A biomechanical, histological and biochemical study in an experimental rabbit hypospadias repair model using scanning acoustic microscopy.
OBJECTIVE
To investigate the biomechanical, histological and biochemical properties of rabbit urethra at long-term follow up after hypospadias simulation and acute repair.


MATERIALS AND METHODS
Thirty-eight white New Zealand male rabbits underwent experimental creation of a hypospadias-like defect and acute repair (mobilization and advancement, tubularized incised posterior urethral plate (TIP), modified TIP) and sham operation. After 23 weeks all groups + controls underwent biomechanical, histological and biochemical assessments.


RESULTS
The mobilization and advancement group showed a higher stiffness compared to the TIP groups (P < 0.05) in the posterior urethra, whereas the TIP group was stiffer compared to the other two operative groups (P < 0.001) in the ventral urethra. In the dorsal urethra, the mobilization and advancement group and the modified TIP group had a higher collagen content compared to shams (P < 0.05). No differences in collagen content were found between groups in the ventral urethra. A correlation between acoustic and histological layers was found, partially related to collagen content.


CONCLUSION
The urethras had different microelastic properties in different layers of the dorsal and ventral urethra, with higher stiffness in the connective tissue layers surrounding and within the urethra. The repaired urethras had partially recovered their elasticity at micrometer resolution at long-term follow up. Scanning acoustic microscopy elucidated structure-function relationships at microscopic level in normal and operated urethra.