Understanding the mechanics of closure is key to optimal midurethral sling technique.

The animal experiments and prototype midurethral sling operations demonstrated that the sling provided new collagen to reinforce weak pubourethral ligaments (PUL). The now strengthened PULs were able to restore the contractile power of the 3 oppositely-acting directional closure forces. By contraction, these three forces exponentially altered the intraurethral resistance to flow when they closed the urethra to sustain continence. Relaxation of the forward force allowed the two posterior forces to uninhibitedly open the posterior urethral wall just prior to detrusor contraction, to facilitate evacuation of urine. The aim of this work is to examine the mechanics of the component anatomical structures which contribute to these functions, to analyse how subtle details impact on the actual surgical technique of the midurethral sling operations to optimize success, contribute to complications and how to prevent and fix them.