Abstract
Introduction
An emerging consensus in the surgical specialties is that skill acquisition should be more emphasized during surgical training.1 This study was an attempt to evaluate the effects of repetitive practices using an image-free computer-assisted orthopaedic surgery (CAOS) guidance system (Exactech GPS, Blue-Ortho, Grenoble, FR) on both technical and cognitive skills.
Materials and methods
A senior knee replacement surgeon with limited previous experience with the CAOS system performed a series of consecutive simulated knee surgeries using a commercially available artificial leg (MITA trainer leg M-00058, Medical Models, Bristol, UK).
In order to assess the effects repetitive practice has on technical skills, we evaluated two indexes:
Error index: A unitless indication of overall error magnitude obtained by averaging the absolute values of all linear and angular measurement differences between targeted and checked cuts.
Time index: An indication of the time required to acquire landmarks, adjust the custom blocks, and make cuts.
In order to assess the effect repetitive practice has on cognitive skills, we evaluated the number of times the surgeon elected to deviate from pre-surgical planning or re-acquire landmarks.
We evaluated these parameters for three chronological and consecutive groups of simulated surgeries: Group A (knee models #1 to #10), Group B (knee models #11 to #20), and Group C (knee models #21 to #28).
Results
Regardless of the number of operations, tibial and femoral cuts were associated with a low error index (ranging from 0.45 to 0.71 for all three groups), suggesting the continuous guidance offered by the CAOS system provided an opportunity to correct discrepancies from the plan during surgery (Figure 1A). The variability of surgical time at key steps substantially reduced from Group A to Group C (Figure 1B). Finally, the surgeon elected to re-perform femoral landmark acquisitions 8 times for Group A, 4 times for Group B, and 0 times for Group C.
Discussion
The authors attempted to delineate the effects of repetitive practices on skills using a CAOS system. The overall perception was the number of sequential practice surgeries had no significant effect on surgical accuracy. The significant decrease in the time index (43%) during the course of the practice surgeries is in line with recent studies regarding the learning curve associated with navigation for knee arthroplasty.2 Compared to the initial planning, the only modifications in surgical steps were related to re-acquiring femoral landmarks. As with any image-free system, the present CAOS system relies on precise landmark acquisition. To achieve this goal, the system under consideration presents an interactive software enabling landmark visualization (Figure 2) allowing immediate feedback loop.
Despite the obvious limitation of being conducted on synthetic bones, this study enabled a senior surgeon to perfect his technical and cognitive skills, potentially leading to increases in efficiency and efficacy in the intense environment of the operating room.
