Characteristics of subscapularis muscle strain in professional baseball players: a case series.

BACKGROUND: Subscapularis muscle strains can develop in professional baseball players, rendering the players unable to continue playing for a certain period. However, the characteristics of this injury are not well known. The purpose of the present study was to investigate the details of the injury and the postinjury course of subscapularis muscle strain in professional baseball players. METHODS: Of 191 players (83 fielders and 108 pitchers) who were members of a single Japanese professional baseball team between January 2013 and December 2022, 8 players (4.2%) had subscapularis muscle strain and were enrolled in this study. The diagnosis of muscle strain was made on the basis of shoulder pain and magnetic resonance imaging findings. The incidence of subscapularis muscle strain, the details of the site of the injury, and the time to return to play were examined. RESULTS: Subscapularis muscle strain occurred in 3 (3.6%) of 83 fielders and 5 (4.6%) of 108 pitchers, with no significant difference between fielders and pitchers. All players had injuries on the dominant side. Most injuries were located at the myotendinous junction and in the inferior half of the subscapularis muscle. The mean time to return to play was 55.3 ± 40.0 (range, 7-120) days. At a mean 22.7 months after the injury, there were no reinjured players. CONCLUSION: A subscapularis muscle strain is a rare injury among baseball players, but in players whose shoulder pain cannot be given a definite diagnosis, subscapularis muscle strain should be considered as a possible etiology.

Safety of laparoscopic liver resection for high-risk patients.

BACKGROUND/PURPOSE: To investigate the safety of laparoscopic liver resections (LLRs) for high-risk patients (HRs) with preoperative comorbidities affecting the heart, lungs, kidneys, glucose tolerance, and central nervous system. METHODS: This retrospective study included 585 patients who had undergone total hepatectomies from 2006 to 2020. Among them, 239 patients underwent LLRs, and 349 underwent open liver resections (OLRs). The safety and validity of LLRs were analyzed by comparing outcomes and preoperative records between HRs and nonhigh-risk patients (nHRs). HRs were defined as patients with any type of chronic heart disease rated New York Heart Association II or higher, chronic obstructive pulmonary disease rated stage III or higher, chronic kidney disease rated stage III or higher, insulin-dependent diabetes mellitus, or cerebrovascular disease with neurological sequelae. RESULTS: A total of 117 LLRs (49.0%) were performed in HRs, and there were more patients with ASA class III or higher than nHRs. Complications of Clavien-Dindo classification grade 3b or higher were not observed in HRs and in only one nHR. Furthermore, no postoperative exacerbations of the five HRs factors were observed in either group. CONCLUSIONS: Rigorous assessment of surgical indications and perioperative management can promote safe LLRs, even in HRs with comorbidities.

The Outcome of Conversion to Hand-Assisted Laparoscopic Surgery in Laparoscopic Liver Resection.

BACKGROUND: Hand-assisted laparoscopic surgery (HALS) is known as a useful option. However, the outcome and predictor of conversion to HALS in laparoscopic liver resection (LLR) are unclear. METHODS: Data from consecutive patients who planned pure LLR between 2011 and 2020 were retrospectively reviewed. Univariate and multivariate analyses were performed and compared pure LLR, HALS, and converted open liver resection (OLR). RESULTS: Among the 169 LLRs, conversion to HALS was performed in 19 (11.2%) and conversion to OLR in 16 (9.5%). The most frequent reasons for conversion to HALS were failure to progress (11 cases). Subsequently, bleeding (3 cases), severe adhesion (2 cases), and oncological factors (2 cases) were the reasons. In the multivariable analysis, the tumor located in segments 7 or 8 (p = 0.002) was evaluated as a predictor of conversion to HALS. Pure LLR and HALS were associated with less blood loss than conversion to OLR (p = 0.005 and p = 0.014, respectively). However, there was no significant difference in operation time, hospital stay, or severe complications. CONCLUSIONS: The predictor of conversion to HALS was a tumor located in segments 7 or 8. The outcome of conversion to HALS was not inferior to pure LLR in terms of bleeding, operation time, hospital stay, or severe complication.

Improvement of Coxarthrosis Due to Realignment of Pelvic Retroversion Following Spinal Corrective Surgery: A Case Report.

CASE: A 70-year-old woman presented with severe trunk deformity, gait disturbance, and bilateral hip pain. Radiography and magnetic resonance imaging revealed severe spinal kyphosis, bilateral osteoarthritis of the hip joints, and lumbar canal stenosis. A 2-stage corrective surgery for the treatment of spinal kyphosis was performed. Subsequently, the spinopelvic alignment changed remarkably. The spinal symptoms and radiographic parameters improved postoperatively, and bilateral hip pain and range of motion also showed improvement. CONCLUSION: Corrective surgery for the treatment of degenerative spinal kyphosis affected the spinopelvic alignment, and the symptoms of simultaneous coxarthrosis also improved after the corrective surgery.

An International Retrospective Observational Study of Liver Functional Deterioration after Repeat Liver Resection for Patients with Hepatocellular Carcinoma.

Whether albumin and bilirubin levels, platelet counts, ALBI, and ALPlat scores could be useful for the assessment of permanent liver functional deterioration after repeat liver resection was examined, and the deterioration after laparoscopic procedure was evaluated. For 657 patients with liver resection of segment or less in whom results of plasma albumin and bilirubin levels and platelet counts before and 3 months after surgery could be retrieved, liver functional indicators were compared before and after surgery. There were 268 patients who underwent open repeat after previous open liver resection, and 224 patients who underwent laparoscopic repeat after laparoscopic liver resection. The background factors, liver functional indicators before and after surgery and their changes were compared between both groups. Plasma levels of albumin (p = 0.006) and total bilirubin (p = 0.01) were decreased, and ALBI score (p = 0.001) indicated worse liver function after surgery. Laparoscopic group had poorer preoperative performance status and liver function. Changes of liver functional values before and after surgery and overall survivals were similar between laparoscopic and open groups. Plasma levels of albumin and bilirubin and ALBI score could be the indicators for permanent liver functional deterioration after liver resection. Laparoscopic group with poorer conditions showed the similar deterioration of liver function and overall survivals to open group.

Characteristics of internal oblique muscle strain in professional baseball players: a case series.

BACKGROUND: Internal oblique muscle strains can develop in professional baseball players, rendering the players unable to continue playing for a certain period. However, the characteristics of this injury are not well known. The purpose of the present study was to investigate the details of the injury and the post injury course of internal oblique muscle strain in professional baseball players. METHODS: The subjects were members of a single Japanese professional baseball team with a total of 188 players (81 fielders and 107 pitchers) who developed internal oblique muscle strains from January 2012 to December 2021. The diagnosis of muscle strain was made on the basis of local pain and magnetic resonance imaging findings. The incidence of internal oblique muscle strain, the details of the site of the injury, and the time to return to play were examined. RESULTS: There were 28 cases in 23 players (12.2%) of internal oblique muscle strain. The players were 16 fielders (24.7%) and 7 pitchers (7.5%), with a significantly greater incidence in fielders (p = 0.001). Although internal oblique muscle strain was more common on the side contralateral to the batting or pitching side, it occurred on either side. Most of the injury sites were at the region of the muscle insertion to the lower ribs. At a mean time of 36.5 months after the initial injury, 5 players (21.7%) developed another internal oblique muscle strain. The mean time to return to play was 27.7 ± 9.7 days (range, 4-53 days). CONCLUSIONS: Baseball players who have symptoms at the side of the trunk should be regarded as having possible internal oblique muscle strain, and proactive examination should be considered.

Predictors of a difficult Pringle maneuver in laparoscopic liver resection and evaluation of alternative procedures to assist bleeding control.

PURPOSE: To evaluate the predictors of a difficult Pringle maneuver (PM) in laparoscopic liver resection (LLR) and to assess alternative procedures to PM. METHODS: Data from patients undergoing LLR between 2013 and 2020 were reviewed retrospectively. Univariate and multivariate analyses were performed and the outcomes of patients who underwent PM or alternative procedures were compared. RESULTS: Among 106 patients who underwent LLR, PM could not be performed in 18 (17.0%) because of abdominal adhesions in 14 (77.8%) and/or collateral flow around the hepatoduodenal ligament in 5 (27.8%). Multivariate analysis revealed that Child-Pugh classification B (p = 0.034) and previous liver resection (p < 0.001) were independently associated with difficulty in performing PM in LLR. We evaluated pre-coagulation of liver tissue using microwave tissue coagulators, saline irrigation monopolar, clamping of the hepatoduodenal ligament using an intestinal clip, and hand-assisted laparoscopic surgery as alternatives procedures to PM. There were no significant differences in blood loss (p = 0.391) or transfusion (p = 0.518) between the PM and alternative procedures. CONCLUSIONS: Child-Pugh classification B and previous liver resection were identified as predictors of a difficult PM in LLR. The alternative procedures were found to be effective.

Landmarks and techniques to perform minimally invasive liver surgery: A systematic review with a focus on hepatic outflow.

PURPOSE: In this systematic review, we aimed to clarify the useful anatomic structures and assess available surgical techniques and strategies required to safely perform minimally invasive anatomic liver resection (MIALR), with a particular focus on the hepatic veins (HVs). METHODS: A systematic review was conducted using MEDLINE/PubMed for English articles and Ichushi databases for Japanese articles through September 2020. The quality assessment of the articles was performed in accordance with the Scottish Intercollegiate Guidelines Network (SIGN). RESULTS: A total of 3372 studies were obtained, and 59 were selected and reviewed. Due to the limited number of published comparative studies and case series, the degree of evidence from our review was low. Thirty-two articles examined the anatomic landmarks and crucial structures for approaching HVs. Regarding the direction of HV exposure, 32 articles focused on the techniques and advantages of exposing HVs from either the root or the periphery. Ten articles focused on the techniques to perform a segmentectomy 8 in particularly difficult cases of MIALR. In seven articles, bleeding control from HVs was also discussed. CONCLUSIONS: This review may help experts reach a consensus regarding the best approach to the management of hepatic veins during MIALR.

Expert Consensus Guidelines: How to safely perform minimally invasive anatomic liver resection.

BACKGROUND: The concept of minimally invasive anatomic liver resection (MIALR) is gaining popularity. However, specific technical skills need to be acquired to safely perform MIALR. The "Expert Consensus Meeting: Precision Anatomy for Minimally Invasive HBP Surgery (PAM-HBP Surgery Consensus)" was developed as a special program during the 32nd meeting of the Japanese Society of Hepato-Biliary-Pancreatic Surgery (JSHBPS). METHODS: Thirty-four international experts gathered online for the consensus. A Research Committee performed a comprehensive literature review, classifying studies according to the Scottish Intercollegiate Guidelines Network method. Based on the literature review and experts' opinions, tentative recommendations were drafted and circulated among experts using online Delphi Rounds. Finally, formulated recommendations were presented online in the Expert Consensus Meeting of the JSHBPS on February 23rd, 2021. The final recommendations were validated and finalized by the 2nd Delphi Round in May 2021. RESULTS: Seven clinical questions were selected, and 22 recommendations were formulated. All recommendations reached more than 85% consensus among experts at the final Delphi Round. CONCLUSIONS: The Expert Consensus Meeting for safely performing MIALR has presented a set of clinical guidelines based on available literature and experts' opinions. We expect these guidelines to have a favorable effect on the safe implementation and development of MIALR.

Minimally invasive anatomic liver resection: Results of a survey of world experts.

BACKGROUND: Although the number of minimally invasive liver resections (MILRs) has been steadily increasing in many institutions, minimally invasive anatomic liver resection (MIALR) remains a complicated procedure that has not been standardized. We present the results of a survey among expert liver surgeons as a benchmark for standardizing MIALR. METHOD: We administered this survey to 34 expert liver surgeons who routinely perform MIALR. The survey contained questions on personal experience with liver resection, inflow/outflow control methods, and identification techniques of intersegmental/sectional planes (IPs). RESULTS: All 34 participants completed the survey; 24 experts (70%) had more than 11 years of experience with MILR, and over 80% of experts had performed over 100 open resections and MILRs each. Regarding the methods used for laparoscopic or robotic anatomic resection, the Glissonean approach (GA) was a more frequent procedure than the hilar approach (HA). Although hepatic veins were considered essential landmarks, the exposure methods varied. The top three techniques that the experts recommended for identifying IPs were creating a demarcation line, indocyanine green negative staining method, and intraoperative ultrasound. CONCLUSION: Minimally invasive anatomic liver resection remains a challenging procedure; however, a certain degree of consensus exists among expert liver surgeons.

The Tokyo 2020 terminology of liver anatomy and resections: Updates of the Brisbane 2000 system.

BACKGROUND: The Brisbane 2000 Terminology for Liver Anatomy and Resections, based on Couinaud's segments, did not address how to identify segmental borders and anatomic territories of less than one segment. Smaller anatomic resections including segmentectomies and subsegmentectomies, have not been well defined. The advent of minimally invasive liver resection has enhanced the possibilities of more precise resection due to a magnified view and reduced bleeding, and minimally invasive anatomic liver resection (MIALR) is becoming popular gradually. Therefore, there is a need for updating the Brisbane 2000 system, including anatomic segmentectomy or less. An online "Expert Consensus Meeting: Precision Anatomy for Minimally Invasive HBP Surgery (PAM-HBP Surgery Consensus)" was hosted on February 23, 2021. METHODS: The Steering Committee invited 34 international experts from around the world. The Expert Committee (EC) selected 12 questions and two future research topics in the terminology session. The EC created seven tentative definitions and five recommendations based on the experts' opinions and the literature review performed by the Research Committee. Two Delphi Rounds finalized those definitions and recommendations. RESULTS: This paper presents seven definitions and five recommendations regarding anatomic segmentectomy or less. In addition, two future research topics are discussed. CONCLUSIONS: The PAM-HBP Surgery Consensus has presented the Tokyo 2020 Terminology for Liver Anatomy and Resections. The terminology has added definitions of liver anatomy and resections that were not defined in the Brisbane 2000 system.

Linear Pinched Hemorrhoidectomy: A Retrospective Observational Study (An Innovative, Simplified Hemorrhoidectomy).

OBJECTIVES: There was an urgent need to create a simple, reliable hemorrhoidectomy procedure for high-risk cases in our university hospital. We performed linear pinched hemorrhoidectomy (LPH) and evaluated its effectiveness compared to conventional hemorrhoidectomy (CH). METHODS: We included 215 Goligher grade 3 and 4 hemorrhoid cases in this study. Of these cases, 167 were in the CH group, and 48 patients were in the LPH group. We retrospectively compared the lengths of hospital stay, operative times, blood loss, and complications. RESULTS: The age tended to be higher in the LPH group (mean: CH 60 years, LPH 68 years). In the univariate analysis, LPH had more resections, shorter operative times, and less blood loss. LPH had shorter operative times in the multivariate analysis, less blood loss, and more anticoagulant use. There were no significant differences between the two groups in terms of complications. Five and two patients in the CH and LPH groups, respectively, had postoperative hemorrhage requiring hemostasis. Only the CH group had three and four cases of anal stenosis and wound edema, respectively. CONCLUSIONS: We studied simplified hemorrhoidectomy using an ultrasonic scalpel and cylindrical proctoscope in a university hospital. We found that it a useful procedure with few complications and was easy for residents to learn. We believe that advances in surgical devices will make it possible to perform safer and simpler hemorrhoidectomy in the future.

Multicenter Propensity Score-Based Study of Laparoscopic Repeat Liver Resection for Hepatocellular Carcinoma: A Subgroup Analysis of Cases with Tumors Far from Major Vessels.

Less morbidity is considered among the advantages of laparoscopic liver resection (LLR) for HCC patients. However, our previous international, multi-institutional, propensity score-based study of emerging laparoscopic repeat liver resection (LRLR) failed to prove this advantage. We hypothesize that these results may be since the study included complex LRLR cases performed during the procedure's developing stage. To examine it, subgroup analysis based on propensity score were performed, defining the proximity of the tumors to major vessels as the indicator of complex cases. Among 1582 LRLR cases from 42 international high-volume liver surgery centers, 620 cases without the proximity to major vessels (more than 1 cm far from both first-second branches of Glissonian pedicles and major hepatic veins) were selected for this subgroup analysis. A propensity score matching (PSM) analysis was performed based on their patient characteristics, preoperative liver function, tumor characteristics and surgical procedures. One hundred and fifteen of each patient groups of LRLR and open repeat liver resection (ORLR) were earned, and the outcomes were compared. Backgrounds were well-balanced between LRLR and ORLR groups after matching. With comparable operation time and long-term outcome, less blood loss (283.3±823.0 vs. 603.5±664.9 mL, p = 0.001) and less morbidity (8.7 vs. 18.3 %, p = 0.034) were shown in LRLR group than ORLR. Even in its worldwide developing stage, LRLR for HCC patients could be beneficial in blood loss and morbidity for the patients with less complexity in surgery.

Intraoperative guidance using ICG fluorescence imaging system for safe and precise laparoscopic liver resection.

BACKGROUND: Laparoscopic liver resection (LLR) has been spread as minimally invasive surgery for liver disease. Advances in surgical technique and devices enabled us to perform various procedures of LLR. Indocyanine green (ICG) fluorescence imaging has been suggested as useful tool to identify liver tumors, anatomical territory of liver parenchyma, and cholangiography in open liver surgery. Due to recent development, this technology can be applied in LLR. we describe safe and effective using of the ICG fluorescence imaging during LLR. METHODS: From September 2013 to August 2019, 34 patients were performed LLR using a total of 46 procedures by ICG fluorescence imaging system for purposes including identification of anatomic domain of the liver in 12 LLRs, detection of liver tumors in 30 nodules, or intraoperative cholangiography in 4 LLRs. RESULTS: During the detection of liver tumors, 25 nodules in 30 malignant to benign tumors were positively detected (83.3%). Although there has been no publication regarding information on ICG fluorescence imaging of low grade malignant or benign tumors, we found positive emission in focal nodular hyperplasia, an angiomyolipoma, and an intraductal papillary neoplasm of the bile duct. The identification of anatomic domain in the liver was successful in all 12 LLRs with negative and positive staining techniques. In the intraoperative cholangiography, all 4 tests were successfully performed. One of 4 patients were found to have biliary leakage which was repaired intraoperatively. CONCLUSIONS: The ICG fluorescence imaging could be useful in safe and precise performance of LLR.

Safety assessment of laparoscopic liver resection: A project study of the Endoscopic Liver Surgery Study Group of Japan.

BACKGROUND/PURPOSE: Laparoscopic liver resection (LLR) has been expanded rapidly and has been accepted worldwide; however, the safety assessment of LLR has not been fully conducted with a large-scale cohort. The aim of this study was to assess safety and identify clinical factors associated with postoperative major complications in LLR. METHODS: This project study retrospectively collected the data of LLRs performed before October 2015 in Japan. Patient characteristics, details of LLRs, and surgical outcomes were analyzed. RESULTS: A total of 4122 patients from 66 institutions were enrolled. The main indications were hepatocellular carcinoma (HCC) and colorectal liver metastases. The majority of the procedures were performed for solitary tumor-located liver segment 2, 3, 5, and 6 and the partial resection and left-lateral sectionectomy occupied 77.3%. The rate of conversion, accidental events were 7.1% and 2.1%, respectively. Postoperative major complication occurred in 205 cases (5.0%), and 14 in-hospital deaths were found among HCC patients with chronically diseased liver. Occurrence of postoperative major complication was associated with operation time (≥360 minutes), intraoperative blood loss (≥250 mL), red blood cell transfusion (yes), and the difficulty score (≥6). The 30- and 90-day mortality was 0.14% and 0.41%, respectively. CONCLUSIONS: Laparoscopic liver resection was performed with an acceptable rate of conversion, accidental events, morbidity, and mortality. The indications for LLR should be cautiously judged considering tumor location, planned operative procedure, and liver function.

Safe Dissemination of Laparoscopic Liver Resection in 27,146 Cases Between 2011 and 2017 From the National Clinical Database of Japan.

OBJECTIVE: To investigate the frequency of laparoscopic liver resection (LLR) nationwide in Japan. BACKGROUND: LLR was initially limited to basic liver resection, but is becoming more common in advanced liver resection. METHODS: Retrospective observational study of 148,507 patients registered in the National Clinical Database 2011-2017. Excluded: liver resection with biliary and vascular reconstruction. RESULTS: LLR or open liver resection (OLR) was performed in 1848 (9.9%) and 16,888 (90.1%) patients, respectively, in 2011, whereas in 2017, LLR had increased to 24.8% and OLR decreased to 75.2% of resections (5648 and 17,099 patients, respectively). There was an annual increasing trend of LLR, starting at 9.9%, then 13.8%, 17.3%, 21.2%, 18.1%, 21.0%, and finally 24.8% in 2017. Basic LLR became more common, up to 30.8% of LR in 2017. Advanced LLR increased from 3.3% of all resections in 2011 to 10.8% in 2017. Throughout the years observed, there were fewer complications in LLR than OLR. Operative mortality was 3.6% for both advanced LLR and OLR in 2011, and decreased to 1.0% and 2.0%, respectively, in 2017. Mortality for both basic LLR and basic OLR were low and did not change throughout the study, at 0.5% and 1.6%, respectively, in 2011 and 0.5% and 1.1%, in 2017. CONCLUSIONS: LLR has rapidly become widespread in Japan. Basic LLR is now a standard option, and advanced LLR, while not as common yet, has been increasing year by year. LLR has been safely developed with low mortality and complications rate relative to OLR.

A Multicenter Phase 2 Trial to Evaluate the Efficacy of mFOLFOX6 + Cetuximab as Induction Chemotherapy to Achieve R0 Surgical Resection for Advanced Colorectal Liver Metastases (NEXTO Trial).

BACKGROUND: The effect of cetuximab plus mFOLFOX on downsizing of the tumors for curative resection has yet to be assessed for patients with advanced colorectal liver metastases (CRLMs). This study aimed to assess the oncologic benefit of cetuximab plus mFOLFOX for wild-type KRAS patients with advanced CRLMs. METHODS: In this multicenter phase 2 trial, patients with technically unresectable tumor and/or five or more CRLMs harboring wild-type KRAS were treated with mFOLFOX plus cetuximab. The patients were assessed for resectability after 4 treatments, and then every 2 months up to 12 treatments. Patients with resectable disease were offered surgery after a waiting period of 1 month. The primary end point of the study was the R0 resection rate. The secondary end points were safety, progression-free survival (PFS), and overall survival (OS). The study is registered with the University Hospital Medical Information Network-Clinical Trials Registry Clinical Trials Registry (no. C000007923). RESULTS: Between 2012 and 2015, 50 patients from 13 centers were enrolled in this trial. Two patients were excluded because they had not received induction therapy. The 48 patients had a complete response rate of 0% and a partial response rate of 64.6%. For 26 R0 resections (54.2%) and 5 R1 resections (10.4%), no mortality occurred. During a median follow-up period of 31 months, the median OS for all the patients was calculated to be 41 months (95% confidence interval, 28-not reached). The 3-year OS rate was 59%. CONCLUSION: For patients with advanced CRLMs harboring wild-type KRAS, cetuximab administered in combination with mFOLFOX yields high response rates, leading to significantly high R0 resection rates and favorable prognoses.

Six autoantibodies as potential serum biomarkers of hepatocellular carcinoma: A prospective multicenter study.

Serum autoantibodies have been reported to react with tumor-associated antigen (TAA) in various cancers. This multicenter study evaluated the diagnostic and prognostic value of six autoantibodies against a panel of six hepatocellular carcinoma (HCC)-associated antigens, including Sui1, p62, RalA, p53, NY-ESO-1 and c-myc. A total of 160 patients with HCC and 74 healthy controls were prospectively enrolled from six institutions. Serum antibody titers were determined by enzyme-linked immunosorbent assays. The sensitivities were 19% for Sui1, 18% for p62, 17% for RalA, 11% for p53, 10% for NY-ESO-1 and 9% for c-myc. Overall sensitivity of the TAA panel (56%) was higher than that of α-fetoprotein (41%, P < .05). The combined sensitivity of the TAA panel and α-fetoprotein was significantly higher than that of α-fetoprotein alone (P < .001). The difference in overall survival of TAA panel-positive and panel-negative patients was significant when the Stage I/II patients were combined (P = .023). Overall survival was worse in NY-ESO-1 antibody-positive than in NY-ESO-1 antibody-negative patients (P = .002). Multivariate analysis found that positivity for the TAA panel was independently associated with poor prognosis (P = .030). This TAA panel may have diagnostic and prognostic value in the patients with HCC.

Validation and performance of three-level procedure-based classification for laparoscopic liver resection.

BACKGROUND: A procedure-based laparoscopic liver resection (LLR) classification (IMM classification) stratified 11 different LLR procedures into 3 grades. IMM classification assessed the difficulty of LLR differently than an index-based LLR classification (IWATE criteria), which scored each procedure on an index scale of 12. We validated the difference of 3 IMM grades using an external cohort, evaluated the IMM classification using the scores of the IWATE criteria, and compared the performance of IMM classification with the IWATE criteria and the minor/major classification. METHODS: Patients undergoing LLR without simultaneous procedures were selected from a prospectively maintained database at the Institut Mutualiste Montsouris (IMM cohort) and from the database of 43 Japanese institutions (JMI cohort). Surgical and postoperative outcomes were evaluated according to the 3 IMM grades using the JMI cohort. The 11 LLR procedures included in the IMM classification were scored according to the IWATE criteria. The area under the curves (AUCs) for surgical and postoperative outcomes were compared. RESULTS: In the JMI (n = 1867) cohort, operative time, blood loss, conversion rate, and major complication rate were significantly associated with a stepwise increase in grades from I to III (all, P < 0.001). In the IMM (n = 433) and JMI cohorts, IMM grades I, II, and III corresponded to three low-scoring, two intermediate-scoring, and six high-scoring LLR procedures as per the IWATE criteria, respectively. Mean ± standard deviation among the IMM grades were significantly different: 3.7 ± 1.4 (grade I) versus 7.5 ± 1.7 (grade II) versus 10.2 ± 1.0 (grade III) (P < 0.001) in the IMM cohort and 3.6 ± 1.4 (grade I) versus 6.7 ± 1.5 (grade II) versus 9.3 ± 1.4 (grade III) (P < 0.001) in the JMI cohort. The AUCs for surgical and postoperative outcomes are higher for the 3-level IMM classification than for the minor/major classification. CONCLUSIONS: The difference of 3 IMM grades with respect to surgical and postoperative outcomes was validated using an external cohort. The 3-level procedure-based IMM classification was in accordance with the index-based IWATE criteria. The IMM classification performed better than the minor/major classification for stratifying LLR procedures.