Retropubic trocar modified with a load cell to verify contact with pubic bone



      Vital injuries during midurethral sling surgery are avoided by maintaining constant trocar contact with bone, and yet this is challenging for a teaching surgeon to monitor during this blind procedure. We modified a retropubic trocar with a load cell to distinguish on-bone and off-bone movement and tested it on a midurethral sling surgery 3-dimensional surgery simulator.


      Two experts and 3 novice surgeons performed retropubic trocar passage on the physical pelvic floor model using the modified trocar. Biofidelity was assessed comparing expert performance on a Thiel-embalmed cadaver and the physical model. The test-retest was assessed comparing performance on the physical pelvic model 2 weeks apart. The force variables were analyzed with paired and independent t tests. We performed post hoc analyses comparing the experts to novices on the physical model.


      The root-mean-squared force was similar between the cadaver and model (24.3 vs 21.1 pounds, P = .62), suggesting biofidelity. Root-mean-squared force was also similar between the test and retest (14.0 vs 19.1 pounds, P =. 30). The expert surgeons exhibited a larger maximum force amplitude (51.2 vs 22.7 pounds, P = .03), shorter time to maximum force (2.7 vs 9.5 seconds, P = .03) and larger maximum rate of force development (171.5 vs 54.0 pounds/second, P = .01).


      This study suggested high test-retest reliability and adequate biofidelity of the modified trocar used on our midurethral sling surgery 3-dimensional surgery simulator. This innovative trocar can be used both in simulation and in the operating room to help the novice surgeons stay on the bone and to help the attending surgeon monitor safe surgery.
      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Surgery
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Silvennoinen M.
        • Mecklin J.P.
        • Saariluoma P.
        • Antikainen T.
        Expertise and skill in minimally invasive surgery.
        Scand J Surg. 2009; 98: 209-213
        • McLennan M.T.
        • Barr S.A.
        • Melick C.F.
        • Gavard J.A.
        Bladder perforation during tension-free vaginal tape procedures: abdominal versus vaginal approach.
        Female Pelvic Med Reconstr Surg. 2012; 18 (discussion 9–31): 25-29
        • Jonsson Funk M.
        • Levin P.J.
        • Wu J.M.
        Trends in the surgical management of stress urinary incontinence.
        Obstet Gynecol. 2012; 119: 845-851
        • Nager C.
        • Tulikangas P.
        • Miller D.
        • Rovner E.
        • Goldman H.
        Position statement on mesh midurethral slings for stress urinary incontinence.
        Female Pelvic Med Reconstr Surg. 2014; 20: 123-125
        • Pathi S.D.
        • Castellanos M.E.
        • Corton M.M.
        Variability of the retropubic space anatomy in female cadavers.
        Am J Obstet Gynecol. 2009; 201 (524.e1–e5)
        • Blaivas J.G.
        • Purohit R.S.
        • Benedon M.S.
        • et al.
        Safety considerations for synthetic sling surgery.
        Nat Rev Urol. 2015; 12: 481-509
        • Stylianou A.P.
        • Arif M.A.
        • Mahmud F.
        • King G.W.
        • Sutkin G.
        Virtual pelvic model for study of surgeon kinematics during retropubic trocar passage, AUGS/IUGA Scientific Meeting, Nashville, TN.
        Int Urogynecol J. 2019; 30: 190-191
        • Arif MDA
        Virtual pelvic surgery simulator for the prevention of surgical errors [M.S.].
        University of Missouri–Kansas City, 2019
        • Yip S.K.
        • Pang M.W.
        • Sahota D.S.
        Measurement of tension-free vaginal tape trocar insertion and exit forces.
        Gynecol Obstet Invest. 2006; 62: 55-60
      1. Schrope J, Olmanson B, Fick C, et al. The SMART trocar: force, deviation, and impedance sensing trocar for enhanced laparoscopic surgery. 2019 Design of Medical Devices Conference, Minneapolis, MN. American Society of Mechanical Engineers. V001T06A002.

        • Oliphant S.
        • Littleton E.B.
        • Gosman G.
        • Sutkin G.
        Teaching the retropubic midurethral sling using a novel cadaver and model-based approach.
        Cureus. 2017; 9: e1214
        • McDougall E.M.
        Validation of surgical simulators.
        J Endourol. 2007; 21: 244-247
        • Bjerrum F.
        • Thomsen A.S.S.
        • Nayahangan L.J.
        • Konge L.
        Surgical simulation: current practices and future perspectives for technical skills training.
        Med Teach. 2018; 40: 668-675