Temporomandibular joint degenerative changes following mandibular fracture: a computed tomography-based study on the role of condylar involvement

This study assessed the incidence of postfracture radiological temporomandibular joint (TMJ) degeneration in patients with different types of mandibular fractures, focusing on the impact of condylar fractures.

This retrospective review included patients diagnosed as having mandibular fractures from 2016 to 2020 who had undergone initial computed tomography (CT) and a follow-up CT scan at least 1-month postfracture. Patient demographics, fracture details, treatment methods, and radiological signs of TMJ degeneration on CT were analyzed to identify risk factors for postfracture TMJ degeneration, with a focus on condylar head fracture and non-head (condylar neck or base) fractures.

The study included 85 patients (mean age: 38.95 ± 17.64 years). The per-patient analysis indicated that the incidence of new radiologic TMJ degeneration on CT was significantly the highest (p < 0.001) in patients with condylar head fractures (90.91%), followed by those with non-head condylar fractures (57.14%), and those without condylar involvement (24.49%). The per-joint analysis indicated nearly inevitable degeneration (93.94%) in 33 TMJs with ipsilateral condylar head fractures. For the remaining 137 TMJs, multivariate logistic regression revealed that other patterns (ipsilateral non-head, contralateral, or both) of condylar fractures (odds ratio (OR) = 3.811, p = 0.007) and the need for open reduction and internal fixation (OR = 5.804, p = 0.005) significantly increased the risk of TMJ degeneration.

Ipsilateral non-head condylar fractures and contralateral condylar fractures are associated with a high risk of postfracture TMJ degeneration. Indirect trauma plays a vital role in postfracture TMJ degeneration.