There are many different testicular implants produced throughout the world but generally they come in two varieties: a solid ovoid block of silicone or a silicone shell filled with saline. In the United States, however, there is only one FDA approved prosthesis available, the Torosa prosthesis made by Coloplast. This is testicular prosthesis that we use during a metoidioplasty.
The Torosa testicular prosthesis comes in a variety sizes and is filled with saline. The amount of saline filled during surgery can change the feel of the prosthesis and give more or less density to the prosthesis.
Typically for transmen undergoing metoidioplasty, the testicular prosthesis will be placed at the same time rather than as a separate surgical procedure.
While some patients want as large a prosthesis as possible, there is a balance between the size of the new phallus and the prosthesis. If the testicular prosthesis is too big, the phallus will appear buried and not protrude out through the body.
I typically make a slightly curved incision on each side above where the prosthesis will go – an alternative is to make an incision medially where the urethra is being reconstructed and place the prosthesis through this so there is fewer incisions. With the second way there is less scar but, in my opinion, a somewhat higher risk of erosion and infection of the prosthesis after the metoidioplasty.
After surgery a capsule forms around the prosthesis to keep it in place. This process takes a few weeks to occur – during this time we ask metoidioplasty patients to confirm that the prosthesis is kept down in the scrotal sac periodically. Also, metoidioplasty patients are asked to walk in with their legs slightly spread apart because the thighs can push the prosthesis up and migrate higher and into the inguinal area. If the capsule forms around the testes when they are higher in the scrotum than it will become permanently more mobile and periodically migrate higher into the inguinal area. If this does happen then you might need a minor surgery to correct this and remove the excess capsule and bring the prosthesis down into the proper position.
Other potential complications include infection or erosion of the testicular prosthesis which mandates removal of the testicular prosthesis and potentially replacing during a later surgery. Sometimes, patients can have minor pain or bleeding around the site of prosthesis.
Overall, though, most transmen are very satisfied with appearance and feel of the testicular prosthesis after metoidioplasty.