Finite element analysis of the effects of individual extralevator abdominoperineal excision for rectal neoplasms below levator hiatus on pelvic floor / 天津医药

ABSTRACT

Objective To evaluate the effects of individual extralevator abdominalperineal excision (ELAPE) for rectal neoplasms below levator hiatus on pelvic floor by finite element analysis. Methods MIMICS 10.01, GeoMagic Studio 12 and ANSYS Workbench 14.0 were used to deal with magnetic resonance data of 27 healthy nulliparous volunteers'pelvic, and then three types of finite element models were developedintact models, ELAPE models and individual ELAPE models. The maximum stress in non levator ani tissue under the same load were measured in three types of models, and levator ani 's maximal stresses were measured in intact model and individual ELAPE and their stress distributions under the same pressure were analyzed and compared. Results The maximal stresses of non-levator ani tissue were (1.963±0.061) MPa, (5.127±0.070) MPa and (4.703±0.110) MPa for intact model, ELAPE model and individual ELAPE model respectively. The maximal stress was lower in individual ELAPE model than that in ELAPE model, but which was higher than that of intact model (P<0.01). The high-stress zone was found at the joints with surrounding structures on both sides of intact model and ELAPE model. The high-stress zone was found in front of the joints with surrounding structures on both sides in individual ELAPE model. The maximal stresses of three types of models were found in front of both sides. In intact model levator ani 's maximal stress was (0.812 ± 0.042) MPa, which was higher than that of individual ELAPE model (0.719 ± 0.027) MPa (P<0.01). The high-stress zone of intact model was found in front of the joints on both sides. The maximal stress was showed at ventral ends on both sides. For the individual ELAPE model the high-stress zone was found at the anterior part of the levator ani muscle and the surrounding structure. The maximum stress appeared at the top end of the left and right sides. Conclusion This individual ELAPE is able to decrease the stress of non-levator ani tissue, which suggests that the risk of postoperative pelvic floor hernia is relatively reduced.