Variation in joint stressing magnitudes during knee arthroscopy

Force measurement metrics for simulated elbow arthroscopy training

Background

Elbow arthroscopy is a difficult surgical technique. Objective metrics can be used to improve safe and effective training in elbow arthroscopy. Force exerted on the elbow tissue during arthroscopy can be a measure of safe tissue manipulation. The purpose of this study was to determine the force magnitude and force direction used by experts during arthroscopic elbow navigation in cadaveric specimens and assess their applicability in elbow arthroscopy training.

Methods

Two cadaveric elbows were mounted on a Force Measurement Table (FMT) that allowed 3-dimensional measurements (x-, y-, and z-plane) of the forces exerted on the elbow. Five experts in elbow arthroscopy performed arthroscopic navigation once in each of two cadaveric elbows, navigating through the posterior, posterolateral and anterior compartment in a standardized fashion with visualization of three to four anatomic landmarks per compartment. The total absolute force (F_abs) and force direction exerted (α and β) on the elbow during arthroscopy were recorded. α being the angle in the horizontal plane and β being the angle in the vertical plane. The 10th–90th percentiles of the data were used to set threshold levels for training.

Results

The median F_abs was 24 N (19 N – 30 N), 27 N (20 N – 33 N) and 29 N (23 N – 32 N) for the posterior, posterolateral and anterior compartment, respectively. The median α was - 29° (- 55° – 5°), - 23° (- 56° – -1°) and 4° (- 22° – -18°) for the posterior, posterolateral and anterior compartment, respectively. The median β was - 71° (- 80° – -65°), - 76° (- 86° – -69°) and - 75° (- 81° – -71°) for the posterior, posterolateral and anterior compartment, respectively.

Conclusion

Expert data on force magnitude and force direction exerted on the elbow during arthroscopic navigation in cadaveric specimens were collected. The proposed maximum allowable force of 30 N (smallest 90th percentile of F_abs) exerted on the elbow tissue, and the 10th–90th percentile range of the force directions (α and β) for each compartment may be used to provide objective feedback during arthroscopic skills training.

A Force Measurement System for Training of Arthroscopic Tissue Manipulation Skills on Cadaveric Specimen

To improve arthroscopic skills, the preferred means of training is cadaveric tissue, because this gives the most realistic scenario. A drawback of cadaveric training is that objective performance tracking and accompanied feedback cannot be provided due to the absence of a suitable system. The main criteria were that the system should be compatible with any cadaveric joint, be used with any type of instrument, easy to set up, and measure two critical parameters that reflect the task efficiency (task time) and safety (forces due to instrument–tissue interaction). This resulted in the development of a force measurement system which consists of a custom-made universal vice, a custom-designed six degree-of-freedom (DOF) force measurement table (FMT) coupled to a computer equipped with customized software to record the time and forces in all directions. The FMT was calibrated and able to measure forces in the range of 0–750 N, with an accuracy of 0.1 N. During two cadaveric training courses, measurements were performed with the FMT. It was observed that the acquired force data could discriminate between novices and experts or reflect a certain phase of a navigation task performed in a cadaveric cow and human knee. A distinct phase highlighted from the force measurements is the insufficient joint stressing of novices during navigation. This results in too small a joint space for inspection and forces the novices to readjust the stressing. As forces cannot be seen, the FMT can contribute to more efficient training by providing explicit cues on the exerted loads during training. This enables a more precise supervision of the trainees.

Validation of the PASSPORT V2 training environment for arthroscopic skills

PURPOSE

Virtual reality simulators used in the education of orthopaedic residents often lack realistic haptic feedback. To solve this, the (Practice Arthroscopic Surgical Skills for Perfect Operative Real-life Treatment) PASSPORT simulator was developed, which was subjected to fundamental changes: improved realism and user interface. The purpose was to demonstrate its face and construct validity.

METHODS

Thirty-one participants were divided into three groups having different levels of arthroscopic experience. Participants answered questions regarding general information and the outer appearance of the simulator for face validity. Construct validity was assessed with one standardized navigation task, which was timed. Face validity, educational value and user-friendliness were determined with two representative exercises and by asking participants to fill out the questionnaire. A value of 7 or greater was considered sufficient.

RESULTS

Construct validity was demonstrated between experts and novices. Median task time for the fifth trial was 55 s (range 17-139 s) for the novices, 33 s (range 17-59 s) for the intermediates, and 26 s (range 14-52 s) for the experts. Median task times of three trials were not significantly different between the novices and intermediates, and none of the trials between intermediates and experts. Face validity, educational value and user-friendliness were perceived as sufficient (median >7). The presence of realistic tactile feedback was considered the biggest asset of the simulator.

CONCLUSION

Proper preparation for arthroscopic operations will increase the quality of real-life surgery and patients' safety. The PASSPORT simulator can assist in achieving this, as it showed construct and face validity, and its physical nature offered adequate haptic feedback during training. This indicates that PASSPORT has potential to evolve as a valuable training modality.