Imaging findings in the temporomandibular joint complex following radiation therapy for head and neck cancer: a review

Abstract Objectives This study aimed to identify and synthesize imaging findings in the temporomandibular joint (TMJ) complex following radiation therapy (RT) for head and neck cancer (HNC). Materials and methods A systematic search of five databases retrieved studies reporting post-RT imaging of TMJ structures. Extracted data included patient demographics, RT dose and technique, imaging modality, imaging changes and clinical findings. Risk of bias was assessed using ROBINS-I V2 (Risk of bias in non-randomized studies—of interventions, version 2). Results Eleven retrospective studies (282 patients; mean age 52.7 years; RT dose 30–110 Gy) were included. Post-RT analysis was evaluated by imaging modalities of MRI (7 studies), CT (4), US (1), and panoramic images (1). The most commonly described structural changes in the muscles of mastication included MRI signal abnormalities (43 patients), atrophy (20 patients) and hypertrophy (20 patients), while condylar changes included erosion (11 patients), surface irregularity (12 patients) or sclerosis (6 patients). Trismus was identified in 126 patients (44.7%). No study described changes to the glenoid fossa or articular eminence or direct osteoradionecrosis (ORN) of TMJ structures. All studies exhibited moderate to critical risk of bias, limiting the certainty of associations. Conclusions RT can induce structural changes across TMJ components detectable on imaging, which may contribute to trismus and functional impairment. Current evidence is limited, heterogeneous and retrospective, underscoring the need for prospective studies with standardized imaging and clinical correlation. Key Points Radiation therapy for head and neck cancer can affect jaw structures. Imaging shows changes in muscles and joints that are involved with chewing and mouth opening. These changes may lead to trismus (difficulty opening the mouth). Nearly half of patients in reviewed studies experienced this condition, impacting daily life. Current evidence is limited and inconsistent. Prospective studies with standardized imaging approaches are needed to further clarify radiation-related TMJ changes.