This study showed that PED and OLIF had similar therapeutic effects for LSS. However, PED was superior to OLIF in relieving patients with low back pain and improving function, which implied that direct decompression was better than indirect decompression. But the magnitude of the between-group difference was small. Because it was reported that the surgical effect decreased over time . In complication and reoperation rates, there were no statistical difference between the PED and OLIF group.
Conventional laminectomy decompression is a common surgical method for LSS [29, 30]. The posterior column structure was severely damaged during laminectomy and related facet joint resection, and postoperative complications such as lumbar instability can occur [31, 32]. Lumbar interbody fusion is a common method for the treatment of LSS, which can prevent lumbar spine instability . OLIF is commonly used approach . It is required to resect of joint and soft-tissue structures for conventional decompression of LSS. It is possible to achieve decompression without destroying these structures with the help of endoscopic technology [34, 35]. However, there were few studies to assess endoscopic surgery and OLIF for LSS. Therefore, we conducted this study to compare outcomes after PED and OLIF surgery.
OLIF as an indirect neural decompression had a satisfactory clinical outcome for degenerative spine disease [19, 27, 36]. The current study had similar results with previous studies. But PED was with lower VAS (lumbar) and ODI. This might be because direct decompression is more thorough and endoscopic decompression was with less damage to soft tissues and better recovery. And compared with the PED group, the OLIF group was with longer operation time and hospital stay, more blood loss and more cost. This was consistent with previous studies [21, 37]. OLIF was conducted through the window between abdominal major vessels and anterior border of the psoas muscle , which was reported in 2012 . Silvestre et al. showed that only 7 patients (3.9%) had complications related to lumbar plexus injury or psoas muscle weakness, and all those patients recovered completely after a period of time . There was no patient with complications related to the major vessel injury in our study, which was consistent with previous study . In current study, 2 patients (3.8%) were with intraoperative complications (1 with thigh numbness and 1with hematoncus).The patient with hematoncus received surgery. 3 patients (5.9%) were with postoperative complications. Two patients were with poor fusion and one patient was with cage subsidence who received posterior instrumentation in OLIF group.
Due to the revolutionary advances in technology and equipment, the model of percutaneous endoscopic spinal surgery is shifting from the treatment of disc herniation to the treatment of lumbar spinal stenosis . In current study, 1 patients (2.4%) received second surgery. And there was one patient (2.4%) with dural tear which was sutured with satisfactory result. Bao et al. showed that two patients (3.6%) treated by PED needed a second surgery . The PED group was with lower complications rate at 2.4% than that in the OLIF group. The reduction of operation time, blood loss and operation-related complications in the PED group can also be found in comparisons of the literature related to discectomies [41, 42]. The physical components of SF-36 has been proven to be an effective, responsive and reliable tool for assessing degenerative lumbar spine conditions . The results showed similar outcomes in SF-36. The hospitalization cost of lumbar fusion surgery is higher, which may indicate that the comprehensive value assessment may be more inclined to perform decompression surgery alone .
So far, there is still much controversy about the indications of decompression plus fusion. Some experts have pointed out that patients with predominantly leg symptoms and no signs of segmental instability and deformities should use stability-preserving decompression techniques to avoid fusion . Our study revealed that patients who were with or without mild degenerative spondylolisthesis all achieved satisfactory results in the PED group. This results were consistent with previous studies [4, 44]
There were some limitations in this study. First of all, this was a retrospective study. The follow-up period was relatively short and the sample size was small which was unable to evaluate the long-term difference in efficacy and safety between the two groups. Finally, the diameter of the spinal canal was not measured. The efficacy of surgery will be evaluated by measuring the postoperative diameter of the spinal canal in future research.
In conclusion, PED and OLIF had satisfactory results for LSS. In general, PED was superior to OLIF in relieving patients with low back pain and improving function without any obvious shortcomings. Therefore, we recommend PED for LSS. However, further studies are needed to evaluate the long-term maintenance of the efficacy of PED surgery. There is an urgent need to identify indications that decompression requires additional fusion. Future economic analyses may include the loss of productivity, reoperations, and the use of outpatient health resources to compare these surgical methods over a longer period of time.