Selection of the corporotomy site for placement of penile implant cylinders is a matter of surgeon’s choice. Ideally the input tube should exit the corporal body where it attaches to the cylinder, avoiding any wearing of the tubing against the cylinder wall. This input tube wear was an issue 40 years ago with the single layer silicone cylinder before American Medical Systems (AMS) now Boston Scientific Corporation placed a polytetraflurethlyene (PTFE) sleave on the tubing to minimize friction. Soon after this innovation AMS introduced the triple layered cylinder, and input tube wear became a moot point with or without the PTFE sleave, as wear through three layers did not occur. I once asked a Boston Scientific executive why they maintain the PTFE sleave on the AMS 700 cylinders. He replied that the FDA, the US Food and Drug Administration, which regulates medical devices, has mandated it. I routinely strip this sleave off the tubing completely, as it is not silicone coated and can be difficult to remove during cylinder exchange due to ingrowth of body tissue into the fabric. Mentor Corporation’s (now Coloplast) cylinder is composed of bioflex, a polyurethane material, which seemed impervious to input tube wear. Today input tubing wear is not an issue with of without the PTFE sleave as both vendors cylinders seem to be resistant to this phenomenon. The other issue is the use of rear tip extenders (RTEs). I prefer to use at least a couple of RTEs in case I need to downsize the length of the cylinder. It’s more financially efficient to eliminate RTEs rather than to select a smaller cylinder. The greater the inflatable portion of the cylinder, the more the axial rigidity of the erection created. The rigidity of a three-piece inflatable cylinder however is very adequate to support the erection during intercourse even with multiple RTEs.
My choice of corporotomy location is at the penoscrotal junction where it is most easily accessible through the skin incision. At this site I can dilate proximally and distally keeping the instruments parallel to the shaft of the penis and pointing laterally to avoid tunica albuginea perforation. I extend my corporotomy proximally so that the input tube remains in the scrotum as it exits the proximal end of the corporotomy. The proximal/distal measurement ratio depends on the amount of subcutaneous fat. It’s higher in the obese patient, lower in the very thin patient. If there is redundant tubing in the scrotum, I’ll resect segments of tubing making a straight tubing connection in mid scrotum, so that the tubing from cylinders to pump is straight. If the pump is too high riding in the scrotum, I’ll splice in a piece of excess reservoir tubing making two connections on each side, so that the pump lies in the inferior portion of the scrotum.
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