BackgroundPenile length (PL) shortening is an underreported phenomenon following radical prostatectomy (RP) and risk factors are not fully explored. We aimed to describe longitudinal patterns of PL recovery and evaluate factors predicting complete return to baseline PL.MethodsPL measurement was performed during a preoperative and postoperative follow-up visits at 7 days and 3, 6, 9, and 12 months. Patients who completely recovered (CR: N = 397) their preoperative stretched PL measured during at least one of their follow-up visits were compared to those with incomplete recovery (IR: N = 131). Recovery patterns were analyzed for both groups and were also compared in regards to demographics, nerve-sparing techniques, prostate size, cardiovascular risk profiles, and phosphodiesterase-5 inhibitor (PDE5i) uses. Logistic regression analyses were performed using age and other relevant clinicopathologic variables to predict PL recovery.Results60.2% of the total study population regained their preoperative PL at 12 months. Average percent (length) differences from baseline were − 1.70% (− 0.25 cm) and − 16.42% (− 2.35 cm) in the CR and the IR groups, respectively (p < 0.001). Multivariate logistic regression demonstrated that younger age (OR 0.962; 95%CI 0.931–0.994; p = 0.019), high preoperative erectile function (EF) (OR 1.028; 95%CI 1.001–1.056; p = 0.046), and consistent PDE5i use (OR 1.998; 95%CI 1.166–3.425; p = 0.012) were independent predictors of CR. At 12-month follow up, PL difference for consistent PDE5iusers was statistically different from those who did not use PDE5i consistently (− 3.25%vs. -6.64%; P = 0.001).ConclusionAge, preoperative EF, and consistent use of PDE5i were associated with complete recovery of baseline PL after RP. The therapeutic effect of PDE5i was most pronounced at 12-month visit, suggesting an added benefit with long-term use.Electronic supplementary materialThe online version of this article (10.1186/s12894-018-0341-8) contains supplementary material, which is available to authorized users.

This study is to evaluate a novel Quantum Molecular Resonance energy device as a laparoscopic bipolar vessel sealer. The majority of conventional bipolar energy-based vessel sealing devices utilize energy at frequencies between 300 kHz and 500 kHz. The use of such frequencies has disadvantages including unintended damage to surrounding tissues and excessive surgical smoke production. Here, we developed a bipolar energy source using Quantum Molecular Resonance (QMR) energy of 4–64 MHz and combined this into a laparoscopic vessel sealer. We investigate the microscopic tissue effect and surgeon’s experiences of the laparoscopic bipolar vessel sealer using a novel QMR energy source through animal experiments. QMR energy sources showed higher sealing success rates (100% vs. 66.7%) and a higher burst pressure (963 mmHg vs. 802 mmHg) of the sealed vessels compared to LigaSure™. Histological analysis showed less vessel wall injury in the QMR energy source (55.0% vs. 73.9%). In the laparoscopic setting experiments, compared to LigaSure™, QMR energy sources showed statistically significantly less smoke formation (p = 0.014), less tissue carbonization (p = 0.013), and less stickiness (p = 0.044) during sealing tissues. A novel QMR energy source for a laparoscopic bipolar vessel sealer could produce a better sealing performance and less surrounding tissue damage.