Aging-related morphological changes in the obturator internus and levator ani

Background Pelvic floor dysfunction is a common condition in adult women that substantially impacts their quality of life. Most studies have focused on the levator ani muscle, but recent anatomical insights suggest that the surrounding muscles, such as the obturator internus, also play a key structural role. However, the age-related morphological changes in these muscles remain poorly understood. Objective To quantitatively characterize age-related morphological changes in the obturator internus and levator ani muscles using geometric morphometric techniques. Study Design: This cross-sectional study included 27 adult women aged 25–83 years with gynecological conditions but without pelvic floor disorders, as evidenced by clinical or imaging parameters. Standardized pelvic magnetic resonance imaging scans were obtained between April 2024 and July 2024 at a single tertiary care center. Elliptic Fourier analysis was applied to the segmented contours of the obturator internus, and a landmark-based method was used to evaluate the combined shape of the obturator internus and levator ani. Principal component analysis and linear regression were performed to assess the associations with age. Procrustes analysis of variance was used to evaluate the overall shape-age relationships. Results Elliptic Fourier analysis revealed that increasing age was significantly associated with decreased thickness, downward displacement of the medial surface groove, and eminence of the obturator internus (p = .008, R² = .25). Landmark-based analysis revealed similar age-related shape changes, including inferior displacement of the groove, verticalization of the levator ani, and widening of the levator hiatus (p = .001, R² = .343). Procrustes analysis revealed a significant relationship between age and overall shape variation (p = .003). Conclusions Aging was associated with coordinated structural remodeling of the obturator internus and levator ani. These findings suggested that, in addition to traditional pelvic floor–focused approaches, strategies targeting hip joint function may offer novel opportunities for the assessment and rehabilitation of patients with pelvic floor dysfunction.