Open vs robotic-assisted pancreaticoduodenectomy, cost-effectiveness and long-term oncologic outcomes: a systematic review and meta-analysis.

BACKGROUND: Whipple pancreaticoduodenectomy (PD) is a complex gastrointestinal surgery that is performed increasingly via minimally invasive approach through robotic platforms. We sought to provide a comparative review of available data regarding robot-assisted vs open PD in terms of cost-effectiveness, overall survival, and other perioperative and long-term oncologic outcomes. METHODS: Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria, PubMed, Scopus, and Web of Science databases were searched from 1980 to April 2024 using designated keywords. English-language studies comparing costs and oncologic outcomes of robotic vs open PDs were considered for inclusion. Reviews, abstracts, case reports, letters to the editor, and non-English articles were excluded. RESULTS: A total of 1733 studies were initially identified throughout the literature search. After the removal of duplicates, title and abstract screening identified 16 studies that were included in the review. No statistically significant differences were detected in terms of short-term complications (95% CI, 0.805-1.096; P = .42), mortality (95% CI, 0.599-1.123; P = .21), and readmission (95% CI, 0.959-1.211; P = .20) among patients undergoing open vs robotic PD. Robotic PDs was associated with a slightly better overall survival (95% CI, 1.020-1.233) and higher costs (95% CI, 0.134-1.139; P = .013). Mean length of stay (LOS) was higher in the open PD group (95% CI, -0.353 to 0.189; P < .001). CONCLUSION: Robotic-assisted PD had a slightly shorter LOS and improved overall survival. There were no differences in short-term complications, mortality, or readmission. The use of cohort studies and residual potential selection bias necessitate randomized controlled trials to define the benefit of robotic PD.

Rationale and tips and tricks for transgastric robotic pancreaticogastrostomy by the double purse-string technique.

Pancreaticogastrostomy (PG) is a viable option for selected patients needing a pancreatic anastomosis. The double purse-string technique can facilitate the construction of transgastric PG but in a minimally invasive approach can lead to complications due to lack of tactile feedback. We present an adaptation of double purse-string PG for the robotic surgery, with several modifications. Firstly, the inner purse-string suture is tied through the anterior gastrotomy to improve the approximation of gastric and pancreatic serosae. Secondly, all-around-the-clock intragastric interrupted mattress sutures of e-PTFE are used to secure the pancreatic remnant to the stomach, enhancing improve hemostasis. Thirdly, e-PTFE sutures precise tension calibration due to their elastic properties and resistance to robotic manipulation. Fourthly, retroperitoneal vessels are preemptively covered by passing the pancreatic remnant through a small opening in the omentum, which is rotated upward in the omental bursa. This technique was employed in 20 PGs with no grade C postoperative pancreatic fistula. It offers a viable option robotic pancreatic anastomosis.

Instrumentless liver suspension for liver retraction in robotic pancreatoduodenectomy.

The popularity of robotic pancreatoduodenectomy (RPD) is increasing, yet it remains a complex procedure. Outcomes are influenced by various factors, including patient-specific variables, disease characteristics, and surgical technique. Numerous and intricate details contribute to the technical success of RPD. In this study, our focus is on achieving effective and "gentle" liver retraction. The use of liver retractors has been associated with the risk of retractor-related liver injury (RRLI), which can have serious consequences. Here, we introduce a refined technique for instrumentless liver retraction in RPD, developed progressively through a series of over 300 procedures. The core concept of this technique involves suspending the liver to the diaphragmatic dome. This is accomplished by securing the round ligament to the anterior abdominal wall using transparietal sutures and attaching the fundus of the gallbladder and the anterior margin of liver segment number 3 to the diaphragm. Our consecutive series of over 300 RPDs demonstrates the feasibility and safety of this approach, with no clinically relevant RRLI observed. Instrumentless liver retraction offers a valuable refinement in RPD, streamlining the procedure while reducing potential complications associated with dedicated retractors.

A comparison of pancreatojejunostomy using the modified Blumgart anastomosis with or without a four-needle three-loop suture device and continuous sutures for duct-to-mucosa anastomosis in robotic pancreaticoduodenectomy.

PURPOSE: Despite descriptions of different pancreatojejunostomy procedures using robotic pancreaticoduodenectomy (RPD), a standardized procedure has not yet been established. No prior report has described pancreatojejunostomy by RPD combined with modified Blumgart anastomosis with continuous suturing for duct-to-mucosa anastomosis. This study investigated this surgical technique and evaluated the short-term outcomes of the simplified pancreatojejunostomy procedure. METHODS: Between December 2021 and March 2024, 36 patients underwent pancreatojejunostomy using modified Blumgart anastomosis with continuous suturing for duct-to-mucosa anastomosis using RPD. Patients were divided into an early group (n = 15), without the use of the new four-needle three-loop suture device during the modified Blumgart anastomosis and a late group (n = 21) that did use this device. RESULTS: The late group had a significantly shorter pancreatojejunostomy duration (60 min vs. 49 min, p = 0.004) than the early group. Both groups showed equivalent postoperative outcomes; however, the late group exhibited a trend toward a lower rate of postoperative pancreatic fistula grade ≥ B (26.7% vs. 4.8%, p = 0.138). CONCLUSIONS: Pancreatojejunostomy using modified Blumgart anastomosis with a four-needle three-loop suture device and continuous suture for duct-to-mucosa anastomosis in patients undergoing RPD is simple and effective. This new suturing device may further reduce the incidence of postoperative pancreatic fistulas.

Learning curve of robotic pancreatoduodenectomy by a single surgeon with extensive laparoscopic pancreatoduodenectomy experience.

With the development of robotic systems, robotic pancreatoduodenectomies (RPDs) have been increasingly performed. However, the number of cases required by surgeons with extensive laparoscopic pancreatoduodenectomy (LPD) experience to overcome the learning curve of RPD remains unclear. Therefore, we aimed to analyze and explore the impact of different phases of the learning curve of RPD on perioperative outcomes. Clinical data were prospectively collected and retrospectively analyzed for 100 consecutive patients who underwent RPD performed by a single surgeon. This surgeon had previous experience with LPD, having performed 127 LPDs with low morbidity. The learning curve for RPD was analyzed using the cumulative sum (CUSUM) method based on operation time, and perioperative outcomes were compared between the learning and proficiency phases. Between April 2020 and November 2022, one hundred patients (56 men, 44 women) were included in this study. Based on the CUSUM curve of operation time, the learning curve for RPD was divided into two phases: phase I was the learning phase (cases 1-33) and phase II was the proficiency phase (cases 34-100). The operation time during the proficiency phase was significantly shorter than that during the learning phase. In the learning phase of RPD, no significant increases were observed in estimated blood loss, conversion to laparotomy, severe complications, postoperative pancreatic hemorrhage, clinical pancreatic fistula, or other perioperative complications compared to the proficiency phases of either RPD or LPD. A surgeon with extensive prior experience in LPD can safely surmount the RPD learning curve without increasing morbidity in the learning phase. The proficiency was significantly improved after accumulating experience of 33 RPD cases.

Robotic Versus Open Pancreatoduodenectomy With Vein Resection and Reconstruction: A Propensity Score-Matched Analysis.

Objective: This study aimed to compare robotic pancreatoduodenectomy with vein resection (PD-VR) based on the incidence of severe postoperative complications (SPC). Background: Robotic pancreatoduodenectomy has been gaining momentum in recent years. Vein resection is frequently required in this operation, but no study has compared robotic and open PD-VR using a matched analysis. Methods: This was an intention-to-treat study designed to demonstrate the noninferiority of robotic to open PD-VR (2011-2021) based on SPC. To achieve a power of 80% (noninferiority margin:10%; α error: 0.05; ß error: 0.20), a 1:1 propensity score-matched analysis required 35 pairs. Results: Of the 151 patients with PD-VR (open = 115, robotic = 36), 35 procedures per group were compared. Elective conversion to open surgery was required in 1 patient with robotic PD-VR (2.9%). One patient in both groups experienced partial vein thrombosis. SPC occurred in 7 (20.0%) and 6 patients (17.1%) in the robotic and open PD-VR groups, respectively (P = 0.759; OR: 1.21 [0.36-4.04]). Three patients died after robotic PD-VR (8.6%) and none died after open PD-VR (P = 0.239). Robotic PD-VR was associated with longer operative time (611.1 ± 13.9 minutes vs 529.0 ± 13.0 minutes; P < 0.0001), more type 2 vein resection (28.6% vs 5.7%; P = 0.0234) and less type 3 vein resection (31.4% vs 71.4%; P = 0.0008), longer vein occlusion time (30 [25.3-78.3] minutes vs 15 [8-19.5] minutes; P = 0.0098), less blood loss (450 [200-750] mL vs 733 [500-1070.3] mL; P = 0.0075), and fewer blood transfusions (intraoperative: 14.3% vs 48.6%; P = 0.0041) (perioperative: 14.3% vs 60.0%; P = 0.0001). Conclusions: In this study, robotic PD-VR was noninferior to open PD-VR for SPC. Robotic and open PD-VR need to be compared in randomized controlled trials.

Internal hernia through the Treitz fossa after robotic pancreatoduodenectomy: pathogenesis and preventive measures.

Internal hernia through the Treitz fossa following robotic pancreatoduodenectomy is a rare but potentially serious complication. In our review of 328 cases of robotic pancreatoduodenectomies, two patients (0.6%) required repeat surgery due to internal herniation of the entire small bowel through the Treitz fossa. This complication can present as afferent loop syndrome, with symptoms including nausea, vomiting, and abdominal distension, possibly leading to cholangitis and pancreatitis. Timely diagnosis and intervention are paramount, as conservative management often fails. Preventive measures involve closing the peritoneal defect in the Treitz fossa at the end of robotic pancreatoduodenectomy, particularly in lean patients with thin mesentery who are at increased risk of internal hernia due to increased mobility of the small bowel. This technical note elucidates the pathogenesis of Treitz hernia following robotic pancreatoduodenectomy and underscores the importance of closing the peritoneal breach to prevent this rare yet potentially serious complication.

Case Report: Robotic pylorus-preserving pancreatoduodenectomy for periampullary rhabdomyosarcoma in a 3-year-old patient.

Periampullary neoplasm is rare in pediatric patients and has constituted a strict indication for pancreatoduodenectomy (PD), which is a procedure sporadically reported in the literature among children. Robotic PD has been routinely performed for periampullary neoplasm in periampullary neoplasm, but only a few cases in pediatric patients have been reported. Here, we report the case of a 3-year-old patient with periampullary rhabdomyosarcoma treated with robotic pylorus-preserving PD and share our experience with this procedure in pediatric patients. A 3-year-old patient presented with obstructive jaundice and a mass in the pancreatic head revealed by imaging. A laparoscopic biopsy was performed. Jaundice progressed with abdominal pain and elevated alpha-amylase leading to urgent robotic exploration in which a periampullary neoplasm was revealed and pathologically diagnosed as rhabdomyosarcoma by frozen section examination. After pylorus-preserving PD, we performed a conventional jejunal loop following a child reconstruction, including an end-to-end pancreaticojejunostomy, followed by end-to-side hepaticojejunostomy and duodenojejunostomy. Delayed gastric emptying (DGE) presented with increasing drain from the nasogastric tube (NGT) a week after the surgery and improved spontaneously within 10 days. In a 13-month follow-up until the present, our case patient recovered well without potentially fatal complications, such as pancreatic fistula. Robotic PD in pediatric patients was safe and effective without intra- or postoperative complications.

Challenge in optimizing robotic pancreaticoduodenectomy including nerve plexus hanging maneuver: a Japanese single center experience of 76 cases.

BACKGROUND: Robotic pancreaticoduodenectomy (RPD) is technically demanding, and 20-50 cases are required to surpass the learning curve. This study aimed to show our experience of 76 cases from the introduction of RPD and report the changes in surgical results owing to the accumulation of cases and optimization of surgical techniques. METHODS: A total of 76 patients who underwent RPD between November 2009 and May 2023 at the Fujita Health University Hospital were divided into three groups: competency (n = 23, Nov 2009-Mar 2020), proficiency (n = 31, Apr 2020-Jun 2022), and mastery (n = 22, Jul 2022-May 2023) phases. In the mastery phase, for the education of new surgeons and maintenance of surgical quality, optimization of the procedure, including hanging maneuver with or without stapling transection of the retropancreatic tissue was implemented. The surgical outcomes were compared between the groups. RESULTS: The mean operation time decreased over time despite of the participation of newly started operators in mastery phase [competency: 921.5 min (IQR 775-996 min) vs. proficiency: 802.8 min (IQR 715-887 min) vs. mastery: 609.2 min (IQR 514-699 min), p < 0.001]. Additionally, Clavien-Dindo ≥ grade IIIa complications decreased from 52.2% in competency phase to 35.5% and 9.1% in proficiency and mastery phases, respectively (p = 0.005). CONCLUSION: Operation time and major complications decreased along the learning curve from the introduction of RPD. In addition, optimization of the procedure, including hanging maneuver of the retropancreatic tissue seemed to be effective in reducing operation time and educating new RPD surgeons.

Robotic Pancreatoduodenectomy in Portal Annular Pancreas Using a Hanging Maneuver with Indocyanine Green Fluorescence Imaging.

BACKGROUND: Sufficient knowledge and surgical management of portal annular pancreas (PAP) are essential for pancreatic surgery. As PAP is a relatively rare pancreatic anomaly, few studies have described surgical techniques for patients with PAP undergoing robotic pancreatoduodenectomy (RPD). PATIENTS AND METHODS: An 82-year-old female patient who underwent RPD presented with distal cholangiocarcinoma and type III PAP (the fusion of the uncinate process with the anteportal main pancreatic duct). After the Kocher maneuver and stomach transection, the pancreas was transected into the neck of the anteportal portion. The retroportal portion was dissected, encircled with hanging tape, and compressed. Blood supply from the mesenteric vessels was confirmed using indocyanine green (ICG) fluorescence imaging. Subsequently, the retroportal portion was stapled. CONCLUSIONS: This study demonstrates a unique surgical technique for type III PAP using the hanging maneuver with ICG fluorescence imaging. Surgeons should decide on the surgical strategy on the basis of the fusion and ductal anatomy of the pancreas.

Delayed gastric emptying after pylorus-preserving pancreatoduodenectomy: Comparison between traditional open surgery and full-robotic approach with da Vinci Xi.

INTRODUCTION: Delayed gastric emptying (DGE) is a frequent complication after pancreatoduodenectomy, especially after pylorus preservation (Pp). We evaluated the effect of a fully robotic approach with da Vinci Xi on DGE after PpPD. METHODS: Open and robotic PDs were performed in 353 and 50 cases, respectively, from January 2009 to March 2022. We compared the clinical outcomes and incidence of clinically relevant DGE between robotic PpPD (R-PpPD) and open PpPD after one-to-one case-control matching. RESULTS: Each group consisted of 30 patients. Clinically relevant DGE was less common after R-PpPD (3/30 [10%] vs. 10/30 cases [33.3%], p = 0.028). The median length of hospital stay (LoS) was significantly lower in the R-PpPD group (10 vs. 15 days, p = 0.013). CONCLUSION: The reduced tissue trauma by the minimally invasive robotic approach is associated with a lower incidence of DGE, reducing the LoS and encouraging PpPD performed using the fully robotic approach.

Right lateral approach to the superior mesenteric artery in robotic pancreaticoduodenectomy.

Ninomiya and colleagues introduced a novel approach to the superior mesenteric artery in robotic pancreaticoduodenectomy. The right lateral approach allows repositioning of the superior mesenteric artery to the right-most surface, facilitating safer artery division and simplifying detachment around the superior mesenteric vein, potentially reducing operative time and minimizing blood loss.

End-to-end invaginated pancreaticojejunostomy during minimally invasive pancreatoduodenectomy: technical description and single center experience.

BACKGROUND: Remarkable progress has been made in pancreatic surgery over the last decades with the introduction of minimally invasive techniques. Minimally invasive pancreatoduodenectomy (MIPD) remains one of the most challenging operations in abdominal surgery and it is performed in a few centers worldwide. The treatment of the pancreatic stump is a crucial step of this operation; however, the best strategy to perform pancreatic anastomosis is still debated. In this article, we describe the technical details of our original technique of modified minimally invasive end-to-end invaginated pancreaticojejunostomy (EIPJ) using video footage. METHODS: In the current study, we retrospectively analyzed a pilot series of 67 consecutive cases of minimally invasive (7 robotic/60 fully laparoscopic) MIPD operated on at the General Surgery Department of the Panico Hospital, Tricase (Italy) between March 2017 and October 2022.The reconstruction phase involved an EIPJ, tailored using an intra-ductal anastomotic plastic stent. The aim of this study was to describe the technique and evaluate the short-term outcomes of patients undergoing MIPD with EIPJ. RESULTS: The mean operative time to perform the EIPJ was 21.57 ± 3.32 min. Seven patients (10.5%) developed biochemical leaks and 13 (19.4%) developed clinically relevant pancreatic fistulas (grade B or C according to the definition of the International Study Group on Pancreatic Surgery). CONCLUSION: The early results confirm that this anastomosis is safe, easy to perform, and effective in the hands of hepatobiliopancreatic (HBP) surgeons with experience in minimally invasive surgery.

Robotic pancreas-preserving total duodenectomy: first-world experience.

Pancreas sparing total duodenectomy (PSTD) is an exceedingly rare procedure that is performed mostly for benign disease, widely involving the duodenum, that cannot be treated otherwise. PSTD requires meticulous dissection as well as reconstruction of both biliary and pancreatic drainage. Despite these technical aspects appear to be ideal for robotic assistance, robotic PSTD has not been described yet.Robotic PSTD was successfully performed in two patients. In both patients biliary and pancreatic drainage were reconstructed on the second jejunal loop, which was pulled in the duodenal bed. In the first patient, gastro-jejunostomy was performed on the blind end of the neo-duodenum (Billorth I type gastric reconstruction). In the second patient, gastro-jejunostomy was achieved in an antecolic position, 40 cm downstream the neo-ampulla in the second patient (Billorth II type gastric reconstruction). In both patients, indication to PSTD was duodenal polyps not amenable to endoscopic removal. The first patient suffered from prolonged delayed gastric emptying, but she is currently doing well 5 years and beyond after the procedure. The second patient complained of mild delayed gastric emptying that resolved spontaneously. He is now doing well 5 months after surgery.We have shown the feasibility of robotic PSTD in what we believe to be a world premiere. Further experience is required to refine the procedure and improve outcomes.

Tips and tricks for robotic pancreatoduodenectomy with superior mesenteric/portal vein resection and reconstruction.

BACKGROUND: Open pancreatoduodenectomy with vein resection (OPD-VR) is now standard of care in patients who responded to neoadjuvant therapies. Feasibility of robotic pancreatoduodenectomy (RPD) with vein resection (RPD-VR) was shown, but no study provided a detailed description of the technical challenges associated with this formidable operation. Herein, we describe the trips and tricks for technically successful RPD-VR. METHODS: The vascular techniques used in RPD-VR were borrowed from OPD-VR, as well as from our experience with robotic transplantation of both kidney and pancreas. Vein resection was classified into 4 types according to the international study group of pancreatic surgery. Each type of vein resection was described in detail and shown in a video. RESULTS: Between October 2008 and November 2021, a total of 783 pancreatoduodenectomies were performed, including 233 OPDs-VR (29.7%). RPD was performed in 256 patients (32.6%), and RPDs-VR in 36 patients (4.5% of all pancreatoduodenectomies; 15.4% of all pancreatoduodenectomies with vein resection; 14.0% of all RPDs). In RPD-VR vein resections were: 4 type 1 (11.1%), 10 type 2 (27.8%), 12 type 3 (33.3%) and 10 type 4 (27.8%). Vascular patches used in type 2 resections were made of peritoneum (n = 8), greater saphenous vein (n = 1), and deceased donor aorta (n = 1). Interposition grafts used in type 4 resections were internal left jugular vein (n = 8), venous graft from deceased donor (n = 1) and spiral saphenous vein graft (n = 1). There was one conversion to open surgery (2.8%). Ninety-day mortality was 8.3%. There was one (2.8%) partial vein thrombosis, treated with heparin infusion. CONCLUSIONS: We have reported 36 technically successful RPDs-VR. We hope that the tips and tricks provided herein can contribute to safer implementation of RPD-VR. Based on our experience, and according to data from the literature, we strongly advise that RPD-VR is performed by expert surgeons at high volume centers.

Initial 50 consecutive full-robotic pancreatoduodenectomies without conversion by a single surgeon: a learning curve analysis from a tertiary referral high-volume center.

BACKGROUND: Several studies report on a learning curve for robotic pancreatoduodenectomy (R-PD) ranging between 20 and 80 operations, with conversion rates varying between 1.1 and 35%. However, as these publications mostly refer to initial robotic experiences and do not take into account the previous surgical background in pancreatic surgery (PS) and in robotic-assisted surgery (RAS), the center's volume, as well as the platform used, we aimed to perform a surgical outcomes analysis with a particular view to these aspects. METHODS: Intraoperative and perioperative outcomes of the first 50 consecutive R-PD performed with the da Vinci Xi by the same surgeon, within a tertiary referral high-volume center, between January 2018 and March 2022, were analyzed. The surgeon was previously experienced in both PS and RAS. Shewhart control chart and cumulative sum (CUSUM) analysis were used to evaluate the learning curve of R-PD. RESULTS: All the operations were performed with a full-robotic technique, without any conversion to open surgery. Twenty of 50 patients (40%) had a BMI ≥ 25 kg/m2, while 24/50 (48%) had undergone previous abdominal surgery. Mean console time was 276.30 ± 31.16 min. The median post-operative length of hospital stay was 10 days, while 20/50 (40%) patients were discharged within post-operative day 8. Six patients (12%) had major complications (Clavien-Dindo grade 3 or above). There was no 30-day mortality. Shewhart control chart and CUSUM analysis did not show a significant learning curve during the study period. CONCLUSIONS: An extensive prior experience in both PS and RAS, within a tertiary referral high-volume center with availability of the da Vinci Xi platform, can significantly flatten the learning curve and, therefore, enable safe performance of challenging operations, i.e., pancreatoduodenectomies with a minimally invasive approach, with very low risk of conversion to open surgery, even in the first 50 operations.

Comparative analysis of opioid use between robotic and open pancreatoduodenectomy.

BACKGROUND/PURPOSE: Risk-stratified pancreatectomy clinical pathways using regional anesthesia and multimodality analgesia have decreased overall opioid use, but the additional benefits of robotic surgery in opioid reduction for pancreatoduodenectomy (PD) are unknown. We compared the inpatient opioid use between robotic PD and open PD. METHODS: Patients undergoing open PD within a protocol evaluating preincisional regional anesthetic block bundles were compared to consecutively-treated patients undergoing robotic PD identified from a prospectively maintained single-institutional database. Clinical characteristics, operative outcomes, pain scores and inpatient oral morphine equivalent (OME) use were compared between patients treated with robotic or open PD. Patients with a history of continuous-release opioid dependence were excluded. RESULTS: Of 114 total patients, 25 underwent robotic PD and 89 underwent open PD. Intraoperative opioid use was not different (P = .87), nor were cumulative pain scores. Robotic PD patients used significantly fewer OMEs per day on postoperative days 1-4 (P = .039), used fewer total OMEs during hospitalization (robotic: median = 79, IQR 42.5-141; open: median = 126, IQR 61.3-203.8; P = .0036) and were discharged with fewer OMEs (robotic: median = 0, IQR 0-43.8; open: median = 25, IQR 0-75; P = .009) despite a shorter length of stay (robotic: median = 4, open: median = 5, P = .002). CONCLUSIONS: Robotic PD patients required fewer inpatient OMEs than open PD while maintaining similar pain scores. A higher percentage of robotic PD patients tapered off of opioids prior to discharge than open surgery patients treated with a standardized opioid reduction protocol despite a shorter length of stay. These results provide a rationale for choosing robotic PD when feasible to minimize opioid use.

The standardized technique and surgical video of robotic pancreaticoduodenectomy at the Chinese PLA General Hospital.

The technical complexity of robotic pancreaticoduodenectomy (RPD) and lack of technical surgical standardization have slowed its widespread application. RPD is only routinely performed in a few highly specialized centers. This study describes in detail the standard steps and core techniques of an experienced robotic center in China. We took advantage of our single experience to provide a step-by-step technique and surgical video of our RPD standardized procedure. We divided RPD into 18 key steps. Demographics and perioperative outcomes of consecutive 20 patients who underwent the RPD standardized procedure were analyzed. For the 20 consecutive patients, the mean operative time was 253.6 min, and the median estimated blood loss was 210.0 mL. One patient required conversion to laparotomy due to the need for PV reconstruction. One patient had grade 3 complication. The median postoperative hospital stay was 11.0 days. No 90-day mortality was observed. By simplifying and optimizing the surgical techniques, the RPD procedure can be standardized and modeled to improve feasibility and repeatability.