Objective To explore the effects of four extralevator abdominoperineal excision (ELAPE) procedures on the biomechanics of female pelvic floor through finite element analysis.

Methods Six finite element models of the female pelvic floor were established, including a normal model, an ELAPE model, and four individual models. The maximum stress in each model was measured under the same pressure, and the stress distribution was observed.

Results The maximum stress of non-levator ani muscle tissues on the partially reserved side and totally removed side of the levator ani muscle were 3.101±0.133 and 4.868±0.123 MPa in individual model 1, respectively, which were lower than the maximum stress in the ELAPE model (5.111±0.081 MPa; both P<0.01). The maximum stress in the non-levator ani muscle tissue were 5.138±0.091 MPa on both sides in individual model 2, which were not significantly different from that in the ELAPE model (P>0.05). The maximum stress of non-levator ani muscle tissues were 4.700±0.105 and 3.653±0.156 MPa in individual models 3 and 4, respectively, which were lower than the maximum stress in the ELAPE model (both P<0.01).

Conclusion Three ELAPE procedures, including ELAPE with unilateral levator ani muscle resection plane close to the rectum, and the bilateral pubococcygeal muscle lateral resection of levator ani muscle and levator ani muscle in front of the rectum preserved could decrease stress in the non-levator ani muscle tissue on both sides. The effect is evident on the levator ani muscle partially reserved side of ELAPE with unilateral levator ani muscle resection plane close to the rectum. ELAPE with unilateral levator ani muscle resection plane close to the pelvic wall has no significant reduction effect on the non-levator ani muscle tissue on either side.