title: Insufficient joint forces of first-generation articulating instruments for laparoendoscopic single-site surgery.
abstract: BACKGROUND
  The current articulating instruments used in laparoendoscopic single-site surgery do not appear to provide the joint forces required. Thus, we measured the joint forces of first-generation articulating laparoscopic instruments. To compare these forces with those necessary in the surgical context, we evaluated the forces sufficient to produce secure surgical ties in an animal model.
  
  
  METHODS
  The articulating instruments tested were Laparo-Angle (Cambridge Endoscopic Devices Inc, Framingham, MA), RealHand (Novare Surgical Systems Inc, Cupertino, CA), and Roticulator (Covidien Inc, Mansfield, MA). For each, we measured the angle between the end-effector and the shaft in proportion to the articulating force using a push-pull gauge. Two fixed-position configurations of the instruments were predetermined: the neutral and the fully articulated positions. The forces required to secure surgical ties for the ureter, renal artery, and renal vein were evaluated using kidneys harvested from a female pig.
  
  
  RESULTS
  The bending forces required to bend from the neutral position to 30° were 5.6 ± 1.2 and 4.7 ± 1.0 N with the Laparo-Angle and RealHand, respectively. Furthermore, the slippage forces in the fully articulated state were 1.8 ± 0.3, 1.6 ± 0.2, and 1.5 ± 0.2 N in the above order. In contrast, the mean forces to produce surgical ties of the ureter, renal artery, and renal vein were 14.5 ± 2.3, 11.5 ± 0.8, and 10.3 ± 2.3 N, respectively.
  
  
  CONCLUSIONS
  The joint forces of first-generation articulating instruments for laparoendoscopic single-site surgery are not sufficient to meet the usual operative needs. Improved articulating instruments with greater articulating forces should be developed.
authors.affiliation: 1Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Chang Wook
authors.initials: CW
authors.lastname: Jeong
authors.forename: Sung Hoon
authors.initials: SH
authors.lastname: Kim
authors.forename: Hyung Tae
authors.initials: HT
authors.lastname: Kim
authors.forename: Seong Jin
authors.initials: SJ
authors.lastname: Jeong
authors.forename: Sung Kyu
authors.initials: SK
authors.lastname: Hong
authors.forename: Seok-Soo
authors.initials: SS
authors.lastname: Byun
authors.forename: Sang Eun
authors.initials: SE
authors.lastname: Lee
mesh_terms: D000818:Animals; D005260:Female; D007668:Kidney / Q000601:surgery; D020706:Laparoscopes; D010535:Laparoscopy / Q000295:instrumentation* / Q000379:methods; D055595:Mechanical Phenomena; D008962:Models, Theoretical; D013552:Swine