New Penile Implants
A new innovative penile implant developed in the UK and marketed in Singapore involves the delivering of vasodilators within the corpora cavernosa by implant [Lim, 2003]. Developed by Giles R. Brindley, the device is novel in its approach as the first implanted drug delivery apparatus for the purpose of achieving an erection. The implanted device consists of two parts that are connected together: a cannula inserted into the corpora and a scrotal reservoir (Figure 7). Squeezing the scrotal pump delivers a bolus of the vasoactive drug into the confines of corpora cavernosa. One squeeze of the reservoir delivers 0.16 cc (80 mg) of sodium nitroprusside. The reservoir holds approximately 7 cc. Refilling of the reservoir can performed in an office setting by direct injection through the scrotal skin. The device has been implanted into 31 patients in the UK and Singapore; 11 implanted mechanical failures and two device infections were noted in the series. Successful usage and achievement of erection by the other participants has yet to be reported. The medicated penile implant offers a new take on implantable devices. The device is marketed to be less conspicuous than other inflatable prosthesis on the market, causes no damage to the corpora cavernosa and is cost effective. Although much more research is needed to establish efficacy of the device, there remain several questions as to the device's safety. Reservoir rupture secondary to intercourse, trauma or infection would cause release of sodium nitroprusside systemically and could be fatal. The medicated implant may provide patients with another option for erection in the near future, but further safety testing and research is required before the device may be introduced to the urologic community and considered a viable treatment alternative for ED.
Figure 7: The medicated penile implant consisting of a reservoir, device tubing and cavernosal drug delivery cannula. Source: Lim .
Another new implant is under development. This implant is based on a novel application of a nickel– titanium based shape memory alloy (SMA) that alternates between a flaccid and erect configuration with application of heat (Figure 8). The device can mimic a physiologic erection without the use of pumps or reservoirs. A recent study revealed that, compared with the AMS 700 and the Ambicor prosthesis, an SMA-based prosthesis demonstrates comparable mechanical properties. This new device is currently undergoing further refinements and it may provide urologists with a new option in penile prosthesis technology [Le et al. 2013].
Figure 8: Nickel–titanium based shape memory alloy (SMA) alternates between a flaccid and erect configuration with application of heat. Source: Le et al. .