Finite element analysis of the effects of individual extralevator abdominoperineal exci-sion of rectal neoplasms in the low posterior wall on the pelvic floor / 中国肿瘤临床

ABSTRACT

Objective:To evaluate the effects of individual extralevator abdominoperineal excision (ELAPE) of rectal neoplasms in the low posterior wall on the pelvic floor by finite element analysis. Methods:MIMICS 10.01, Geo Magic Studio 12, and ANSYS Workbench 14.0 were used to analyze the magnetic resonance data obtained from the pelvic region of 27 healthy nulliparous volunteers. Three types of finite element models (intact model, ELAPE model, and individual ELAPE model) were developed. The maximal stress on non levator ani tissues were analyzed using the three models, while the maximal stress on levator ani tissues were analyzed using the in-tact model and the individual ELAPE model. Their stress distributions under the same pressure were analyzed and compared. Results:The maximal stress on non levator ani tissues obtained using the intact model, ELAPE model, and individual ELAPE model were (1.963± 0.061), (5.127 ± 0.070), and (3.667 ± 0.126) MPa, respectively, with P<0.01. High-stress zones were obtained at the joints with pelvic walls on both sides using the three models, while the maximal stresses were obtained at the joints with pubis on both sides. The maxi-mal stress on levator ani tissues obtained using the intact model and individual ELAPE model were (0.812 ± 0.042) MPa and (1.437 ± 0.043) MPa, respectively. Thus, the individual ELAPE model yielded higher values of maximal stress compared to the intact model. Both models generated high-stress zones at the joints with tendinous arch of levator ani tissues on both sides, and maximum stresses at the joints with pubis on both sides. Conclusion:Individual ELAPE decreases the stress on non levator ani tissues. This suggests that the risk of postoperative pelvic floor hernia is relatively reduced.