Comparison of the mechanical properties of porcine buccal mucosa and ureter and the clinical implications.

Purpose: Buccal mucosal grafts have a well-established role in urology regarding the management of ureteric stricture disease. Despite its established use as a graft material there is a lack of data on the mechanical properties of buccal mucosa. We aim to compare the passive mechanical properties of porcine buccal mucosa with the ureter.

Materials and methods: Buccal mucosa (n = 20) and ureteric specimens (n = 21) were harvested from 19 domestic pigs at the time of euthanasia. Mechanical testing was performed using a uniaxial tensometer to generate stress-strain curves. From these curves, ultimate tensile strength and elastic modulus were calculated. Data was analysed, and one-way ANOVA testing was used to assess for significance variation in mechanical response due to direction of testing, and between tissue types.

Results and conclusions: Porcine ureteric specimens displayed mechanical anisotropy, with a significant difference in the elastic modulus depending on the direction of testing (p = 0.005), and a higher mean ultimate tensile strength in the longitudinal (498.09 kPa) compared to the transverse (263.99 kPa) direction (p = 0.0005). Buccal mucosa was isotropic with no significant difference in elastic modulus or ultimate tensile strength according to direction of testing. Comparison of tissue types showed a significantly greater mean ultimate tensile strength in the longitudinal direction (p = 0.002) in ureter compared to buccal mucosa. We present the first comparison of the mechanical properties of buccal mucosa with ureter, and demonstrate significant variation in elastic modulus and ultimate tensile strength between the tissue types. These findings have important clinical implications for physiological function and in the design of alternative approaches for reconstruction in buccal mucosa grafted ureters.