Navigation forces during wrist arthroscopy: assessment of expert levels.

PURPOSE: To facilitate effective and efficient training in skills laboratory, objective metrics can be used. Forces exerted on the tissues can be a measure of safe tissue manipulation. To provide feedback during training, expert threshold levels need to be determined. The purpose of this study was to define the magnitude and the direction of navigation forces used during arthroscopic inspection of the wrist. METHODS: We developed a set-up to mount a cadaver wrist to a 3D force platform that allowed measurement of the forces exerted on the wrist. Six experts in wrist arthroscopy performed two tasks: (1) Introduction of the camera and visualization of the hook. (2) Navigation through the wrist with visualization of five anatomic structures. The magnitude (Fabs) and direction of force were recorded, with the direction defined as α being the angle in the vertical plane and ß being the angle in the horizontal plane. The 10th-90th percentile of the data were used to set threshold levels for training. RESULTS: The results show distinct force patterns for each of the anatomic landmarks. Median Fabs of the navigation task is 3.8 N (1.8-7.3), α is 3.60 (-54-44) and ß is 260 (0-72). CONCLUSION: Unique expert data on navigation forces during wrist arthroscopy were determined. The defined maximum allowable navigation force of 7.3 N (90th percentile) can be used in providing feedback on performance during skills training. The clinical value is that this study contributes to objective assessment of skills levels.

The use of navigation forces for assessment of wrist arthroscopy skills level.

Purpose To provide an efficient learning process, feedback on performance is crucial. In skills laboratories, it is possible to measure the skills and progression of skills of the trainees objectively. This requires metrics that represent the learning curve of the trainee, which were investigated for wrist arthroscopy. The research questions were: What are the forces used by novices during wrist arthroscopy?What aspects of these navigation forces are discriminative for the wrist arthroscopy skills level?Methods A cadaver wrist was mounted in a custom-made distraction device mounted in front of a force platform (ForceTrap). Eleven novices were invited to perform two tasks on the wrist: Insertion of the scope through the 3-4 portal and the hook through the 6R portal, and visualization of the hook in the center of the imageNavigation through the wrist from radial to ulnar with probing and visualization of five predefined landmarksThe second task was repeated 10 times. The absolute force (F abs) and the direction of force were measured. The angle α is defined in the vertical plane, and the angle ß in the horizontal plane. Results The median F abs used by novices remained below the force threshold as defined from the expert data (7.3 N). However, the direction of the applied forces by novices in both planes was not consistent with expert data and showed a wider range. Also, there was no improvement after more trials. Conclusion Our study suggests by the absence of a learning curve for the novices and a significant difference between novices and experts that novices can benefit from feedback on the magnitude and direction of forces to improve their performance.