Navigation forces during wrist arthroscopy: assessment of expert levels

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. 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 alpha being the angle in the vertical plane and beta being the angle in the horizontal plane. The 10th-90th percentile of the data were used to set threshold levels for training. 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), alpha is 3.60 (-54-44) and beta is 260 (0-72). 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.