Physicians in Training Learning Endoscopy: Reduction in Radiation Exposure with Optical Navigation Technology

Background: The endoscopic approach to the spine has a steep learning curve, primarily due to challenges in learning how to access Kambin's triangle, leading to significant radiation exposure. Real-time live instrument tracking using two-dimensional fluoroscopic navigation has been shown to significantly reduce the time and radiation exposure needed to perform a trans-Kambin approach; however, the impact on the learning curve for those in training has not been studied. Methods: Physicians in training (PITs) in a single program were evaluated while accessing Kambin's triangle using a gel sawbone model. The PITs were randomized in terms of spinal level, the technology used first, and the approach side. Time to access Kambin's triangle and radiation were recorded for each cohort. A linear regression model was used to assess associations between procedure time and radiation exposure and endoscopic experience and PGY level. Results: Seven PITs were studied with a range of prior experience, consisting of three PITs with high exposure (HE) (≥30 cases) and four with low exposure (LE) (0-20 cases, averaging 7.5). Unassisted by instrument tracking, the SE group was 63% faster and was exposed to 63% less radiation. Further, there was a moderate correlation with experience and time (R = -0.52) and radiation (R = -0.60). Using instrument tracking allowed all the PITs to be 40% faster, taking 6.6 min (range 2.9-12.4) without instrument tracking and 4.0 min (1.9-6.3) with it. Radiation also decreased by 91% (2.52 vs. 0.23 mGy with instrument tracking). Conclusions: Experience significantly enhanced the accessibility of Kambin's triangle, reducing time and radiation exposure by about two-thirds. Regardless of experience, instrument tracking reduced radiation exposure by 90%. Additionally, familiarizing PITs with instrument location can eliminate 70% of the learning curve for those inexperienced with accessing Kambin's triangle.