A Randomised Controlled Trial to Evaluate the Impact of Instrument and Laparoscope Length on Performance and Learning Curve in Single Incision Laparoscopic Surgery

Sathyan Balaji, BSc, Pritam Singh, MBBS, MA, MRCS, Mikael H Sodergren, MBBS, MRCS, PhD, Harry Corker, BSc, Richard M Kwasnicki, BSc, Ara Darzi, MBBS, MD, KBE, FMedSci, FRCS, FACS, Paraskevas Paraskeva, MBBS, PhD, FRCS

Imperial College London, London, United Kingdom

Introduction:
This randomised controlled trial evaluated the effect of varying instrument length on simulated Single Incision Laparoscopic Surgery (SILS) performance. SILS further reduces the invasiveness of laparoscopic surgery. The potential benefits include enhanced cosmesis and reduced pain. However, instrumentation entering adjacent to each other creates difficulties by reducing triangulation and potentially increasing both internal and external collisions. An innovative method of overcoming some of these challenges is to vary instrumentation length.

Method:
Surgeons were eligible if they had performed a minimum of 5 laparoscopic procedures as primary surgeon. Participants completed baseline testing involving one repetition of both the peg transfer (PEG) and pattern cutting (CUT) tasks from the validated Fundamentals of Laparoscopic Surgery (FLS) curriculum using a conventional laparoscopic setup. Subjects were stratified based on surgical experience and randomised into one of 3 trial arms: The control group used standard length instruments (31cm) and a standard length laparoscope (30cm), Group 1 used 1 longer bariatric length instrument (42cm) and 1 standard length instrument and a standard length laparoscope and Group 2 used standard length instruments and a longer bariatric length laparoscope (42cm). The trial was undertaken in two phases using a validated SILS modified FLS box trainer. Phase one involved 25 repetitions of PEG. Phase two involved 5 repetitions of CUT. FLS scoring parameters and the validated hand tracking Imperial College Surgical Assessment Device (ICSAD) measured performance. NASA TLX workload assessment was issued at trial completion. Learning curves were generated using non-linear regression allowing calculation of the learning plateau (surgeons theoretical maximum performance) and learning rate (number of repetitions to reach 90% of maximum score). A non-parametric approach was used for statistical analysis.

Results:
Twenty-three surgeons were recruited to Control (n=7), Group 1 (n=9) and Group 2 (n=7). There were no significant differences in operative experience or baseline FLS scores of PEG and CUT. Phase 1: Peak FLS score was significantly higher in Group 1 compared to control (p<0.05). Learning curves demonstrated no difference in learning rate; however, Group 1 had a significantly higher learning plateau than control (p<0.05). Fifteen surgeons completed CUT in phase 2: Control (n=5), Group 1 (n=6) and Group 2 (n=4). Group 1 revealed a trend towards higher peak FLS scores over control group (p =0.067). NASA TLX workload assessment showed participants in Group 2 (P<0.05) subjectively perceived higher performance than control. ICSAD revealed no significant differences in total path length or number of hand movements between groups in both phases.

Conclusions:
This study demonstrates that varying instrument length can improve performance in a simulated SILS model. The combination of 1 bariatric length and 1 standard length instrument conferred highest performance. This could be a feasible and simple solution to optimise SILS ergonomics with equipment readily available in many minimally invasive surgical units.

Session: Podium Presentation

Program Number: S078