D. N. Rutherford1, A. D. D’Angelo1, C. Kwan1, P. B. Barlow1, C. M. Pugh1 1University Of Wisconsin,Department Of Surgery, School Of Medicine And Public Health,Madison, WI, USA 2University Of Wisconsin,Department Of Kinesiology, School Of Education,Madison, WI, USA
Introduction: Port placement is critical for surgical performance. Quantification of port selection may improve assessment of laparoscopic skill. The study aim was to use a novel objective method to assess port placement.
Methods: Twenty PGY 2-3 surgery residents from Midwestern programs completed a port placement assessment indicating locations for 5mm and 12mm ports on images of four hernias: epigastric, right lower quadrant (RLQ) incisional, right inguinal, and umbilical. Three of four possible hernias were randomly selected for assessment. The researchers then created a two-dimensional coordinate grid, and assigned coordinates to port locations on each image. The inguinal hernia was subdivided into total extra-peritoneal (TEP), trans-abdominal pre-peritoneal (TAPP) and other given differences in port placement for these procedures. Hierarchical cluster analysis (HCA) was used to group clusters of 5mm and 12mm port locations for each hernia. Clusters were defined using Ward’s method for linking squared Euclidean distances. The resultant distances of port cluster centers to the edges of the hernias were calculated.
Results:All participants completed the port placement assessment (epigastric (N=6), right umbilical (N=14), right inguinal (N=20) and RLQ incisional (N=20)). Figure 1 depicts distances from cluster center to hernia edge. For 5mm ports, the amount of variance in port to hernia distance was significantly different between hernias (Levene's test of variance F(6,28)=4.029, p<.005). The other approach for the inguinal hernia contained the most variance, whereas the epigastric had the least. Residents who chose methods other than TEP or TAPP for the right inguinal showed similar port placements to those observed for the RLQ incisional hernia. Multiple positions for 12mm ports were consistently either near (7.98-8.75cm) or far (11.7-15.3cm) from the hernia edge. For 12mm ports, the amount of variance in port to hernia distance was significantly different between different hernias (Levene's test of variance F(6,28)=2.83, p<.028). Both Inguinal TAP and TEP had the least amount of variance and the incisional hernia had the most.
Conclusion:HCA was successfully used to classifying variability in port placement. The amount of variability in port distance to hernia edge differed depending on the type of hernia. Interestingly, those participants that did not use the TEP or TAPP approach, demonstrated clusters similar to the RLQ incisional hernia repair despite different anatomic considerations with these repairs. Future work will focus on employing cluster analysis to investigate expert-novice differences and other factors central to port placement, including between port distance and port pattern angles.
