OBJECTIVETo establish a model of individually forecasting the penile length gained after penis lengthening.

METHODSA total of 322 patients were diagnosed congenital penile shortness and received partial suspensory ligament release in our department from Oct. 1988 to Apr. 2011. The patients were divide into two groups as Modeling Group (n = 200) and Checking Group (n = 122). Then a two-dimensional model of the suspensory-ligament-release penis lengthening is established. In the Modeling Group, a statistical analysis of the penile length in flaccid and erectile state before and after penis lengthening was carried out, and a forecasting predictive function of increased penile length was derived. Then the predictive accurate rate was tested in the Checking Group.

RESULTSThere was a significant linear correlation between the increased length in flaccid and erectile state (correlation coefficient = 0.921, P < 0.01), there was also a similar relationship between the extension rate of erection before and after the operation (correlation coefficient = 0.803, P < 0.01). According to the significant linear correlations showing above, two regression forecasting models were established. A predictive function of increased flaccid length was derived from the two regression forecasting models. The effectively forecasting rates were 84.5% (169/200, the Modeling Group) and 87.7% (107/122, the Checking Group) when the absolute value of forecasting error was less than 1.5 cm.

CONCLUSIONSThe discovered significant correlation and the established forecasting function provide us a model of roughly and individually forecasting the penile length gained after penis lengthening.