The Association of Fracture Displacement and Surgical Intervention in Isolated Zygomatic Arch Fractures.

Background: In the evaluation of isolated zygomatic arch (ZA) fractures, a standardized guideline for recommending operative intervention is lacking.

Purpose: The study purpose was to measure the association between fracture displacement and operative treatment following isolated ZA fractures.

Study design, setting, sample: This is a retrospective cohort study identifying adult subjects with isolated ZA fractures presenting to the emergency department between September 2011 and October 2022. Subjects with non-ZA zygomaticomaxillary complex fractures or concurrent facial fractures were excluded.

Predictor/exposure/independent variable: The predictor is maximal fracture displacement in centimeters measured on axial computed tomography imaging.

Main outcome variable(s): The main outcome variable is operative management defined as recommendation of operative versus nonoperative intervention.

Covariates: Covariates collected include patient demographics; consisting of age, sex, past medical history (hypertension and diabetes); injury mechanism; social history (tobacco and alcohol use); presenting signs and symptoms (trismus, facial swelling, paresthesias, malar depression, and bony-step offs). Native overlying soft-tissue thickness was also measured on computed tomography imaging.

Analyses: Bivariate and multivariate statistical analyses were used to investigate differences between nonoperative and operative groups. Receiver operating characteristic curve was utilized to determine the discriminative fracture displacement for operative intervention. All statistical tests were performed with a significance level set at P < .05.

Results: The sample was composed of 86 subjects with an average age of 47.0 ± 19.1 years old. The mean fracture displacement was 0.29 ± 0.21 cm. Overall, 22 (25.6%) subjects were recommended operative intervention while 64 (74.4%) were managed nonoperatively. On bivariate analysis, mean fracture displacement was higher in the operative (0.51 ± 0.14 cm) versus nonoperative groups (0.21 ± 0.18 cm, P < .001). A significantly greater number of patients in the operative cohort presented with trismus, facial swelling and malar depression. Native soft-tissue thickness was not associated with operative intervention. On receiver operating characteristic curve analysis, the displacement that discriminated operative intervention was 0.36 cm with a sensitivity of 86.4% and specificity of 81.3% (area under the curve 0.9).

Conclusions and relevance: Isolated ZA fractures with a displacement of 0.36 cm or greater are associated with operative intervention. Measurement of fracture displacement may aid in clinical decision-making.