The Stability Evaluation of Two Internal Fixation Patterns of Extracapsular Condylar Fracture Based on One Novel Measuring Method.

PURPOSE The most stable internal fixation pattern for extracapsular condylar fracture (ECF) has been controversial. In this study we aimed to evaluate the stability of 2 common internal fixation patterns using 1 or 2 miniplates separately. One novel measuring method based on the angle of miniplates' localization was introduced. MATERIALS AND METHODS Twenty-seven patients with 30 sides of extracapsular condylar fracture were enrolled in this retrospective study. All cases were performed open reduction and internal fixation using 1 or 2 titanium plates with both the postoperative immediate CT (T1) and the over 6 months' follow-up CT (T2). Mandibles and implants were segmented and reconstructed respectively using SIMPANT 14.04 software. For 1 miniplate group, the sagittal crossing angle (<1) between miniplate (P1) and posterior border of ipsilateral ramus was measured. For 2 miniplates group, the sagittal crossing angle (<2) between 2 miniplates (P2a, P2b) was measured. Both anteroposterior (∠AP) and mediolateral angle change (∠ML) of each miniplate between T1 and T2 was measured. The stability of 2 internal fixation patterns was measured and evaluated based on the angle change of miniplates. And also the stability of each internal fixation pattern could be investigated based on the relationship between the placement patterns of miniplates and the angle change. RESULTS Fifty-two miniplates were finally segmented and reconstructed successfully, including 8 of 1 miniplate group and 44 of 2 miniplate group. For 1 miniplate group, the average ∠AP and ∠ML were 6.10° and 8.54°, respectively. For 2 miniplate group, the average ∠AP and ∠ML of P2a were 3.02° and 2.56°, respectively, as well as 3.12° and 3.07° of P2b. CONCLUSIONS The novel measuring method based on the angle of miniplates' localization showed potential for the stability evaluation of internal fixation of condylar fracture. In summary, the internal fixation patterns using 2 miniplates shows better stability than that of 1 miniplate.