Patterns of Postoperative Trismus Following Mandibulectomy and Fibula Free Flap Reconstruction

SIMPLE SUMMARY: Trismus is a serious sequela of head and neck cancer (HNC) treatment that can profoundly affect quality of life. While the relationship between radiotherapy and trismus in HNC has been established, the surgical risk factors for trismus in HNC patients are largely unclear. This study reports the prevalence of postoperative trismus in a large cohort of patients who underwent mandibulectomy and fibula free flap reconstruction. Patients with a posterior mandibulotomy that involved or removed the ramus had significantly higher rates of persistent trismus >6 months after surgery, which was also demonstrated in a multivariable logistic regression. These findings may inform future surgical planning and potentially optimize functional outcomes in patients undergoing significant mandibular resection. ABSTRACT: The factors that contribute to postoperative trismus after mandibulectomy and fibula free flap reconstruction (FFFR) are undefined. We retrospectively assessed postoperative trismus (defined as a maximum interincisal opening ≤35 mm) in 106 patients undergoing mandibulectomy with FFFR, employing logistic regression to identify risk factors associated with this sequela. The surgical indication was primary ablation in 64%, salvage for recurrence in 24%, and osteonecrosis in 12%. Forty-five percent of patients had existing preoperative trismus, and 58% of patients received adjuvant radiation/chemoradiation following surgery. The overall rates of postoperative trismus were 76% in the early postoperative period (≤3 months after surgery) and 67% in the late postoperative period (>6 months after surgery). Late postoperative trismus occurred more frequently in patients with ramus-involving vs. ramus-preserving posterior mandibulotomies (82% vs. 46%, p = 0.004). A ramus-involving mandibulotomy was the only variable significantly associated with trismus >6 months postoperatively on multivariable logistic regression (OR, 7.94; 95% CI, 1.85–33.97; p = 0.005). This work demonstrates that trismus is common after mandibulectomy and FFFR, and suggests that posterior mandibulotomies that involve or remove the ramus may predispose to a higher risk of persistent postoperative trismus.