate logistic regression. RESULTS: Patients requiring sedation were significantly older (p=0.022), and age remained an independent predictor in multivariate analysis (OR=1.052, p=0.003). Deltoid HU was significantly higher in the sedation group (p<0.001) and independently associated with sedation requirement (OR=1.133, p<0.001). Humeral head displacement length, humeral head area, HNADI, and deltoid muscle morphometric parameters were not independently associated with sedation requirement. CONCLUSION: Sedation requirement during closed reduction of anterior shoulder dislocation is associated with advanced age and increased deltoid HU rather than bony displacement parameters. CT-based assessment of deltoid HU may have potential as an adjunctive parameter for pre-procedural sedation planning.