Simulation on synthetic bone: A tool for teaching thoracolumbar pedicle screw placement

Study of surgical performance during clavicle plate placements using 2 learning methods: naive practice versus deliberate practice

BACKGROUND

Companionship and simple experience or naive practice (NP) rarely lead to expert level surgery, in contrast to deliberate practice (DP) where an expert analyzes the learner's errors and sets goals to improve performance. The main hypothesis was that using DP for learning would result in faster and/or greater progress than using NP.

OBJECTIVES

The objective of this work was to compare the evolution of the learning curve for clavicle locking plate placement on a sawbone model of a clavicle fracture, by surgical trainees learning via two different methods; NP and DP.

PATIENTS AND METHODS

Ten surgical residents, divided into 2 groups of 5, each placed 6 plates. The 6 trials were filmed. The NP group saw an expert video before each placement. The DP group saw this video once and then received personalized advice from the expert for improvement, by analyzing their own video after each subsequent trial. Objective performance (OP) was measured by a standardized evaluation grid (OSATS, with a score ranging from 10 to 50 points per trial), self-evaluation of performance by a numerical scale (from 0 to 10) and stress by an analgesia-nociception index (ANI, calculated by heart rate recording, from 0 to 100).

RESULTS

The mean OP at the last trial of clavicle plate placement was 41.8 (NP group) and 48.2 (DP group), with a mean progression from the first to last trials of 0.8 in the NP group, and 5.1 in the DP group. The mean progression in self-evaluation between the first and last trials was 3.4 (NP group) and 4.6 (DP group). The mean progression of the ANI between the first and last trials was -4.5 (NP group) and +5 (DP group).

DISCUSSION

The results of learning a clavicle plate osteosynthesis technique measured by OSATS were better with deliberate practice than with naive practice. The progression in self-evaluated performance was better with deliberate practice, but with a higher stress level.

CONCLUSION

Deliberate practice is a technique for learning the surgical procedure which complements companionship and experience. It shortens the learning curve and improves the level of performance of surgical trainees.

LEVEL OF EVIDENCE

IV; non-interventional research.

Biomechanical effects of posterior lumbar interbody fusion with vertical placement of pedicle screws compared to traditional placement

BACKGROUND

The pedicle screw technique is widely employed for vertebral body fixation in the treatment of spinal disorders. However, traditional screw placement methods require the dissection of paraspinal muscles and the insertion of pedicle screws at specific transverse section angles (TSA). Larger TSA angles require more force to pull the muscle tissue, which can increase the risk of surgical trauma and ischemic injury to the lumbar muscles.

AIM

To study the feasibility of zero-degree TSA vertical pedicle screw technique in the lumbosacral segment.

METHODS

Finite element models of vertebral bodies and pedicle screw-rod systems were established for the L4-S1 spinal segments. A standard axial load of 500 N and a rotational torque of 10 N/m were applied. Simulated screw pull-out experiment was conducted to observe pedicle screw resistance to pull-out, maximum stress, load-displacement ratio, maximum stress in vertebral bodies, load-displacement ratio in vertebral bodies, and the stress distribution in pedicle screws and vertebral bodies. Differences between the 0-degree and 17-degree TSA were compared.

RESULTS

At 0-degree TSA, the screw pull-out force decreased by 11.35% compared to that at 17-degree TSA (P < 0.05). At 0-degree and 17-degree TSA, the stress range in the screw-rod system was 335.1-657.5 MPa and 242.8-648.5 MPa, separately, which were below the fracture threshold for the screw-rod system (924 MPa). At 0-degree and 17-degree TSA, the stress range in the vertebral bodies was 68.45-78.91 MPa and 39.08-72.73 MPa, separately, which were below the typical bone yield stress range for vertebral bodies (110-125 MPa). At 0-degree TSA, the load-displacement ratio for the vertebral bodies and pedicle screws was slightly lower compared to that at 17-degree TSA, indicating slightly lower stability (P < 0.05).

CONCLUSION

The safety and stability of 0-degree TSA are slightly lower, but the risks of screw-rod system fracture, vertebral body fracture, and rupture are within acceptable limits.

A Standardized Curriculum Improves Trainee Rod Bending Proficiency in Spinal Deformity Surgery. Results of a Prospective Randomized Controlled Educational Study

INTRODUCTION

Surgical simulation is increasingly being accepted as a training platform to promote skill development and a safe surgical technique. Preliminary investigations in spine surgery show that simulation paired with educational intervention can markedly improve trainee performance. This study used a newly developed thoracolumbar fusion rod bending model to assess the effect of a novel educational curriculum and simulator training on surgical trainee rod bending speed and proficiency.

METHODS

Junior (PGY1 to 2) and senior (PGY3-fellow) surgical trainees at a single academic institution were prospectively enrolled in a rod bending simulation using a T7-pelvis spinal fusion model. Participants completed two simulations, with 1 month between first and second attempts. Fifty percent of surgeons in each training level were randomized to receive an educational curriculum (rod bending technique videos and unlimited simulator practice) between simulation attempts. Rod bending simulation proficiency was determined by the percentage of participants who completed the task (conclusion at 20 minutes), time to task completion or conclusion, and number of incomplete set screws at task conclusion. Participants completed a preparticipation and postparticipation survey. Univariate analysis compared rod bending proficiency and survey results between education and control cohorts.

RESULTS

Forty trainees (20 junior and 20 senior) were enrolled, with 20 participants randomized to the education and control cohorts. No notable differences were observed in the first simulation rod bending proficiency or preparticipation survey results between the education and control cohorts. In the second simulation, the education versus the control cohort demonstrated a significantly higher completion rate ( P = 0.01), shorter task time ( P = 0.009), fewer incomplete screws ( P = 0.003), and greater experience level ( P = 0.008) and comfort level ( P = 0.002) on postparticipation survey.

DISCUSSION

Trainees who participated in a novel educational curriculum and simulator training relative to the control cohort improved markedly in rod bending proficiency and comfort level. Rod bending simulation could be incorporated in existing residency and fellowship surgical skills curricula.

LEVEL OF EVIDENCE

I.

Pedagogy in spine surgery: developing a free and open-access virtual simulator for lumbar pedicle screws placement

PURPOSE

Simulators for pedicle screws placement range from basic sawbones to virtual reality. Yet, they remain expensive and often require specific devices. No free online virtual simulator has yet been developed. The goal was to design a freely accessible Web-based simulator.

METHODS

The computer simulator consisted of a lumbar spine, a red box hiding the pedicles and five pairs of screws. After inserting the screws, the red box was removed to assess their position. A validation study was conducted with 24 medical students randomized into a simulation and a control group. All had a basic course on pedicle screws. The 12 simulation group students performed two sessions on computer. All 24 students then conducted a final common step on sawbones. The number of misplaced screws, types of breaches, and simulation times were analyzed.

RESULTS

In the final sawbones simulation, 96 real screws were studied. Control group misplaced 50% of their screws compared with only 20.8% in the simulation group (p < 0.05). More careful, simulation group students were slower to insert their real screws. Over the two computer simulations, the rate of misplaced screws decreased (12.5% vs. 38.3%), showing a good handling of the simulator. Students were able to analyze and correct their pedicle breaches.

CONCLUSION

This tool is the first free online lumbar pedicle screws simulator. Simulation helped students to better position the final real screws on sawbones. This project showed it was possible to create a free educational tool with no special equipment.

LEVEL OF EVIDENCE

Level 3.