title: Single-incision laparoscopic cholecystectomy with curved versus linear instruments assessed by systematic review and network meta-analysis of randomized trials.
abstract: BACKGROUND
  Single-incision laparoscopic surgery poses significant ergonomic limitations. Curved instruments have been developed in order to address the issue of lack of triangulation. Direct comparison between single-incision laparoscopic surgeries with conventional linear and curved instruments has not been performed to date.
  
  
  METHODS
  MEDLINE, CENTRAL and OpenGrey were searched to identify relevant randomized trials. A network meta-analysis was applied to compare operative risks, conversion, duration of surgery and the need for placement of an adjunct trocar in single-incision laparoscopic cholecystectomy with linear and curved instruments. The random-effects model was applied for two sets of comparisons, with conventional laparoscopic cholecystectomy as the reference treatment. Odds ratios, mean differences and 95% confidence intervals were calculated.
  
  
  RESULTS
  Twenty-three randomized trials encompassing 1737 patients were included. The use of curved instruments was associated with increased operative time (mean difference 32.53 min, 95% CI 24.23-40.83) and higher odds for the use of an adjunct trocar (odds ratio 22.81, 95% CI 16.69-28.94) compared to the use of linear instruments. Perioperative risks could not be comparatively assessed due to the low number of events.
  
  
  CONCLUSIONS
  Single-incision laparoscopic cholecystectomy with curved instruments may be associated with an increased level of operative difficulty, as reflected by the need for auxiliary measures for exposure and increased operative time as compared to the use of linear instruments. Current instrumentation requires further improvement, tailored to the features of single-incision laparoscopic surgery (CRD42015015721).
authors.affiliation: Center for Minimally Invasive Surgery, Hospital Neuwerk, Mönchengladbach, Germany. stavros.antoniou@hotmail.com.|Department of General Surgery, University Hospital of Heraklion, Crete, Greece. stavros.antoniou@hotmail.com.|, Athinon-Souniou 11, 19001, Keratea Attikis, Athens, Greece. stavros.antoniou@hotmail.com.
authors.forename: Stavros A
authors.initials: SA
authors.lastname: Antoniou
authors.affiliation: Unit of Innovation in Minimally Invasive Surgery, Unidad de Gestión Clínica de Cirugía General y Aparato Digestivo, University Hospital Virgen del Rocío, Seville, Spain.
authors.forename: Salvador
authors.initials: S
authors.lastname: Morales-Conde
authors.affiliation: Liverpool Vascular and Endovascular Service, Royal Liverpool University Hospital, Liverpool, UK.
authors.forename: George A
authors.initials: GA
authors.lastname: Antoniou
authors.affiliation: Department of General Surgery, Hospital Zell am See, Zell Am See, Austria.
authors.forename: Rudolph
authors.initials: R
authors.lastname: Pointner
authors.affiliation: Center for Minimally Invasive Surgery, Hospital Neuwerk, Mönchengladbach, Germany.
authors.forename: Frank-Alexander
authors.initials: FA
authors.lastname: Granderath
mesh_terms: D017081:Cholecystectomy, Laparoscopic / Q000295:instrumentation*; D004867:Equipment Design; D006801:Humans; D061646:Operative Time; D011183:Postoperative Complications; D016032:Randomized Controlled Trials as Topic; D013525:Surgical Instruments
keywords: Cholecystectomy; Instruments technical; Laparoscopic; SILS; Single-incision