title: Effect of robotic manipulation on unidirectional barbed suture integrity: evaluation of tensile strength and sliding force.
abstract: OBJECTIVE
  One of the more challenging portions of robot-assisted radical prostatectomy (RARP) is the urethrovesical anastomosis. Because of this, a unidirectional absorbable barbed suture (V-Loc(™)) has been used to complete the anastomosis with better efficiency and less tension. The effect of robotic needle driver manipulation on barbed suture is unknown. Therefore, the aim of this study is to determine whether robotic manipulation decreases the tensile strength and peak sliding force of V-Loc barbed suture.
  
  
  METHODS
  Fifty-six V-Loc sutures were compared with 56 Maxon sutures. All sutures were 3-0 caliber. Half of the sutures in each group were manipulated with a da Vinci(®) robot large needle driver five times over a 5 cm length of suture. The other half was not manipulated. Breaking force was determined by placing sutures in a Bose ElectroForce load testing device. For sliding force testing, 28 V-Loc sutures were manipulated in the same fashion and compared with 28 nonmanipulated V-Loc sutures. Peak force needed to make the suture slip backward in porcine small intestine was determined to be the sliding force. Scanning electron microscopy of the barbs before and after robotic manipulation was also performed.
  
  
  RESULTS
  The mean difference in breaking forces for manipulated vs nonmanipulated Maxon sutures was 4.52 N (P=0.004). The mean difference in breaking forces for manipulated vs nonmanipulated V-Loc sutures was 1.30 N (P=0.046). The manipulated V-Loc group demonstrated a lower peak sliding force compared with the nonmanipulated group (0.76 vs 0.88 N, P=0.199). Electron microscopy revealed minor structural damage to the barbs and suture.
  
  
  CONCLUSIONS
  Tensile strength and peak sliding force of V-Loc suture is decreased by robotic manipulation. This is likely because of structural damage to the suture and barbs. This structural damage, however, is likely not clinically significant.
authors.affiliation: Division of Urology, University of Nebraska Medical Center, Omaha, Nebraska 68198, USA.
authors.forename: Dharam
authors.initials: D
authors.lastname: Kaushik
authors.forename: Kevin
authors.initials: K
authors.lastname: Clay
authors.forename: S G M
authors.initials: SG
authors.lastname: Hossain
authors.forename: Eugene
authors.initials: E
authors.lastname: Park
authors.forename: Carl A
authors.initials: CA
authors.lastname: Nelson
authors.forename: Chad A
authors.initials: CA
authors.lastname: LaGrange
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena / Q000502:physiology; D007422:Intestines / Q000601:surgery; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D012371:Robotics / Q000379:methods*; D034421:Sus scrofa; D013537:Sutures; D013718:Tensile Strength