title: Tensile strength and failure load of sutures for robotic surgery.
abstract: Robotic surgical platforms have seen increased use among minimally invasive gastrointestinal surgeons (von Fraunhofer et al. in J Biomed Mater Res 19(5):595-600, 1985. doi: 10.1002/jbm.820190511 ). However, these systems still suffer from lack of haptic feedback, which results in exertion of excessive force, often leading to suture failures (Barbash et al. in Ann Surg 259(1):1-6, 2014. doi: 10.1097/SLA.0b013e3182a5c8b8 ). This work catalogs tensile strength and failure load among commonly used sutures in an effort to prevent robotic surgical consoles from exceeding identified thresholds. Trials were thus conducted on common sutures varying in material type, gauge size, rate of pulling force, and method of applied force.
  
  
  
  Polydioxanone, Silk, Vicryl, and Prolene, gauges 5-0 to 1-0, were pulled till failure using a commercial mechanical testing system. 2-0 and 3-0 sutures were further tested for the effect of pull rate on failure load at rates of 50, 200, and 400 mm/min. 3-0 sutures were also pulled till failure using a da Vinci robotic surgical system in unlooped, looped, and at the needle body arrangements.
  
  
  
  Generally, Vicryl and PDS sutures had the highest mechanical strength (47-179 kN/cm2), while Silk had the lowest (40-106 kN/cm2). Larger diameter sutures withstand higher total force, but finer gauges consistently show higher force per unit area. The difference between material types becomes increasingly significant as the diameters decrease. Comparisons of identical suture materials and gauges show 27-50% improvement in the tensile strength over data obtained in 1985 (Ballantyne in Surg Endosc Other Interv Tech 16(10):1389-1402, 2002. doi: 10.1007/s00464-001-8283-7 ). No significant differences were observed when sutures were pulled at different rates. Reduction in suture strength appeared to be strongly affected by the technique used to manipulate the suture.
  
  
  
  Availability of suture tensile strength and failure load data will help define software safety protocols for alerting a surgeon prior to suture failure during robotic surgery. Awareness of suture strength weakening with direct instrument manipulation may lead to the development of better techniques to further reduce intraoperative suture breakage.
authors.affiliation: UCLA Center for Advanced Surgical and Interventional Technology (CASIT), Los Angeles, CA, USA. aabiri@ucla.edu.|UCLA Henry Samueli School of Engineering and Applied Science, Los Angeles, CA, USA. aabiri@ucla.edu.
authors.forename: Ahmad
authors.identifier: 0000-0002-4709-5479
authors.initials: A
authors.lastname: Abiri
authors.affiliation: UCLA Center for Advanced Surgical and Interventional Technology (CASIT), Los Angeles, CA, USA.|UCLA Henry Samueli School of Engineering and Applied Science, Los Angeles, CA, USA.
authors.forename: Omeed
authors.initials: O
authors.lastname: Paydar
authors.affiliation: UCLA Center for Advanced Surgical and Interventional Technology (CASIT), Los Angeles, CA, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Tao
authors.affiliation: UCLA Center for Advanced Surgical and Interventional Technology (CASIT), Los Angeles, CA, USA.
authors.forename: Megan
authors.initials: M
authors.lastname: LaRocca
authors.affiliation: UCLA Center for Advanced Surgical and Interventional Technology (CASIT), Los Angeles, CA, USA.
authors.forename: Kang
authors.initials: K
authors.lastname: Liu
authors.affiliation: UCLA Center for Advanced Surgical and Interventional Technology (CASIT), Los Angeles, CA, USA.|UCLA Department of Surgery, Los Angeles, CA, USA.
authors.forename: Bradley
authors.initials: B
authors.lastname: Genovese
authors.affiliation: UCLA Center for Advanced Surgical and Interventional Technology (CASIT), Los Angeles, CA, USA.|UCLA Henry Samueli School of Engineering and Applied Science, Los Angeles, CA, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Candler
authors.affiliation: UCLA Center for Advanced Surgical and Interventional Technology (CASIT), Los Angeles, CA, USA.|UCLA Henry Samueli School of Engineering and Applied Science, Los Angeles, CA, USA.
authors.forename: Warren S
authors.initials: WS
authors.lastname: Grundfest
authors.affiliation: UCLA Center for Advanced Surgical and Interventional Technology (CASIT), Los Angeles, CA, USA.|UCLA Department of Surgery, Los Angeles, CA, USA.
authors.forename: Erik P
authors.initials: EP
authors.lastname: Dutson
mesh_terms: D019544:Equipment Failure Analysis; D008422:Materials Testing / Q000379:methods; D016687:Polydioxanone; D011098:Polyglactin 910; D011126:Polypropylenes; D065287:Robotic Surgical Procedures / Q000592:standards*; D013536:Suture Techniques / Q000295:instrumentation / Q000592:standards*; D013537:Sutures / Q000592:standards*; D013718:Tensile Strength
chemical_list: D011126:Polypropylenes; D016687:Polydioxanone; D011098:Polyglactin 910
keywords: Da Vinci; Force sensor; Robotic surgery; Surgical platform; Suture; Suture tensile strength