Predictors of penile prosthesis length: results from the PHOENIX registry

Penile prosthesis implantation (PPI) is an effective treatment for refractory erectile dysfunction (ED), but changes in penile length after surgery remain a major determinant of patient satisfaction. We aimed to identify patient- and surgery-related factors associated with final penile length, measured as total implanted device length. We analysed prospectively collected data from the PHOENIX registry, a multicenter cohort including consecutive PPI cases from 29 centers between November 2021 and August 2024 (ClinicalTrials.gov NCT03849586). Baseline demographics and surgical variables were recorded. Variables significant at p < 0.05 in univariate analysis and clinically relevant covariates were entered into a multivariate linear regression model. After exclusions, 1033 patients were included (mean age 60.9 ± 9.06 years). Mean total device length was 20.0 ± 2.36 cm (range 6-28). In multivariate analysis, shorter total device length was independently associated with diabetes mellitus (adjusted coefficient -0.59 cm; 95% CI -0.97 to -0.22; p = 0.002), history of radical prostatectomy (-0.45 cm; 95% CI -1.01 to -0.11; p = 0.04), prior pelvic radiotherapy (-1.42 cm; 95% CI -2.42 to -0.51; p = 0.002), Peyronie's disease (-0.83 cm; 95% CI -1.32 to -0.34; p < 0.001), previous intracavernosal injections (-0.68 cm; 95% CI -0.99 to -0.37; p < 0.001). Avoidance of sequential corporal dilation was associated with a modest increase in device length (+0.15 cm; 95% CI 0.01 to 0.50; p = 0.04). Loss of penile length is a well-established cause of patient and partner dissatisfaction following PPI. Pre-operative counselling and management of expectations is critical to the success of the procedure. In this large prospective multicenter cohort different factors were found to be associated with greater or lesser length. Among them, and following multivariate analysis, diabetes, radical prostatectomy, radiotherapy, Peyronie's disease and prior intracavernosal injections were associated with shorter implanted device length, whereas no corporal dilation was associated with longer device length. These findings can inform preoperative counselling and surgical planning.