Validity of a Novel Free-Hand Pedicle Screw Placement Training Tool

Validity of A Novel Simulator for Percutaneous Transforaminal Endoscopic Discectomy

BACKGROUND

Percutaneous transforaminal endoscopic discectomy (PTED) has steep learning curves and a high incidence of complications, but currently, efficient and economical training methods are lacking. This study aimed to validate a novel simulator for PTED.

METHODS

The simulated PTED included puncturing and establishing the working channel (PEWC) and endoscopic discectomy, with the PEWC being the tested module. Eleven experts and 21 novices were included and introduced to the simulator and tasks; all participants completed the PEWC. Outcomes included: total operation time, number of fluoroscopy for positioning the working sheath, number of spinal risk region invasion, Global Rating Scale (GRS) and a modified GRS, etc. The Mann-Whitney U test was used to compare 2 groups. Spearman's correlation coefficient analyzed continuous variables.

RESULTS

Experts outperformed novices in total operation time (P = 0.001), requiring fewer number of fluoroscopies for positioning the working sheath (P = 0.003). Additionally, experts had a lower number of spinal risk region invasions (P = 0.016) and higher scores on both the GRS (P < 0.001) and modified GRS (P < 0.001). PTED experience correlated with GRS scores (P = 0.001) and modified GRS (P < 0.001). The overall realism scored a median of 4 (3.75-5), and educational value had a median of 4 (range 3-5).

CONCLUSIONS

This study demonstrates the validity of the novel simulator, revealing significant associations between PTED experience and performance metrics in a simulated PEWC setting. Furthermore, the PEWC module also offers a good realistic design and high education value according to experts.

Validating a Low-Fidelity Model for Microsurgical Anastomosis Training

With cost, size, and availability in mind, we developed a low-fidelity microsurgery anastomosis model for mastery of the tool skills needed to execute microsurgical procedures. The model combined the use of a cannulated Konnyaku Shirataki (KS) noodle with a low-cost, industrial inspection, trinocular stereo (IITS) microscope. The purpose of this study was to establish face and construct validity of this novel "combined" microsurgery training tool.

Methods

Fifteen participants, divided into 3 groups based on microsurgery experience, attempted microsurgical anastomoses of a cannulated KS noodle using the IITS microscope. Participants were asked to (1) manipulate the noodle ends adjacent to each other, (2) place a single 7-0 nylon suture through the opposed ends, and (3) complete the anastomosis. To determine construct validity, the performance of the microsurgical repair (maximum score 53 points) and time-to-anastomosis was assessed. To determine face validity, microsurgeons were given a 25-item, 5-point scale survey rating their experience with the model.

Results

Participants included 5 microsurgeons, 5 experienced trainees, and 5 novices. The microsurgeons judged the IITS microscope to be a close analog to an operating microscope (4.6/5 points), the combined model to have high educational value (4.7/5 points), and somewhat technical similarity with microsurgery in the operating room (OR) (3.7/5 points). The median technical score was 50 among microsurgeons, 40 among experienced trainees, and 27 among novices. Increased training level was associated with greater technical score among all 3 groups (p=0.002). The median time-to-anastomosis was 5.88 minutes for microsurgeons, 8.37 minutes for experienced trainees, and 17.10 minutes for novices. Increased training level was associated with shorter time-to-anastomosis (p=0.003).

Conclusion

The use of the KS noodle with a benchtop stereo microscope is a novel approach to microsurgical training. It is inexpensive, available, conducive to high-repetition training, and suited to many learning environments. Microsurgeons found that this combined model was representative of microsurgery in the OR, and we concluded face validity. Furthermore, an association was demonstrated between training level and performance on the model, suggesting construct validity.

Is the Measurement of Pedicle Axial Axes on Computed Tomography in Adolescent Idiopathic Scoliosis Also a Guide for Safer Screwing?

OBJECTIVE

To evaluate the effect of pedicle angle measurement in preoperative axial computed tomography in patients with adolescent idiopathic scoliosis (AIS) on correct thoracic screw placement in free-hand technique on 3-dimensional printing AIS models.

METHODS

In this study, 14 3-dimensional spine models with a scale of 1:1, including the entire spine of a patient with Lenke type 1 curve, were used. Group 1 included screwing applications with unknown pedicle axial angles, and group 2 included screwing applications with known pedicle axial angles. The number and direction of screws in malposition were recorded. In addition, medial encroachment distances of the screws were classified as 0-4 mm and greater than 4 mm, and lateral encroachment distances were classified as 0-6 mm and greater than 6 mm. Evaluation parameters were compared statistically between the groups.

RESULTS

The number of screws in the correct position in group 1 was lower than that in group 2 (P < 0.05). The medial and lateral malposition rate in group 1 was greater than that in group 2 (P < 0.05). The medial encroachment rate of 4 mm and greater and lateral encroachment rate of 6 mm and greater in group 1 was greater than that in group 2 (P < 0.05). The medial encroachment rate of 0-4 mm and lateral encroachment rate of 0-6 mm were similar between groups 1 and 2 (P > 0.05).

CONCLUSIONS

Measurement of pedicle axial axes of preoperative thoracic vertebrae on computed tomography in patients with AIS offers more reliable screwing in free-hand technique.