Though he was aware of Frederick's homosexual reputation, Frederick's physician Johann Georg Ritter von Zimmermann denied that Frederick was homosexual. Zimmermann claimed that Frederick had convinced himself that he was impotent due a minor deformity Frederick had received during an operation to cure gonorrhea in 1733. According to Zimmermann, Frederick pretended to be homosexual in order to appear that he was still virile and capable of intercourse, albeit with men. This story is doubted by Wolfgang Burgdorf, who is of the opinion that "Frederick had a physical disgust of women" and therefore "was unable to sleep with them". The surgeon Gottlieb Engel, who prepared Frederick's body for burial, indignantly contested Zimmerman's story, saying the king's genitalia was "complete and perfect as those of any healthy man".