When there is lack of efficacy or dissatisfaction with other modalities, penile prostheses are often the best alternative for erectile dysfunction. Unlike the other modalities, prosthesis surgery is irreversible in that the corporal tissue is permanently altered such that physiologic erections are no longer possible. If the prosthesis has to be removed, there will be complete ED, although devices are readily replaced should mechanical failure occur. While a variety of exotic materials, flaps , and grafts have been used, most contemporary prostheses are hydraulic or semi-rigid/malleable. The malleable prostheses are made of silicone rubber with a central intertwined metallic core. Mechanical devices are also made of silicone rubber with interlocking segments in a column, which provide rigidity when the rings are lined up in a straight line and flaccidity when the penis is bent (similar to a gooseneck lamp). The advantages of semi-rigid devices are that they are easy to implant, have few mechanical parts with minimal mechanical failure, and generally last longer than inflatable devices. The major disadvantage of the semi-rigid devices is that the penis is neither fully rigid nor fully flaccid. These devices may interfere with urination, are difficult to conceal, and have a higher likelihood of device erosion. About 15% of patients choose semi-rigid rod implants, and those with limited mental or manual dexterity are encouraged to have this type of device.

Currently available inflatable prostheses come in two or three-component setups. Two-piece inflatable prostheses consist of a pair of cylinders attached to a scrotal pump. The prosthesis can be deflated by bending the penis at midshaft. Finally, three-piece inflatable prostheses consist of a pair of penile cylinders, a scrotal pump, and a supra-pubic reservoir. They provide excellent rigidity when erect and a more natural appearance when flaccid. When fully erect, they are as rigid as the two-piece device. In the flaccid state, they surpass flaccidity of two-piece prostheses. Of all the prosthesis types, hydraulic three-piece implants have been the most popular, accounting for 85% of the US market. Most inflatable devices will need replacement after 10-15 years. Repair or replacement rates of 5%-20% in the first five years are realistic.

Of all modalities for management of ED, prostheses have the highest satisfaction rates , with 2 large studies demonstrating greater than 95% satisfaction . This extremely high satisfaction rate is like due to multiple factors: prostheses allow for spontaneous and repeated reliable erections without external medications or devices. Also, many men undergoing prostheses have tried, unsuccessfully or unsatisfactorily, many 1st and 2nd line treatments prior to deciding on a prosthesis.

Infection remains the most devastating and feared complication. Modern prostheses allow for antibiotic impregnation and elution, and infection rates are approximately 3% for a first-time prosthesis. Although some studies suggest that elevated HbA1c levels may predict a higher rate of infections in diabetics having penile prosthesis surgery, more recent studies refute this. A large study from Wilson, et al demonstrated that neither diabetic status nor preoperative HgA1c were risk factors for prosthesis infection. A more recent study also finds that elevated HbA1c is not a risk factor for infection but notes that short-term sugar control is (as defined by morning fasting glucose levels >200 ng/ml), although data is hampered by very low numbers of patients within that cohort. Penile shortening and eventual mechanical failure of the device are other common side effects.