Biomechanical analysis of subcondylar fracture fixation using miniplates at different positions and of different lengths

Background Many types of titanium plates were used to treat subcondylar fracture clinically. However, the efficacy of fixation in different implant positions and lengths of the bone plate has not been thoroughly investigated. Therefore, the primary purpose of this study was to use finite element analysis (FEA) to analyze the biomechanical effects of subcondylar fracture fixation with miniplates at different positions and lengths so that clinicians were able to find a better strategy of fixation to improve the efficacy and outcome of treatment. Methods The CAD software was used to combine the mandible, miniplate, and screw to create seven different FEA computer models. These models with subcondylar fracture were fixed with miniplates at different positions and of different lengths. The right unilateral molar clench occlusal mode was applied. The observational indicators were the reaction force at the temporomandibular joint, von Mises stress of the mandibular bone, miniplate and screw, and the sliding distance on the oblique surface of the fracture site at the mandibular condyle. Results The results showed the efficacy of fixation was better when two miniplates were used comparing to only one miniplates. Moreover, using longer miniplates for fixation had better results than the short one. Furthermore, fixing miniplates at the posterior portion of subcondylar region would have a better fixation efficacy and less sliding distance (5.46–5.76 μm) than fixing at the anterolateral surface of subcondylar region (6.10–7.00 μm). Conclusion Miniplate fixation, which was placed closer to the posterior margin, could effectively reduce the amount of sliding distance in the fracture site, thereby achieving greater stability. Furthermore, fixation efficiency was improved when an additional miniplate was placed at the anterior margin. Our study suggested that the placement of miniplates at the posterior surface and the additional plate could effectively improve stability.

Modified Risdon approach using periangular incision in surgical treatment of subcondylar mandibular fractures

Introduction. No consensus has been reached yet on the surgical approach for treatment of condylar fractures. Objective. The aim of this study was to present modified Risdon approach (without facial nerve identification) in the treatment of subcondylar mandibular fractures. Method. This is a retrospective study of a period 2005-2012. During this seven-year period, 25 condylar mandibular fractures in 22 men and three women (19-68 years old) were treated by modified Risdon approach without identifying the facial nerve. The main inclusion criterion was subcondylar fracture according to Lindahl classification. Results. No additional morbidity related to postoperative complications, such as infection or salivary fistula, was observed in this series. Only two (8%) patients developed temporary weakness of the marginal branch of the facial nerve, which resolved six weeks postoperatively. Each patient achieved good mouth opening postoperatively. Scar was camouflaged in the first cervical wrinkle. Two patients developed temporomandibular joint dysfunction. No patient had postoperative occlusal disturbance. In all of the patients good aesthetic result was achieved in a two-year follow-up. Conclusion. In comparison with techniques described in the literature, the main advantages of the modified Risdon approach are the following: no need for facial vessels identification; direct, fast, and safe approach to mandibular angle and subcondylar region; relatively simple surgical technique and good cosmetic result - due to aesthetically placed incision. This approach could be recommended for subcondylar fracture as a simplified and safe procedure.