A randomised controlled trial to establish the effect of articulating instruments upon performance and learning curve in Single Incision Laparoscopic Surgery

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

Imperial College London

Introduction
Placing both instruments and laparoscope through one incision presents unique technical challenges. Such challenges result in a longer learning curve for SILS when compared to conventional laparoscopy. In addition, surgeons have reported higher workload with SILS. Articulating instruments may counter these difficulties but no consensus exists as to their benefit. Some authors report reduced performance whereas some show improvements over or equivalence with conventional, straight instrumentation. It was these conflicting results that the current study aimed to address. The primary objectives of this randomised controlled trial were to evaluate the effects of articulating instruments upon performance and learning curve in Single Incision Laparoscopic Surgery (SILS). The secondary outcome assessed was workload. The hypothesis was that these instruments would affect performance, learning curve and workload.

Methods and procedures
Surgeons having completed five or more laparoscopic cases as primary operator were recruited. For baseline testing surgeons completed one repetition of the Fundamentals of Laparoscopic Surgery (FLS) peg transfer (PEG) and pattern cutting (CUT) tasks using a conventional laparoscopic setup. They were then randomised to straight (STR), one articulating and one straight (STR-ART) or two articulating instruments (ART) and performed 25 PEG repetitions using a SILS setup. Performance was assessed by calculating maximum FLS scores and analysing hand motion using the Imperial College Surgical Assessment Device (ICSAD). Workload was assessed using the validated NASA Raw Task Load Index (NASA-RTLX) questionnaire. Non-linear regression modelling determined surgeons’ theoretical maximal performance given infinite practice (learning plateau) and the predicted number of repetitions required to achieve 90% of this (learning rate). Surgeons were later invited to perform 5 CUT repetitions using SILS. Minimum times and errors made were compared between groups. The Kruskal-Wallis test was used to compare groups. Where significant differences emerged, Mann-Whitney U tests were used for post-hoc pairwise comparisons. P values <0.05 were considered significant.

Results
Twenty-one surgeons were recruited; STR (n=7), STR-ART (n=7) or ART (n=7), with no significant differences in baseline FLS scores (p=0.63) or number of cases performed (p=0.94). STR-ART demonstrated significantly higher maximum FLS scores than STR or ART (239 vs. 228 vs. 210, respectively, p=0.002). Learning rate did not differ significantly (2.70 vs. 5.25 vs. 5.41, respectively, p=0.757) although learning plateau was significantly higher in STR-ART (208 vs. 157 vs. 109, respectively, p=0.007). No significant differences were found in total path length (p=0.55) or total number of movements (p=0.08). No significant differences were found in NASA-RTLX scores (p=0.708). Fifteen surgeons completed CUT; STR (n=5), STR-ART (n=5) and ART (n=5). No significant differences were found in the minimum times (153s vs. 110s vs. 151s, respectively, p=0.129) or the minimum number of errors made (0 vs. 1 vs. 1, respectively, p=0.702).

Conclusions
The use of one straight and one articulating instrument took no longer to learn, required no significant alteration in hand movements, contributed no additional workload and conferred improved performance in the peg transfer task. When its use was extended to the pattern cutting task, performance remained unimpaired. Therefore, this may represent the optimal instrument configuration for clinical SILS.

Session: Poster Presentation

Program Number: P506