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

It was already known that open reduction and internal fixation (ORIF) serves as the primary surgical modality for managing displaced mandibular angle fractures to restore proper occlusion and function. Surgeons typically rely on various plating systems, such as the six-hole lateral border plate, to achieve the necessary rigid immobilization of fractured segments during the essential healing phase. While the biological principles of bone healing are well-understood, the mechanical variables encountered during the actual insertion of hardware remain under-investigated in clinical settings. Previous literature has extensively debated the merits of different plating configurations and the number of screws required for stability without reaching a consensus on the role of torque. The stability of the bone-to-screw interface is paramount, as any micro-motion can lead to the infiltration of bacteria and subsequent inflammatory responses. Despite the frequency of these procedures, there is a lack of quantitative data linking the physical resistance felt during screw placement to long-term patient recovery. This absence of evidence motivated the researchers to investigate whether measuring the force of screw insertion could predict the likelihood of adverse events.

This investigation examines the specific association between the insertional torque of fixation screws and the incidence of postoperative inflammatory complications (POICs) in mandibular trauma patients. The primary objective involves determining if lower mechanical resistance during the placement of monocortical screws correlates with a higher risk of hardware failure or infection. By analyzing prospective data from a large urban academic hospital, the study seeks to provide clinicians with objective intraoperative metrics to improve surgical decision-making. The researchers focused on identifying whether the average torque across all screws or the single lowest torque value serves as a more reliable predictor of healing difficulties. This work addresses the clinical need to minimize complications such as osteomyelitis, nonunion, and fistula formation through better mechanical fixation. The study also explores how patient demographics and injury mechanisms might interact with these mechanical parameters to influence the final surgical outcome.

The research team implemented a prospective cohort study design that included all adult patients undergoing open reduction and internal fixation (ORIF) for mandibular angle fractures over a nearly three-year period. Each surgical case utilized a standardized approach involving a single six-hole lateral border plate that was secured using monocortical screws to ensure consistency across the study population. During the operative procedure, the surgeons measured and recorded the insertional torque for each of the six screws to facilitate a detailed analysis of the fixation quality. To maintain a homogenous study group, the investigators excluded patients with gunshot wounds, those requiring prolonged maxillomandibular fixation, and individuals with bilateral angle fractures. The primary outcome variable was the presence of postoperative inflammatory complications (POICs), which the authors defined as hardware infection, abscess formation, or recurrent pain and swelling. Data collection also encompassed comprehensive medical histories, injury mechanisms, and specific treatment-related variables to allow for a thorough bivariate analysis. Statistical significance was rigorously tested using a P value threshold of 0.05 to validate the relationship between torque measurements and clinical results.

The analysis revealed that the lowest insertional torque value among the six screws was significantly lower in patients who developed postoperative inflammatory complications (POICs). Specifically, the mean lowest torque for the complication group was 27.5 ± 11.0 Ncm, compared to 35.6 ± 9.7 Ncm in the group that healed without issues, resulting in a P value of 0.04. Interestingly, the average insertional screw torque across all six positions did not differ significantly between the two groups, with values of 45.0 ± 8.6 Ncm and 48.4 ± 7.6 Ncm respectively. These findings indicate that the overall stability of the plate might be compromised by a single poorly anchored screw rather than the cumulative average of the fixation. The study included 51 patients, the majority of whom were men, and observed an overall complication rate of 15.7% during the follow-up period. Other variables, including patient demographics and medical history, were evaluated but did not show the same level of predictive power as the minimum torque measurement. The data suggest that achieving a minimum threshold of resistance for every screw is a vital component of successful mandibular fracture management.

The researchers conclude that the mechanical quality of the screw-bone interface, particularly the minimum torque achieved, is a primary determinant of postoperative inflammatory complications (POICs). These results suggest that intraoperative torque measurements could serve as a valuable tool for surgeons to assess the immediate stability of their fixation. If a surgeon identifies a screw with inadequate insertional torque, they might consider alternative placement or additional stabilization to mitigate the risk of future infection or nonunion. The study highlights that the presence of even one weak point in the six-hole lateral border plate configuration can lead to adverse clinical outcomes like fistulas or hardware exposure. Future research should focus on establishing specific torque ranges that define safe versus at-risk fixation to further standardize surgical protocols. By integrating these mechanical insights into clinical practice, the medical community can work toward reducing the burden of re-operation and chronic pain for trauma patients. The authors emphasize that while the choice of plating scheme is important, the execution of the fixation at the individual screw level is equally paramount.