A Systematic Review of Complications Associated with Initial Learning Curve of Endoscopic Spine Surgery Highlighting the Necessity of Introducing an Effective Fellowship to Train Competent Endoscopic Spine Surgeons

Pang Hung Wu^1,2*, Hyeun Sung Kim¹, Dong Hwa Heo¹, Gamaliel Yu Heng Tan¹ and Tae Jang^1
*Correspondence: Pang Hung Wu, Department of Spine, Nanoori Gangnam Hospital, Seoul Spine Surgery, Korea, Email:

Keywords

Endoscopic spine surgery • Endoscopy • Surgery education • Training program in surgery • Complications in endoscopic spine surgery • Learning curve in endoscopic spine surgery

Abbreviations

TELD: Transforaminal Endoscopic Lumbar Discectomy; TELF: Transforaminal Lumbar Foraminotomy; TE-LRD: Transforaminal Endoscopic Lateral Recess Decompression; IELD: Interlaminar Endoscopic Lumbar Discectomy; IE-LRD: Interlaminar Endoscopic Lateral Recess Decompression; LE-ULBD: Lumbar Endoscopic Unilateral Laminotomy for Bilateral Decompression; EELD: Extraforaminal Endoscopic Lumbar Discectomy; ICELF: Interlaminar Contralateral Endoscopic Lumbar Foraminotomy; PECF: Posterior Cervical Endoscopy Foraminotomy; PECD: Posterior Endoscopic Cervical Discectomy; AECD: Anterior Endoscopic Cervical Discectomy; TETD: Transforaminal Endoscopic Thoracic Discectomy; TE-ULBD: Throacic Endoscopic Unilateral Laminotomy for Bilateral Decompression

Introduction

With the evolution of endoscopic spine surgery as an option in minimally invasive surgery, there is an increasing number of endoscopic spine procedures performed to treat various spinal conditions. The steep learning curve was one of the reasons for the low overall pick up rate of endoscopic spine surgery among spine surgeons. There is paucity of literature to evaluate the initial complication rate during the early phase of learning curve of endoscopic spine surgery. The experts who practise uniportal and/or biportal endoscopic spine surgery from various centres around the world had set up fellowship program to fulfil the training requirements of budding endoscopic spine surgeon to mitigate these complication risks in early phase of endoscopic practice. Our objective in this review is to evaluate the most consistent parameters of the learning curve which were procedure time and complication rate. We also discussed the importance of endoscopic spine surgery fellowship. We propose various educational strategies and highlight the difficulties encountered by mentors and fellows in the process of gaining knowledge and skills in endoscopic spine surgery.

Literature Review

Search strategy and criteria

We used the Cochrane methodology [1] to perform a systematic review of PubMed for the learning curve of endoscopic spine surgery. We used three successive searches: “Endoscopic Spine Surgery” (4221 results), “AND complications” (reduced to 2301 articles), “AND learning curve” (reduced to 101 articles). A manual review of abstracts of 101 articles was performed. 85 articles did not describe procedures which used spinal endoscope and were excluded. 16 articles were reviewed in full, 6 articles which were describing techniques of tubular retractor with microendoscopic assisted decompression were excluded. 10 articles met the criteria of uniportal and biportal endoscopic surgeries evaluation of complications and operation timing in the initial learning curve were included in our systematic review [2-11]. None of the articles were case report (Table 1). The mean and median publication year was 2016. We included four Transforaminal Endoscopic Lumbar Decompression/Discectomy (TELD) studies, two Biportal Endoscopic Spine Surgery (BESS) studies, three Interlaminar Endoscopic Lumbar Discectomy (IELD) studies, one mixed TELD and IELD study in this review. No cervical or thoracic endoscopic spine procedures describing learning curve was found in our review. Of the 618 spinal endoscopic procedures included in this review, all were level IV evidence case series evaluating a retrospective cohort of patients operated at different time point of the performing surgeons (Figure 1).

Endoscopic learning curve parameters assessed were complication rate and operating time. In the 10 studies, total number of complications were 45 cases (7.2%) of which 33 cases (5.3%) occurred in the early phase of learning curve and 12 cases (1.9%) occurred at the later phase of learning curve. The most frequent reported complications were incomplete decompression (18 cases, 2.9%), incidental durotomies (13 cases; 2.1%), nerve root injuries (11 cases; 1.77%), discitis (2 cases; 0.32% of complications) and hematoma (1 case; 0.16%). 9 early revisions were reported of which 5 were done for dural tears, 4 were for incomplete decompression. 7 late revisions were done for recurrence of disc herniations. Joswig et al. [5] had a disproportionally high intraoperative conversion rate of 16/76 (21%) most of which were due to technical difficulties, while Passacantilli et al. [2] had 3/100 (3%) conversion due to technical difficulties. Various length of duration of procedures was reported as shown in Table 1. Due to heterogeneity of the 10 studies involved, we were unable to identify a conclusive number of cases needed to achieve asymptote for the learning curve. The operative time was observed to decrease throughout these case series prior to reaching asymptote with less variation in timing once asymptote of learning curve was reached.

Conclusion

There is a trend of higher complication and longer operation time during early phase of learning curve in endoscopic spine surgery. Good guidance from fellowship mentor is recommended to overcome the steep learning curve. It is evident that the differences in outcome can be significant between proficient and inexperienced surgeons. We suggest a stepwise approach in progression in delivery of progressively more challenging endoscopic procedures during the fellowship. This stepwise acquisition of knowledge and skills can be achieved structured teaching in simulation trainings, cadaveric workshop, live surgeries and various assessment tools moderated by the endoscopic mentors. Despite the allure of endoscopic surgery, it is important for the fellows to be competent with open procedures in order to resolve complications arising from endoscopic spine surgery with open conversion and manage challenging cases which required open surgical intervention.

Acknowledgement

Dr. Hyeun-Sung Kim and Dr. Pang Hung Wu contributed equally to this work as first authors. We would like to acknowledge scientific team members Ms. Jae Eun Park, Ms Elin Lee and Mr. Kyeong Rae Kim for providing assistance in statistical support, acquiring full text articles and managing digital works.

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