The researchers, from St Peter's Hospital and The Institute of Urology in London, studied 447 men who had received 504 implants over a 25-year period.

Subjects ranged from 21 to 78 with an average age of 52 and were monitored for an average of just over four years.

"Not all men are able to take medication to help them overcome erection problems" explains lead author Andrea Minervini. "Implanting a penile prosthesis remains an effective treatment, particularly for patients with medical conditions that cause irreversible erectile dysfunction.

"This large-scale study provides valuable information on more than 500 procedures, which were carried out between 1975 and 2000 by my co-authors, surgeons David Ralph and John Pryor, using ten different penile prostheses."

Key findings include:

• The most common reasons for implants were diabetes (27 per cent) and vascular disease (26 per cent). Other reasons included radical pelvic surgery and spinal cord injuries.

• Patient satisfaction rates were high. 89 per cent of the men said that they were able to have sexual intercourse and 81 per cent were satisfied with the final results of their procedure.

• 71 per cent of patients were satisfied with the actual operation. Dissatisfaction was most likely to be caused by having the prosthesis removed because of problems such as infection or mechanical failure.

• 24 per cent of the men experienced post-operative complications. Minor complications included short-term urinary retention and superficial wound infections. Major complications included prosthesis infection and mechanical failure of the device.

• Complication rates varied depending on the type of pro
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