Robotic-assisted laparoscopic radical prostatectomy (RALP) has been rapidly adopted in the last few years despite having a prolonged learning curve. This article describes the RALP learning curve, reviews in detail the challenging steps of the operation, describes the authors’ RALP technique, and concludes with tips to overcome the learning curve.
For 70 years following Hugh Hampton Young’s perineal radical prostatectomy series, there were surprisingly few alterations to the surgical technique and approach. However, advances in pelvic anatomy and surgical technique to control bleeding from the dorsal venous complex (DVC) coupled with preservation of the neurovascular bundles (NVBs) decreased morbidity and led to a conversion from the perineal to the retropubic open approach. The advent of prostate-specific antigen (PSA) afforded a measure of the completeness of surgical resection and led to additional technical modifications and a drop in the acceptable postprostatectomy PSA threshold from 0.4 or less to less than 0.1. At around the same time that PSA was introduced, Schuessler and colleagues performed a series of 9 laparoscopic radical prostatectomies (LRPs) with a mean operative time of 9.4 hours, concluding that there were no advantages compared with the gold standard open radical prostatectomy (ORP). However, at the turn of the century, European urologists reported shorter operative times and consistently reproducible advantages of the laparoscopic approach, promoting acceptance of this technique.
Introduced in 1999, the da Vinci Surgical System (Intuitive Surgical Inc, CA, USA) was initially intended for cardiac surgery; however, Abbou and colleagues reported the use of the robotic platform for radical prostatectomy in a single case report with an operative time of 420 minutes. The feasibility of this new approach was also shown by Binder and Kramer in a series of 10 robotic-assisted laparoscopic radical prostatectomies (RALPs) with a 30% positive margin rate and 1 case requiring open conversion. The robotic surgical system allows for technical advantages such as three-dimensional magnified vision, enhanced ergonomics, tremor filtration, motion scaling, and improved manual dexterity, from wristed capabilities that allow for 6° of freedom of movement that overcomes some of the limited motion of pure laparoscopy. Less than a decade after its introduction, RALP was used in 75% to 85% of radical prostatectomies performed in the United States in 2008.
Although enthusiasm for this approach may be driven by good outcomes from studies from high-volume centers, 70% of all radical prostatectomies in the United States are performed by low-volume surgeons, whose findings may go unpublished. A population-based analysis of Surveillance Epidemiology and End Results (SEER)-Medicare linked data demonstrated that those undergoing LRP and RALP versus radical retropubic prostatectomy (RRP) experienced shorter hospitalizations (2 vs 3 days) and fewer heterologous transfusions (2.7% vs 20.8%) and strictures (5.8% vs 14%). These advantageous outcomes were likely driven by intrinsic qualities of the minimally invasive approach, such as small incisions with less tension on the abdominal wall, pneumoperitoneum, and superior visualization of the anastomosis. However, LRP and RALP compared with RRP were associated with more genitourinary complications (4.7% vs 2.1%) and diagnoses of incontinence (15.9% vs 12.2%) and erectile dysfunction (26.8% vs 19.2%). Subanalyses demonstrated that cystograms were obtained with 3 times greater frequency with RALP and LRP versus RRP (31.4% vs 9.9%), which may explain the higher rates of anastomotic leak diagnoses. This finding coupled with the greater risk for urinary retention from earlier attempts at catheter removal may contribute to the greater frequency of genitourinary complications observed with RALP and LRP versus RRP.
This article describes the learning curve associated with RALP, reviews in detail the challenging steps of the operation, describes the authors’ RALP technique, and concludes with tips to overcome the learning curve.
Learning curve: the challenge of radical prostatectomy
In 1936, Wright introduced the concept of a learning curve by proposing a mathematical model for the aircraft industry. Since then, it has been used to characterize the diminishing amount of time required to perform a specific repeated task. However, in the surgical field, no standard definition has been accepted, and the surgical learning curve is typically defined as the number of cases a surgeon needs to perform a particular procedure to achieve acceptable operative times and reasonable outcomes ; alternatively, it is a self-declared point at which a surgeon reaches a comfort zone when performing a procedure.
Part of the difficulty in establishing an exact definition is that individuals have different goals when performing a new procedure. Highly experienced surgeons tend to focus on different outcomes than novice surgeons, which could prolong their perception of their learning curve. Moreover, the learning curve also depends on subjective measures such as surgeon confidence, attitude, and previous experience with crossover applicability.
Population-based studies of RRP have shown that greater surgeon experience is associated with fewer perioperative complications, anastomotic strictures, and shorter lengths of stay. Hu and colleagues demonstrated that greater LRP and RALP surgeon volume was associated with fewer anastomotic strictures and better cancer control. A study of more than 7000 RRPs at 4 US centers revealed that the learning curve for biochemical recurrence plateaus at 250 cases, and the 5-year probability of recurrence was 10.7% for those treated by surgeons with 250 RRPs, but 17.9% for surgeons with fewer than 10 prior RRPs. Using a similar study design for establishing an LRP cancer control learning curve, Vickers and colleagues demonstrated that the 5-year biochemical recurrence rate for surgeons who performed 10, 250, and 750 prior LRPs were 17%, 16%, and 9%, respectively.
The learning curve for RALP is less challenging than LRP. Patel and colleagues estimated that 20 to 25 cases are required to achieve proficiency with RALP. Conversely, Herrell and Smith defined a learning curve of 150 RALPs for an experienced open surgeon to achieve similar outcomes compared with RRP and 250 RALPs to obtain surgeon comfort and confidence. For laparoscopic surgeons transitioning to RALP, Jaffe and colleagues found that the positive-margin rate for an experienced laparoscopic surgeon was 58% in the first 12 cases, decreasing to 9% after 180 cases.
At the Brigham and Women’s Hospital, a single surgeon (JCH) performed more than 700 RALPs after logging 76 RRPs during residency and 397 RALPs during fellowship training. In contrast to the studies mentioned earlier, it was found that the RALP learning curve extends beyond 250 cases, as significant improvements in estimated blood loss (EBL), operative time, and overall complications were observed throughout the first 700 cases. The EBL and operative times were 270.1 mL and 225.8 minutes, respectively during the first 100 cases, and decreased to 197.2 mL and 126.8 minutes during cases 600 to 700. The positive margin rate decreased from 17% for the first 100 cases to 12% after 400 cases, and remained constant up to 700 cases.
The rapid, widespread diffusion of the robotic technique, in conjunction with the RALP learning curve, may help explain why RRP had better outcomes in genitourinary complications, incontinence, and erectile dysfunction in a recent population-based observational cohort study using SEER-Medicare claims. Although learning curves are unavoidable for new techniques, surgeons have the responsibility to portray realistic expectations of outcomes to patients, based on their own data. A recent review of hospital Web sites showed that significant misinformation regarding RALP outcomes has been disseminated: more than 50% of the RALP Web sites had no information regarding erectile function recovery, and of those that did, 50% stated that RALP had better erectile function outcomes than RRP. Such misinformation relays unrealistic expectations, and patients striving to maintain a high level of continence and erectile function may self-select for RALP based on misleading marketing. Consequently, patients treated with RALP may have higher levels of treatment regret than those undergoing RRP. In addition, this potential selection bias may also explain the findings of increased risk of erectile dysfunction and incontinence in RALP patients.
Technical challenges of RALP
Accessing the Space of Retzius: Extraperitoneal Versus Transperitoneal Approach
RALP may be performed via an extraperitoneal or transperitoneal approach. The extraperitoneal approach was first described by Raboy and colleagues in 1997. In retrospective comparative studies, Ruiz and colleagues observed greater operative times in the transperitoneal group with similar early oncologic results for both techniques, whereas Brown and colleagues reported a slightly increased risk of ileus after the transperitoneal approach. No other significant differences between the 2 techniques have been reported.
The potential advantages of the extraperitoneal technique include: (1) confinement of potential postoperative bleeding or anastomotic leaks to the closed extraperitoneal space; (2) simulation of the RRP anatomy; (3) absence of bowel in the surgical field; (4) less need for an extreme Trendelenburg position, which improves ventilation, especially in obese patients; and (5) less risk of intra-abdominal complications such as bowel injuries.
The potential disadvantages are: (1) limited working space; (2) additional time and equipment required to create the extraperitoneal space; and (3) contraindications in patients with previous extended suprapubic laparotomy, or bilateral hernia repairs.
Bladder Neck Dissection: Standard Technique Versus Bladder Neck Preservation
Bladder neck dissection is one of the most difficult steps for newcomers to LRP and RALP. The absence of tactile sensation and unfamiliar laparoscopic anatomy may prove challenging for those inexperienced with minimally invasive approaches to radical prostatectomy, as shown by the wide variation in techniques to facilitate this step.
The standard dissection technique makes no attempt to preserve the muscle fibers of the bladder neck, which results in a larger bladder neck requiring a reconstruction before the urethrovesical anastomosis. Bladder neck preservation has been associated with several advantages, including a lower risk of bladder neck contracture, lower rates of ureteral injury, and earlier return of continence. However, others have suggested that preservation of the bladder neck compromises cancer control by increasing the risk of positive margins at the prostate base with no effect on continence.
The authors retrospectively evaluated outcomes in a series of 619 men, with 271 submitted to the standard technique and 349 submitted to bladder neck preservation. Bladder neck preservation was associated with earlier return of continence (0 pads per day) and better mean urinary function scores after 24 months of follow-up, using a self-reported validated quality-of-life instrument, the Expanded Prostate Cancer Index (EPIC) short form. Moreover, no differences were observed regarding positive margins at the prostate base.
Nerve-sparing Technique
Nerve preservation during RALP is a challenging and critical step, as it affects postoperative sexual function and cancer control. Several techniques for the release of the NVBs have been described. In an attempt to decrease the rate of positive margins, Villers and colleagues introduced the concept of the extrafascial dissection for ORP. With the improved visualization from laparoscopic approaches, new techniques of interfascial and intrafascial dissection of the NVBs have been proposed. Savera and colleagues first described the intrafascial approach, suggesting that the lateral aspect of the fascia also contains bundles of sensitive parasympathetic nerves, which are not preserved by the traditional technique. With this technique, Menon and colleagues reported a 13% positive margin rate and 100% intercourse rate in patients undergoing bilateral nerve-sparing surgery at 48 months of follow-up (with or without oral medication). Others replicated the feasibility of this technique but with less noteworthy sexual function results and a higher positive margin rate, especially for patients with pT3 disease. Curto and colleagues presented their experience with the intrafascial approach with an overall positive margin rate of 30.7% in more than 2800 procedures. Moreover, the precise role of these nerve fibers spared in the intrafascial approach but sacrificed in the interfascial approach remains unknown and warrants further study.
Regardless of the intra- versus interfascial technique used for nerve sparing, the type and amount of energy used during dissection of the neurovascular bundles is of vital importance for preservation and early recovery of sexual function. In a canine experimental model, Ong and colleagues described that the use of hemostatic energy sources such as monopolar, bipolar, or ultrasound in proximity to the NVBs is associated with the loss of erectile response to cavernous nerve stimulation acutely and after 2 weeks of follow-up.
Other sources of energy have been used in an attempt to control bleeding near the NVBs. Recently, Gianduzzo and colleagues studied the use of potassium titanyl phosphate (KTP) laser energy during nerve-sparing RRP in a canine model. They compared KTP laser with ultrasonic and athermal cold scissor dissection, and found the KTP laser provided effective hemostasis with minimum injury to the adjacent tissues, similar to the amount imparted by the athermal technique. Haber and colleagues proposed an energy-free technique with the use of a bulldog clamp and delicate sutures to control the NVBs. In this technique, a Doppler ultrasound is also used to identify the NVBs, avoiding damage to these structures. Although thermal injuries are significant, Ahlering and colleagues described the eventual recovery of sexual function after 24 months in patients submitted to use of thermal energy during NVB dissection, suggesting these injuries are reversible in the long-term.
The authors’ approach to nerve sparing has been described in detail elsewhere. In short, the authors perform a sharp athermal technique with Weck clips and cold scissors after identification of the posteromedial and anterolateral prostatic contours.
Apical Dissection
The apical dissection is one of the most crucial steps in RALP. The surgeon aims to maximize preservation of the urinary sphincter with total resection of the prostate apical tissue, targeting an optimal balance between continence and cancer control.
Different techniques have been described to minimize incontinence after radical prostatectomy. Klein refined the apical dissection technique by describing the mobilization of the distal third of the prostate with minimal damage to the external sphincter. Recently, Porpiglia and colleagues described a selective suture of the DVC for LRP. In this technique, the DVC is sectioned and a selective suture of the plexus is performed with 1 or 2 stitches, avoiding the incorporation of surrounding tissue. At 3 months, 80% of the patients who underwent selective suture ligation of the DVC were continent, compared with 53% of the patients who had surgery without selective suture ligation. Menon and colleagues described their technique of apical dissection, using an adaptation of the same technique previously described for RRP. The DVC is controlled with a single figure-of-eight stitch before it is divided down to the urethra. In their retrospective study, 96% of patients were socially dry (use of 1 pad or less per day) after 3 months of follow-up. Other intraoperative attempts to improve early continence have included the placement of the puboperiurethral stitch after the ligation of the DVC. Patel and colleagues described a suspension technique that resulted in higher continence rates at 3 months after the procedure.
The prostatic apex is generally regarded as the most common site of iatrogenic positive margins. Walsh proposed that positive apical margins commonly occur during the release of the DVC and the striated sphincter. Ahlering and colleagues showed that the use of an endovascular stapler to control the DVC decreased the positive margin rates from 27% to 5%, compared with a suture ligation technique. Guru and colleagues proposed that using cold incision of the DVC without previous suture ligation also resulted in lower apical margin rates during RALP. Men who underwent prostatectomy with cold incision apical dissection showed a positive margin rate of 2%, whereas patients with suture ligation had a positive margin rate of 8%.
Vesicourethral Anastomosis
For those early in the learning curve, the vesicourethral anastomosis may be one of the most challenging and time-consuming steps of RALP. Several techniques have been described. A single-knot continuous vesicourethral anastomosis for LRP was proposed by van Velthoven and colleagues. This technique was rapidly adopted for LRP and has been transferred to RALP. This continuous suture is fast and easy to perform, requiring just 1 knot. In a porcine model of vesicourethral anastomosis, continuous suturing was compared with an interrupted suture technique. Both techniques had similar rates of anastomotic leaks. However, histopathologic examination revealed more muscle-layer fibrosis in the group with interrupted sutures, suggesting a higher risk of anastomotic stricture.
On the other hand, the lack of haptic feedback and the potential for suboptimal suture tension after knot tying may increase the risk of anastomotic leakage. Several techniques have been described to mitigate this risk, such as the use of a Lowsley tractor and the use of an absorbable Lapra-Ty (Ethicon Inc, San Angelo, TX, USA) to keep tension and ensure an optimal posterior approximation. The authors’ technique of vesicourethral anastomosis combines the more reliable posterior approximation of the interrupted suture with the advantages of the faster running suture.
Technical challenges of RALP
Accessing the Space of Retzius: Extraperitoneal Versus Transperitoneal Approach
RALP may be performed via an extraperitoneal or transperitoneal approach. The extraperitoneal approach was first described by Raboy and colleagues in 1997. In retrospective comparative studies, Ruiz and colleagues observed greater operative times in the transperitoneal group with similar early oncologic results for both techniques, whereas Brown and colleagues reported a slightly increased risk of ileus after the transperitoneal approach. No other significant differences between the 2 techniques have been reported.
The potential advantages of the extraperitoneal technique include: (1) confinement of potential postoperative bleeding or anastomotic leaks to the closed extraperitoneal space; (2) simulation of the RRP anatomy; (3) absence of bowel in the surgical field; (4) less need for an extreme Trendelenburg position, which improves ventilation, especially in obese patients; and (5) less risk of intra-abdominal complications such as bowel injuries.
The potential disadvantages are: (1) limited working space; (2) additional time and equipment required to create the extraperitoneal space; and (3) contraindications in patients with previous extended suprapubic laparotomy, or bilateral hernia repairs.
Bladder Neck Dissection: Standard Technique Versus Bladder Neck Preservation
Bladder neck dissection is one of the most difficult steps for newcomers to LRP and RALP. The absence of tactile sensation and unfamiliar laparoscopic anatomy may prove challenging for those inexperienced with minimally invasive approaches to radical prostatectomy, as shown by the wide variation in techniques to facilitate this step.
The standard dissection technique makes no attempt to preserve the muscle fibers of the bladder neck, which results in a larger bladder neck requiring a reconstruction before the urethrovesical anastomosis. Bladder neck preservation has been associated with several advantages, including a lower risk of bladder neck contracture, lower rates of ureteral injury, and earlier return of continence. However, others have suggested that preservation of the bladder neck compromises cancer control by increasing the risk of positive margins at the prostate base with no effect on continence.
The authors retrospectively evaluated outcomes in a series of 619 men, with 271 submitted to the standard technique and 349 submitted to bladder neck preservation. Bladder neck preservation was associated with earlier return of continence (0 pads per day) and better mean urinary function scores after 24 months of follow-up, using a self-reported validated quality-of-life instrument, the Expanded Prostate Cancer Index (EPIC) short form. Moreover, no differences were observed regarding positive margins at the prostate base.
Nerve-sparing Technique
Nerve preservation during RALP is a challenging and critical step, as it affects postoperative sexual function and cancer control. Several techniques for the release of the NVBs have been described. In an attempt to decrease the rate of positive margins, Villers and colleagues introduced the concept of the extrafascial dissection for ORP. With the improved visualization from laparoscopic approaches, new techniques of interfascial and intrafascial dissection of the NVBs have been proposed. Savera and colleagues first described the intrafascial approach, suggesting that the lateral aspect of the fascia also contains bundles of sensitive parasympathetic nerves, which are not preserved by the traditional technique. With this technique, Menon and colleagues reported a 13% positive margin rate and 100% intercourse rate in patients undergoing bilateral nerve-sparing surgery at 48 months of follow-up (with or without oral medication). Others replicated the feasibility of this technique but with less noteworthy sexual function results and a higher positive margin rate, especially for patients with pT3 disease. Curto and colleagues presented their experience with the intrafascial approach with an overall positive margin rate of 30.7% in more than 2800 procedures. Moreover, the precise role of these nerve fibers spared in the intrafascial approach but sacrificed in the interfascial approach remains unknown and warrants further study.
Regardless of the intra- versus interfascial technique used for nerve sparing, the type and amount of energy used during dissection of the neurovascular bundles is of vital importance for preservation and early recovery of sexual function. In a canine experimental model, Ong and colleagues described that the use of hemostatic energy sources such as monopolar, bipolar, or ultrasound in proximity to the NVBs is associated with the loss of erectile response to cavernous nerve stimulation acutely and after 2 weeks of follow-up.
Other sources of energy have been used in an attempt to control bleeding near the NVBs. Recently, Gianduzzo and colleagues studied the use of potassium titanyl phosphate (KTP) laser energy during nerve-sparing RRP in a canine model. They compared KTP laser with ultrasonic and athermal cold scissor dissection, and found the KTP laser provided effective hemostasis with minimum injury to the adjacent tissues, similar to the amount imparted by the athermal technique. Haber and colleagues proposed an energy-free technique with the use of a bulldog clamp and delicate sutures to control the NVBs. In this technique, a Doppler ultrasound is also used to identify the NVBs, avoiding damage to these structures. Although thermal injuries are significant, Ahlering and colleagues described the eventual recovery of sexual function after 24 months in patients submitted to use of thermal energy during NVB dissection, suggesting these injuries are reversible in the long-term.
The authors’ approach to nerve sparing has been described in detail elsewhere. In short, the authors perform a sharp athermal technique with Weck clips and cold scissors after identification of the posteromedial and anterolateral prostatic contours.
Apical Dissection
The apical dissection is one of the most crucial steps in RALP. The surgeon aims to maximize preservation of the urinary sphincter with total resection of the prostate apical tissue, targeting an optimal balance between continence and cancer control.
Different techniques have been described to minimize incontinence after radical prostatectomy. Klein refined the apical dissection technique by describing the mobilization of the distal third of the prostate with minimal damage to the external sphincter. Recently, Porpiglia and colleagues described a selective suture of the DVC for LRP. In this technique, the DVC is sectioned and a selective suture of the plexus is performed with 1 or 2 stitches, avoiding the incorporation of surrounding tissue. At 3 months, 80% of the patients who underwent selective suture ligation of the DVC were continent, compared with 53% of the patients who had surgery without selective suture ligation. Menon and colleagues described their technique of apical dissection, using an adaptation of the same technique previously described for RRP. The DVC is controlled with a single figure-of-eight stitch before it is divided down to the urethra. In their retrospective study, 96% of patients were socially dry (use of 1 pad or less per day) after 3 months of follow-up. Other intraoperative attempts to improve early continence have included the placement of the puboperiurethral stitch after the ligation of the DVC. Patel and colleagues described a suspension technique that resulted in higher continence rates at 3 months after the procedure.
The prostatic apex is generally regarded as the most common site of iatrogenic positive margins. Walsh proposed that positive apical margins commonly occur during the release of the DVC and the striated sphincter. Ahlering and colleagues showed that the use of an endovascular stapler to control the DVC decreased the positive margin rates from 27% to 5%, compared with a suture ligation technique. Guru and colleagues proposed that using cold incision of the DVC without previous suture ligation also resulted in lower apical margin rates during RALP. Men who underwent prostatectomy with cold incision apical dissection showed a positive margin rate of 2%, whereas patients with suture ligation had a positive margin rate of 8%.
Vesicourethral Anastomosis
For those early in the learning curve, the vesicourethral anastomosis may be one of the most challenging and time-consuming steps of RALP. Several techniques have been described. A single-knot continuous vesicourethral anastomosis for LRP was proposed by van Velthoven and colleagues. This technique was rapidly adopted for LRP and has been transferred to RALP. This continuous suture is fast and easy to perform, requiring just 1 knot. In a porcine model of vesicourethral anastomosis, continuous suturing was compared with an interrupted suture technique. Both techniques had similar rates of anastomotic leaks. However, histopathologic examination revealed more muscle-layer fibrosis in the group with interrupted sutures, suggesting a higher risk of anastomotic stricture.
On the other hand, the lack of haptic feedback and the potential for suboptimal suture tension after knot tying may increase the risk of anastomotic leakage. Several techniques have been described to mitigate this risk, such as the use of a Lowsley tractor and the use of an absorbable Lapra-Ty (Ethicon Inc, San Angelo, TX, USA) to keep tension and ensure an optimal posterior approximation. The authors’ technique of vesicourethral anastomosis combines the more reliable posterior approximation of the interrupted suture with the advantages of the faster running suture.
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