Evaluation of Scissor Glide Characteristics Through Surgeons' Subjective Assessment: The Application of Nitriding in Scissor Hardening Tests.

ABSTRACT

INTRODUCTION: In robotic surgery, studies on providing tactile feedback to users are ongoing. However, the accuracy of the subjective sensations of surgeons, as users, has been largely unassessed. This study aimed to assess the validity of surgeons' subjective evaluations of scissors resistance through interindividual, inter-surgeon, and objective evaluations. Furthermore, in this study, we explored the possibility of using nitriding to increase the hardness of the scissors and assessed changes in subjective resistance values before and after nitriding using this approach. METHOD: Five surgeons conducted validation of five curved surgical scissors (145 mm; Arakawa Seisakujyo Co., Ltd., Tokyo, Japan) and assessed their subjective resistance using a scale from 0 to 10, where a rating of 10 signified significant resistance impeding the scissors' closure. The temporal changes in subjective resistance values, from maximum open to close, were graphically recorded. To demonstrate the reproducibility of subjective resistance values, the subjective resistance values of the same control scissors were measured at intervals of at least two weeks, and the correlation coefficient was calculated. To analyze the closing characteristics of subjective resistance values between different pairs of scissors, the effect of scissor type and scissor closure position was compared as two independent variables using a two-factor analysis of variance. A comparative evaluation was conducted to assess the frictional properties of scissors after nitriding, comparing the subjective assessment by surgeons with the objective assessment using a digital force gauge. RESULTS: The correlation coefficient of subjective resistance values measured by surgeons demonstrated a high reproducibility of 0.746. A two-factor analysis of variance conducted on subjective resistance values demonstrated the presence of a primary effect for the sample factor (scissors), as well as for the position factor (closing process), with the additional observation of the interaction between these two factors. The results from the two-factor analysis of variance above provide evidence supporting the validity of the subjective resistance measurements. There was a significant increase in subjective resistance after the nitriding process. The graph of subjective resistance values and objective resistance values showed similarity. CONCLUSIONS: The surgeons' subjective assessment of scissors resistance showed high reproducibility and validity, as evidenced by distinguishable differences in scissor movement interactions and pre- and post-nitriding resistance. Further studies are warranted to expand on these findings.