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.

Sustained HCV clearance by interferon-based therapy reduces hepatocellular carcinoma in hepatitis B and C dually-infected patients.

BACKGROUND: Recent studies have indicated that interferon (IFN) or pegylated interferon (PEG-IFN) plus ribavirin therapy can achieve sustained virological response (SVR) against HCV equally in dual HBV-HCV infection and in HCV monoinfection. Whether these therapies can reduce hepatocellular carcinoma (HCC) development in dual HBV-HCV infection remains unclear. METHODS: A total of 135 dually-infected patients with active hepatitis C receiving IFN or PEG-IFN plus ribavirin therapy were enrolled. The cumulative incidence of HCC was compared to that in 1,470 HCV-monoinfected patients. RESULTS: Based on the Cox proportional hazards model, dual infection was an independent factor for HCC development in all 1,605 chronic hepatitis C patients with or without positive hepatitis B surface antigen receiving IFN or PEG-IFN plus ribavirin (hazard ratio (HR)=1.864, 95% CI 1.052-3.303; P=0.033). In dually-infected patients, HCC developed in 4 of 96 with HCV SVR and 11 of 39 without HCV SVR (P < 0.001) after a median follow-up of 4.6 years. Age (HR=1.175, 95% CI 1.070-1.291; P=0.001) and non-HCV-SVR (HR=7.874, 95% CI 2.375-26.32; P=0.001) were independent factors for HCC development. Subgroup analysis showed that HCC occurrence was lower in patients with HCV SVR and HBV DNA levels < 2,000 IU/ml at the end of treatment or follow-up compared to those with HCV SVR and HBV DNA levels ≥ 2,000 IU/ml (P=0.034) and those without HCV SVR (P<0.001). CONCLUSIONS: Sustained HCV clearance by IFN or PEG-IFN plus ribavirin therapy may significantly reduce HCC in HBV-HCV dually-infected patients, whereas persistence or reactivation of HBV decreases the benefit of HCV SVR.