Comparative Outcomes of Salvage Retzius-Sparing versus Standard Robotic Prostatectomy: An International, Multi-Surgeon Series.

PURPOSE: Salvage radical prostatectomy is rare due to the risk of postoperative complications. We compare salvage Retzius-sparing robotic assisted radical prostatectomy (SRS-RARP) with salvage standard robotic assisted radical prostatectomy (SS-RARP). MATERIALS AND METHODS: A total of 72 patients across 9 centers were identified (40 SRS-RARP vs 32 SS-RARP). Demographics, perioperative data, and pathological and functional outcomes were compared using Student's t-test and ANOVA. Cox proportional hazard models and Kaplan-Meier curves were constructed to assess risk of incontinence and time to continence. Linear regression models were constructed to investigate postoperative pad use and console time. RESULTS: Median followup was 23 vs 36 months for SRS-RARP vs SS-RARP. Console time and estimated blood loss favored SRS-RARP. There were no differences in complication rates or oncologic outcomes. SRS-RARP had improved continence (78.4% vs 43.8%, p <0.001 for 0-1 pad, 54.1% vs 6.3%, p <0.001 for 0 pad), lower pads per day (0.57 vs 2.03, p <0.001), and earlier return to continence (median 47 vs 180 days, p=0.008). SRS-RARP was associated with decreased incontinence defined as >0-1 pad (HR 0.28, 95% CI 0.10-0.79, p=0.016), although not when defined as >0 pad (HR 0.56, 95% CI 0.31-1.01, p=0.053). On adjusted analysis SRS-RARP was associated with decreased pads per day. Lymph node dissection and primary treatment with stereotactic body radiation therapy were associated with longer console time. CONCLUSIONS: SRS-RARP is a feasible salvage option with significantly improved urinary function outcomes. This may warrant increased utilization of SRS-RARP to manage men who fail nonsurgical primary treatment for prostate cancer.

Potential-flow models for channelled two-dimensional premixed flames around near-circular obstacles.

The dynamics of two-dimensional thin premixed flames is addressed in the framework of mathematical models where the flow field on either side of the front is piecewise incompressible and vorticity free. Flames confined in channels with asymptotically straight impenetrable walls are considered. Besides a few free propagations along straight channels, attention is focused on flames propagating against high-speed flows and positioned near a round central obstacle or near two symmetric bumps protruding inward. Combining conformal maps and Green's functions, a regularized generalization of Frankel's integro-differential equation for the instantaneous front shape in each configuration is derived and solved numerically. This produces a variety of real looking phenomena: steady fronts (symmetric or not), noise-induced subwrinkles, flashback events, and breathing fronts in pulsating flows. Perspectives and open mathematical and physical problems are finally evoked.