Use of a High-Fidelity Training Simulator for Minimally Invasive Lumbar Decompression Increases Working Knowledge and Technical Skills Among Orthopedic and Neurosurgical Trainees

Abstract

Study design: Prospective comparative study.

Objective: To quantify the educational benefit to surgical trainees of using a high-fidelity simulator to perform minimally invasive (MIS) unilateral laminotomy for bilateral decompression (ULBD) for lumbar stenosis.

Methods: Twelve orthopedic and neurologic surgery residents performed three MIS ULBD procedures over 2 weeks on a simulator guided by established AO Spine metrics. Video recording of each surgery was rated by three blinded, independent experts using a global rating scale. The learning curve was evaluated with attention to technical skills, skipped steps, occurrence of errors, and timing. A knowledge gap analysis evaluating participants' current vs desired ability was performed after each trial.

Results: From trial 1 to 3, there was a decrease in average procedural time by 31.7 minutes. The cumulative number of skipped steps and surgical errors decreased from 25 to 6 and 24 to 6, respectively. Overall surgical proficiency improved as indicated by video rating of efficiency and smoothness of surgical maneuvers, most notably with knowledge and handling of instruments. The greatest changes were noted in junior rather than senior residents. Average knowledge gap analysis significantly decreased by 30% from the first to last trial (P = .001), signifying trainees performed closer to their desired technical goal.

Conclusion: Procedural metrics for minimally invasive ULBD in combination with a realistic surgical simulator can be used to improve the skills and confidence of trainees. Surgical simulation may offer an important educational complement to traditional methods of skill acquisition and should be explored further with other MIS techniques.

Keywords: laminectomy; lumbar; minimally invasive; model; simulation; simulator; unilateral laminotomy for bilateral decompression.

Figure 1.

Schematic and intraoperative views from the high-fidelity surgical simulator depicting examples of key procedural steps as defined in the AO consensus guidelines for unilateral laminectomy for bilateral decompression (ULBD). (A) Starting point depicting the inferior edge of the superior level lamina and ligamentum flavum interface prior to drilling. (B) Exposure of the ipsilateral ligamentum flavum up to the insertion after hemilaminotomy. (C) “Airplaning” the table and angling the retractor medially to view the contralateral lamina in preparation for the over-the-top drilling. (D) Contralateral ligamentum visualization following contralateral laminotomy in preparation for flavectomy.

Figure 2.

High-fidelity lumbar stenosis surgical simulator. (A) Sagittal and (B) axial T2-weight MRI of a patient with high-grade lumbar stenosis at the L4/5 level due to a combination of disc bulge, facet arthropathy, and ligamentum flavum hypertrophy. The anatomical features of this MRI were used to develop the lumbar stenosis model. Trainees are able to review imaging prior to the operative trials. (C) Photograph of a surgical trainee performing ULBD on the complete simulator (Real Spine, Realists Training Technologies GmbH, Leipzig, Germany) with external housing consisting of skin and subdermal layers to create a more realistic simulation of operating on a human lumbar spine. (D) This simulator consists of a core base (skin cover removed in this picture) with power system and space for bags of simulated blood and cerebrospinal fluid (CSF) which can be manually controlled (for more bleeding or higher-pressure CSF flow). (E) Intraoperative microscopic view of the trainee performing the decompression while managing epidural and bony bleeding.

Figure 3.

Decrease in mean (A) procedure duration, (B) total skipped steps, and (C) errors over the course of successive trials. While the differences between trials 1 and 2 were mild to moderate, there was substantial improvement in all 3 areas when comparing the first and third trials.

Figure 4.

Surgical proficiency from first and third trials based on the eight skill domains from the Global Rating Scale. There was improvement in every category, with greatest improvement seen with knowledge of instruments, instrument handling, and overall surgical proficiency.

Figure 5.

The overall knowledge gap of all participants significantly decreased in the third surgical trial compared to the first trial. Knowledge gap = (current skill level/desired skill level)*100. Two tailed P-value was calculated via Wilcoxon matched-pairs signed rank test. *** indicates P = .001.