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Uterosacral ligaments (USLs) provide structural support to the female pelvic floor, and a loss of USL structural integrity or biomechanical function may induce pelvic organ prolapse (POP). Alterations in extracellular matrix composition and organization dictate USL mechanical function. Changes in USL microstructure and corresponding mechanical properties, however, are not fully understood, nor is it understood how microstructure and mechanics change with onset and progression of POP. This is due, in part, as USL properties are primarily characterized along a single direction (uniaxial test), whereas the USL is loaded in multiple directions simultaneously within the body. Biaxial testing permits the acquisition of biomechanical data from two axes simultaneously, and thus simulates a more physiologic assessment compared to the traditional uniaxial testing. Therefore, the objective of this study was to quantify the biaxial biomechanical properties and histological composition of the USL in post-menopausal women with and without POP at various stages. Potential correlations between tissue microstructural composition and mechanical function were also examined. Tangential modulus was lower and peak stretch higher in POP III/IV compared to non-POP and POP I/II in the main in vivo loading direction; however, no significant differences in mechanical properties were observed in the perpendicular loading direction. Collagen content positively correlated to tangential modulus in the main in vivo loading direction (r = 0.5, p = 0.02) and negatively correlated with the peak stretch in both the main in vivo (r = −0.5, p = 0.02) and perpendicular loading directions (r = −0.3, p = 0.05). However, no statistically significant differences in USL composition were observed, which may be due to the small sample size and high variability of small sections of human tissues. These results provide first step towards understanding what microstructural and mechanical changes may occur in the USL with POP onset and progression. Such information may provide important future insights into the development of new surgical reconstruction techniques and graft materials for POP treatment.

Introduction The medial thighplasty is a procedure where patients may attain superior mobility, hygiene, and cosmesis. Most surgeons use attachment of the superficial fascial system (SFS) of the thigh flap to the Colles fascia, whereas others attach the SFS to the pubic ramus periosteum. Because of a high complication profile, we aim to elucidate the clinical, biomechanical, and anatomic qualities of the Colles fascia versus the pubic ramus periosteum. Materials and methods We performed a 17-year retrospective review documenting clinical complications, a biomechanical analysis of sutures placed in different tissue layers of the thigh, and a histologic analysis surrounding the ischiopubic ramus. Separate suture pull-out strength testing was conducted on cadaveric tissue using an Admet MTEST Quattro with no. 1 Vicryl suture and tissue grips at a displacement rate of 2.12 mm/s. Simultaneous displacement and force were acquired at 100 Hz and with measurements obtained at regular intervals between the pubic symphysis and the ischial tuberosity in both the Colles fascia and the deeper periosteal layers of the thigh. A histologic analysis was performed at 3 points along the ischiopubic ramus using paraffin-embedded large mount tissue sections stained with hematoxylin, eosin, and Gomori trichrome. Results Thirty-nine patients underwent medial thighplasty with a 46.16% complication rate. Suture pull-out force of the suspected superficial Colles fascia sites was, on average, 72.8% less than values from the deeper periosteum tissue. Anchor points in the Colles fascia elongated 17.4% further before failure than those in the periosteum. There was noticeable variability between anchor points and across samples. The histologic sections suggest that the Colles fascia from the different regions of the ischiopubic ramus varies considerably in both continuity and collagen fiber content with no discernible pattern. The periosteal and muscular fascial layers were more continuous histologically with direct attachments into the pubis and ischium. Conclusions Anchoring of the SFS to the periosteum did not improve our complication profile when compared with the literature. Both the biomechanical and histologic analyses demonstrate that the Colles fascia is highly variable in organizations with coincident variability in tissue strength. Our results require further study to identify the optimal surgical technique for medial thighplasty.

DISCLOSURE/FINANCIAL SUPPORT: None of the authors has a financial interest in any of the products, devices, or techniques mentioned in this manuscript.