Condylar remodeling after osteosynthesis of fractures of the condylar head or close to the temporomandibular joint.

ABSTRACT

PURPOSE: Condylar head fractures (CHFs) are increasingly treated by open reduction and internal fixation (ORIF). However, there are no reports on the three-dimensional postoperative volumetric transformation of the condyle, especially with regard to fragmented cases. Protruding hardware can lead to severe complications, so the goal of this study was to examine the amount of condylar bony resorption occurring after ORIF. METHODS: Included were surgically treated CHFs with eligible cone beam computer tomography (CBCT) datasets immediately after ORIF (T1) and after implant removal (T2), plus fractures of the condylar neck and base as a reference. 2D vertical and 3D volume changes of the condylar head after ORIF of CHFs were evaluated by CBCT datasets transformed into 3D models for 3D volumetric assessment using Slicer freeware. RESULTS: Among a total of 50 fractures (38 patients), including 41 CHFs (ORIF with titanium positional screws, including 15 minor and 12 major fragmented cases) plus nine extracapsular fractures (eight upper neck and one base fracture), postoperative condylar volume decreased by a mean of 0.27 cm³ (median 0.25 cm³; SD 0.23 cm³) or 16% (median 14%; SD 11%). Major fragmented CHFs showed significantly higher resorption rates (p < 0.001, range 8-42%). Age correlated with a decrease in condylar volume (mean 2.4% per 10 years of age, (p = 0.011). No significant correlation could be established between loss of condylar volume and fracture localization. A protrusion of metallic implants was seen in 20% of the assessed cases. CONCLUSION: Due to substantial volume changes of the condylar head occurring after ORIF, protrusion of implants (both metallic and resorbable) needs to be taken into consideration. An early removal of metallic ostheosyntesis material (around 4 months after ORIF) is strongly recommended to avoid adverse short- and long-term effects.