Impact of key pinch strength on patient preference for inflatable penile prosthesis: a prospective study comparing Coloplast™ and AMS™ models

Our purpose was to determine if key pinch strength is predictive of patient preference for a single IPP model among three currently available models (Coloplast™ Titan, Coloplast™ Titan Touch, and the Boston Scientific AMS 700™). We prospectively recruited men without penile prostheses over 65 years old from our urology clinic. Demographic and medical history were recorded. To measure key pinch strength study participants squeezed a dynamometer between their thumb and index finger while seated with their arm resting at 90°; the strongest of three attempts was recorded. Participants were asked to operate three inflatable penile prosthesis devices installed within identical penis models. The number of pumps required to achieve erection with each device was recorded. Participants were asked to rate difficulty of inflation on a 1–5 scale. Participants ranked, from best to worst, which device they preferred based on ease of inflation. A total of 100 men completed the study. Median age and key pinch strength were 70.0 years and 19.0 pounds. Coloplast Titan was the most favored pump based on ease of inflation (58%). The median age, median key pinch strength, and median number of pumps required for erection were similar among men that favored Coloplast Titan as compared with AMS 700 and Coloplast Titan Touch. Multivariate linear regression of the 1–5 rating scale revealed lower grip strength to be associated with increased difficulty of inflation of Coloplast Titan Touch (p  = 0.045). No other factors were associated with increased difficulty of inflation. Men with below-average key pinch strength may benefit from being offered a model other than Coloplast Titan Touch. Whether these findings translate to men who have already received implants remains to be determined. Nevertheless, evaluation of pinch strength should be considered in men prior to implantation of IPP.