# Operative time, recurrence, and complications throughout the initial learning curve in transforaminal endoscopic lumbar discectomy

## TL;DR

This study examines the learning curve for a minimally invasive spinal surgery technique called transforaminal endoscopic lumbar discectomy, focusing on how surgical time and outcomes improve with experience.

## Contribution

The study provides a detailed analysis of the initial learning curve for TELD, highlighting the number of cases needed to achieve surgical efficiency.

## Key findings

- Operative time decreased significantly after 50 cases and then stabilized.
- Recurrence and complication rates remained low and did not show significant trends over the learning curve.
- The docking process was identified as the most challenging part of the procedure.

## Abstract

Transforaminal Endoscopic Lumbar Discectomy (TELD) is increasing in popularity as a minimally invasive technique for treating lumbar disc herniation (LDH). However, TELD presents technical challenges that may result in a flat learning curve. This study analysed the first patients treated by a single senior neurosurgeon transitioning from tubular microdiscectomy, focussing on the initial learning curve for operative time, recurrence, and complications.

A retrospective study was conducted using data from a consecutive cohort of the first 213 patients operated for LDH by TELD. We collected basic demographic data and recorded all complications, recurrences, and operative time, among other clinical outcome measures. For analytical purposes (trend testing), the learning curve was divided into four quarters of each approx. 50 patients.

The cohort included 101 (47.4%) females and 112 (52.6%) males, with a mean age of 44.2 ± 11.8 years. An initial steep decrease in operative time after 50 cases performed was observed, decreasing by 21.9 ± 27.7 min (p < 0.001), with operative time showing no further change after those initial 50 cases. Residual LDH was seen in 2 (0.9%) patients. Seventeen (8.0%) patients experienced recurrence of LDH. No statistically significant trend in recurrence rate between quarters was observed (p = 0.99). Complications were experienced by 11 (5.2%) patients, without a significant trend (p = 0.50).

This study demonstrates a clear and steep learning curve for TELD, as shown by a significant decrease in operative time that stabilized after approximately 50 cases. This rapid improvement shows growing familiarity with the technically demanding procedure. In our experience, the initial step of the docking process remains the most challenging aspect, largely due to patient-specific variations. Understanding the initial learning curve is essential for training and surgical planning when transitioning to endoscopic techniques.