Predisposing Conditions for Condylar Luxation After Intraoral Vertical Ramus Osteotomy 

Abstract Intraoral vertical ramus osteotomy (IVRO) is a surgical procedure for the treatment of mandibular prognathism and temporomandibular disorders. However, the improvement of temporomandibular disorders after surgery is considered to be due to the anterior and downward movement of the mandibular condyle, which may lead to condylar sag, and in the worst case, condylar luxation. In this retrospective cohort study, we examined factors potentially associated with condylar luxation. Univariate analysis indicated that condylar luxation was significantly associated with the following factors: magnitude of setback (P = 0.001); presence of temporomandibular joint (TMJ) symptoms (P = 0.002); occlusal cant correction ≥ 2 mm (P = 0.018); and mandibular condyle deformation (P < 0.001). The magnitude of setback (P = 0.035) and the presence of TMJ symptoms (P = 0.008) remained significant in the multivariate analysis. In the receiver operating characteristic curve, the cut-off value of the magnitude of setback for condylar sag and condylar luxation after IVRO was 3.25 mm. Thus, the risk of condylar luxation after IVRO is increased with a smaller magnitude of setback (≤ 3.25 mm) and the presence of TMJ symptoms. These factors should be carefully evaluated by surgeons during treatment planning for IVRO.