Learning curve for percutaneous endoscopic lumbar discectomy depending on the surgeon's training level of minimally invasive spine surgery

Abstract

Purpose

To evaluate the differences of learning curve for PELD depending on the surgeon’ s training level of minimally invasive spine surgery.

Methods

We retrospectively reviewed the medical records of 120 patients (surgeon A with his first 60 patients, surgeon B with his first 60 patients) with sciatica and single-level L4/5 disk herniation who underwent PELD by the two surgeons with different training level of minimally invasive spine surgery (Group A: surgeon with little professional training of PELD; Group B: surgeon with 2 years of demonstration teaching of PELD).

Results

Significant differences were observed in the operation time (p = 0.000), postoperative hospital stay (p = 0.026) and reoperation rate (p = 0.050) between the two groups. In the operation time, significant differences were observed between the 1–20 patients group and 41–60 patients group in Group B (p = 0.041), but there were no significant differences among the 1–20 patients group, 21–40 patients group and 41–60 patients group in Group A. In the postoperative hospital stay, the significant differences were observed in the 1–20 patients group between Group A and Group B (p = 0.011). Significant differences were observed between preoperative and postoperative VAS back score, VAS leg score and JOA score. Higher improvement in the VAS leg score was observed in Group B than Group A (p = 0.031). In the rate of reoperation, the significant difference was observed between the 1–20 patients group and 41–60 patients group in Group A (p = 0.028) but there were no significant differences among the 1–20 patients group, 21–40 patients group and 41–60 patients group in Group B.

Conclusions

The surgeons’ training level of minimally invasive spine surgery was an important factor for the success of PELD, especially the demonstration teaching of PELD for the new minimally invasive spine surgeons.

Introduction

An open posterior approach is an effective technique for the surgical treatment of lumbar disk herniation (LDH) [1], [2], [3]. However, open treatment may cause significant muscular injury and later extensive scar formation within the spinal canal. These factors may be considered as primary reasons for post-discectomy syndrome [4], [5], [6]. Minimally invasive techniques have been gradually used in lumbar discectomy surgery to avoid above-mentioned disadvantages. Percutaneous endoscopic lumbar discectomy (PELD) has recently been performed as an alternative to classic open discectomy with results that are comparable to those of open discectomy [7], [8]. PELD is usually performed under local anesthesia, postoperative pain is quite minimal, normal paraspinal structures are preserved, and the risk of postoperative epidural scar formation and instability can be minimized [7], [8], [9], [10].

However, the PELD technique has a “steep” learning curve, which can be overcome with training and suitable patient selection [11]. Lee et al. [12] pointed out that the PELD learning curve is acceptable with relatively low failure and complication rates. Comparison of the early, middle and late experience groups found no significant differences in the factors concerning the learning curve except operating time [12]. The technique is a totally sealed tubular approach. Any surgical manipulation in the technique must be performed using indirect two-dimensional monitor viewing. In addition, hand-eye cooperation with the use of the PELD instrumentations and identification of anatomic structures can also appear daunting. Although other studies have emphasized the precipitous learning curve of minimally invasive lumbar discectomy [12], [13], [14], [15], the study about learning curve of PELD is limited and the learning curve described in the study [11], [12] just simply discuss about the operating time, intraoperative bleeding, complication rate and need for reoperation after PELD failure. In the current study, we systematically evaluated the learning curve of PELD technique according to different surgeon's training level of minimally invasive spine surgery and discussed the important of demonstration teaching for the success of PELD operated by the new minimally invasive spine surgeons.