Moment of inertia as a means to evaluate the biomechanical impact of pelvic organ prolapse


Correspondence: Renato Natal Jorge Ph.D., Institute of Mechanical Engineering, Faculty of Engineering, University of Porto, Rua Dr Roberto Frias, Porto 4200-465, Portugal. Email:



To present an alternative measure (moment of inertia) to describe the anatomical features of the pelvic organ prolapse.


A total of 30 women (21 diagnosed as having pelvic organ prolapse and 9 as controls) were evaluated by clinical scales and magnetic resonance imaging. Imaging biometric measures were carried out. Moment of inertia, pubovisceral muscle thickness and area, and levator hiatus anterior-to-posterior and lateral measures were compared by means of non-parametric tests, as well as their correlation with demographic features of the two sample groups.


Moment of inertia, muscle area and levator hiatus diameters were statistically different between patients and controls. Furthermore, they were also well correlated with prolapse-associated factors, such as the number of vaginal deliveries and age, as well as Pelvic Organ Prolapse Quantification system and imaging staging of levator ani defects.


Moment of inertia can be used as a new parameter to evaluate pelvic floor damage resulting from prolapse.