I came across this article talking about a new surgery technique aimed at restoring girth. Especially helpful for those suffering from hourglass deformity.
I'm not very familiar with the types of surgical procedures, maybe someone more experienced could take a look. It is somewhat recent (Nov. 2021). Don't know if it is already known here.
https://www.smoa.jsexmed.org/article/S2050-1161(21)00136-7/fulltext
Well, I guess it is aimed for penile implants only.