Objective: This study was to evaluate the efficacy of three different designs of rigid fixation using polyurethane hemimandible replicas following modified sagittal split ramus osteotomy with buccal step. Materials and Methods: Forty-eight polyurethane hemimandible replicas have been used. Following the osteotomy and fixation, each specimen has been mounted on a Universal Testing unit using a prefabricated customized jig and has been tested to a range of vertical forces starting from 0 N on the incisal edge of lateral incisor and lateral forces of on lateral surface of mandibular first molar. Progressive load has been applied until a deflection of 10 mm was observed. SPSS version 20 has been used for analyzing the data. The biomechanical stability of different osteosynthesis has been compared using a one-way ANOVA with post hoc Bonferroni test. P ≤ 0.05 will be considered statistically significant. Results: After advancement of 7 mm, comparison of vertical load and lateral load among different miniplate systems showed that load was maximum in bicortical screws in inverted L pattern followed by T-shaped miniplate system and was least in single six-hole straight plate (0.001) at P ≤ 0.05. Conclusion: Our study concludes that bicortical screws in inverted “L” pattern are more resistant to lateral load as well as on the application of vertical load when compared to other fixation techniques and statistical difference was evident.