Lower Insertional Torque of Fixation Screws for Mandibular Angle Fractures Is Associated With Complications.

Background: Open reduction and internal fixation (ORIF) is a common treatment for mandibular angle fractures. It is unknown, however, whether the insertional torque of the fixation screws is a risk factor for postoperative complications.

Purpose: The purpose of the study was to determine the association between fixation screw insertional torque and postoperative inflammatory complications (POICs).

Study Design, Setting, Sample: The authors conducted a prospective cohort study consisting of all adult patients treated with ORIF of mandibular angle fractures using a single six-hole lateral border plate secured with monocortical screws from January 1, 2020, to October 31, 2022, at a large, urban academic hospital. Patients with gunshot wounds, prolonged maxillomandibular fixation, and bilateral angle fractures were excluded.

Predictor Variable: The predictor variables were the average and lowest insertional torque of the six screws placed for fixation during ORIF.

Main Outcome Variable: The outcome variable was the presence of POICs, defined as the occurrence of exposed or infected hardware, abscess formation, recurrent swelling/pain, nonunion, osteomyelitis, or fistula formation.

Covariates: Demographics, medical history, mechanism, diagnosis, and treatment-related variables were also analyzed.

Analyses: Descriptive and bivariate analyses were performed. A P value of ≤ .05 was considered significant.

Results: There were 51 patients included in the study, 37 (72.5%) men, with a mean age of 31.2 ± 10.1 years. POICs occurred in 15.7% of patients. The average insertional screw torque was 46.9 ± 7.8 Ncm, and the mean lowest insertional screw torque per plate was 34.3 ± 10.2 Ncm. The average torque values were not lower in patients who had POICs versus those who did not (45.0 ± 8.6 Ncm vs 48.4 ± 7.6 Ncm, respectively, P = .16). However, the lowest torque value was less in patients who had POICs compared to those who did not (27.5 ± 11.0 Ncm vs 35.6 ± 9.7 Ncm, respectively, P = .04).

Conclusion And Relevance: Among patients with mandibular angle fractures treated with ORIF, decreased insertional torque for the lowest of the six screws placed for fixation was associated with complications. While previous studies have shown certain plating schemes have been associated with complications, the quality of fixation also plays a role.