The first prosthesis used in 1941 was composed of vitallium (an alloy of cobalt, chromium and molybdenum).2
In 1943, testicular prostheses made of Lucite were available in a range of sizes.3
During the 1950s, numerous other materials, including glass marbles, were used.4
Gelfoam was specifically injected into the tunica albuginea following intracapsular orchidectomy performed on patients with metastatic prostate cancer.5
Plexiglass, Dacron and polyethylene prostheses have also been used without much success. It was then suggested that the ideal testicular prosthesis should be chemically inert and should not elicit any inflammatory or hypersensitivity reactions. The material should also resist mechanical strains, take and hold the desired form, be amenable to sterilisation and be a proven non-carcinogen. As a result, silastic and solid silicone rubber prostheses were developed for use in the 1960s. The demand for more natural-feeling implants led to gel-filled silicone devices appearing in 1972.6
A firmer, silicone-coated product became the standard prosthesis in 1988. However, in the US in 1992, the Food and Drug Administration (FDA) halted the use of gel-filled breast implants due to the theoretical risks of connective tissue and autoimmune disorders, the question of mechanical instability and the remote possibility of tumour development. Indeed, Robinson et al
analysed silicone breast implants removed from 300 consecutive patients and found that 64% had some form of device disruption. They suggested that most breast prostheses would lose the integrity of their silicone shell between 8–14 years after implantation. In a study of patients who had previously undergone insertion of penile prostheses, silicone particles were found in 18 of 25 operative tissue specimens and in 4 out of 4 specimens obtained from regional lymph nodes.8
This clearly demonstrated that there had been a leak of silicone into surrounding tissues from the prostheses, albeit in small amounts. This phenomenon of silicone migration is also known as gel bleed. Despite this, no subsequent evidence has been found of a link between usage of penile or testicular prostheses and connective tissue diseases.8,9
This has been further ratified by multispeciality expert panels in the US (Institute of Medicine and the National Science Panel) and the UK. The only cancers attributable to implanted silicone are seen in animal studies and are connective tissue sarcomas in susceptible strains of in-bred rodents.10
Furthermore, there was no reported increase in breast sarcomas in the US during the period of silicone breast implant use11
and there are no reported cases in the world literature of tumours arising from the usage of silicone testicular implants.
As a consequence of the concerns regarding silicone breast implants, there then followed a voluntary withdrawal of silicone-gel filled testicular prostheses in 1995 and replacement with the newly developed saline-filled prosthesis in the US (Mentor Medical Systems).
A prospective study assessing the safety profile of the Mentor saline-filled prosthesis was then undertaken by Turek et al
They studied 149 adult and paediatric patients from 18 institutions and assessed various parameters such as connective tissue disorders, complications and quality of life. At one year, none of the patients had developed connective tissue disorders and they concluded that saline-filled prostheses appeared safe and well-tolerated in the short-term.