Longitudinal outcomes of trismus release with free-flap reconstruction in primary and secondary oral submucous fibrosis-related trismus

Background: Oral submucous fibrosis is a global health concern associated with betel quid use and results in trismus, which can be either primary or secondary in origin. Severe cases often require trismus release with free-flap reconstruction. This study examined longitudinal outcome trends following trismus release and compared the outcomes of patients with primary and secondary oral submucous fibrosis-related trismus. Methods: We conducted a retrospective cohort study by including patients who underwent trismus release between 2013 and 2022. All procedures were performed by a single surgical team to ensure technique standardisation. We measured the maximum mouth opening, the interincisal distance, perioperatively and 1, 2, 3, 4, 6 and 12 months post-operatively. Data were analysed using generalised estimating equations. Results: A total of 35 patients were included in the study, 17 with primary and 18 with secondary oral submucous fibrosis-related trismus. Initially, patients with primary oral submucous fibrosis-related trismus had greater interincisal distance gains than those with secondary oral submucous fibrosis-related trismus (p = 0.015 and p = 0.025 at 3 and 4 months post-operatively, respectively). However, after 12 months, this initial advantage faded, with comparable interincisal distance improvements in patients with primary and secondary disease, despite the more complex surgical procedures required in secondary cases. Conclusion: Surgeons should carefully consider the benefits of trismus release procedures for patients with secondary oral submucous fibrosis-related trismus by recognising the changes in post-operative outcomes.