Special learning curves and clinical outcome of full-endoscopic lumbar interbody fusion

Background In recent years, some researchers have reported the learning curves of TLIF, MIS-TLIF, and OLIF. However, there were few reports about the learning curve of PE-LIF. Methods Data for consecutive patients with single-segment lumbar spondylolisthesis or lumbar spinal stenosis who had undergone PE-LIF with percutaneous pedicle screw fixation from January 2022 to September 2023 were retrospectively collected. We tried to divide the entire surgical process into different time segments according to surgical steps and the learning curves of each time frame were plotted out and further studied. We also reported the initial clinical results to provide experience of the safety, accuracy, and efficiency of PE-LIF directly. Results A total of 42 patients was included in the study, of which 2 patients were lost to follow-up and were excluded from the scope of the study. The duration of the surgery and each corresponding step decreased while the number of cases increased. Yet, the slope of whole operative time and each corresponding step flattened at quite different case numbers. The VAS score in low-back pain, leg pain and ODI score improved significantly for all patients after surgery and continued to improve throughout the entire follow-up. At the 1-year follow-up, excellent modified Macnab outcomes were achieved at 26 patients, good at 13, and fair at 1. The incidence rate of complications in the series was 7.5%: 1 case of cage retropulsion, 1 case of cage subsidence, 1 case of dural matter tear and no intraoperative neurovascular injury. Conclusions It is technically feasible and safe to implant an interbody fusion cage device directly through an endoscopic working cannula. It may be accelerated the process of endplates preparation under the endoscopy by introducing endplate handling equipment used in open surgery.