Minimally invasive surgery had the advantage of minimal trauma and rapid recovery. Open lumbar surgery for the treatment of lumbar degenerative diseases was effective, but slow recovery rates and postoperative complications remained a concern. Studies also indicated that open PLIF, TLIF, or the removal of the nucleus pulposus by posterior fenestration of vertebral plate lead to injury of the paraspinal muscles [16, 17]. Some patients may suffer post-surgical low back pain. Percutaneous spinal endoscopic surgery can complete the removal of the nucleus pulposus under local anesthesia through the intervertebral foramen or the interlaminar approach with short operation time, lower blood loss and mild soft tissue injury [9, 18]. Numerous studies have confirmed the curative and reliable efficacy of PELD [9, 10, 12]. A meta-analysis showed that the average postoperative recurrence rates of PELD in the treatment of lumbar disc herniation were 3.6%. Old age, obesity, upper lumbar disc herniation, and central disc herniation were risk factors for disease recurrence [19]. Percutaneous endoscopic discectomy and interbody fusion (PEDIF) was not commonly used during surgery due to controversy regarding their clinical efficacy [20]. The fusion rate was low and the curative effect was not good, which was often related to the incomplete curettage of the upper and lower endplates of the intervertebral space and the small amount of bone graft [20]. LLIF was performed through the retroperitoneal space to the lateral intervertebral space. The intervertebral space was completely treated using minimally invasive methods. A large number of bone grafts are employed, leading to high intervertebral fusion rates. In addition, indirect spinal decompression is achieved. Large disc herniation, herniated nucleus pulposus, and extreme lateral herniation were contraindications to LLIF. Lumbar endoscopic surgery acted on decompression and LLIF focused on fusion. The combination of the two minimally invasive surgeries could correct the deficits of each individual procedure. The combination of LLIF and PELD for the treatment of lumbar degenerative diseases has not been widely reported. The aim of this study was to evaluate the clinical efficacy and safety of this combined and minimally invasive technique for the treatment of lumbar low-grade spondylolisthesis.
A total of 48 patients were included in the case series and LLIF under general anesthesia followed by lumbar endoscopic surgery under local anesthesia was performed. The average operation time of the combination surgery was 116.35min ± 22.31, and the average blood loss was 112.60ml ± 43.69. In previous meta-analysis comparing PLIF to TLIF, the mean PLIF time was 150–182 min and the blood loss was 245–994 ml; the operative time for TLIF was 105–165 min and the blood loss was 215–867 ml [21]. The total operation time and blood loss of the combined surgery were thus lower. The small incision size, decompression by endoscopy and intraoperative radiofrequency electrocoagulation for hemostasis were key reasons for lower blood loss. In addition, LLIF was performed from the retroperitoneal space which was distant from the blood vessels leading to minimal blood loss. The VAS and ODI of the case series at 3, 6, 12 months post-surgery, and the last follow-up were significantly lower than those before surgery, suggesting good clinical efficacy. Previous studies have concentrated on the clinical efficacy of single minimally invasive surgery. Furthermore, lumbar endoscopic surgery and LLIF for the treatment of lumbar degenerative diseases for a range of indications are reliable [22, 23]. The combination of minimally invasive surgery could achieve direct decompression and interbody fusion, covering shortfalls of each single minimally invasive procedure. Assessment of intervertebral fusion rates using CT in previous studies showed that the rate of intervertebral fusion at 1-year post-retroperitoneal anterolateral interbody fusion was approximately 85–97% [24–26]. The fusion rate at the latest follow-up of patients in this study was 93.7% and thus similar. The combined minimally invasive surgery demonstrated a high degree of operational safety. A single patient experienced severe upper endplate injury, and two patients had postoperative left anterior thigh numbness and pain combined with psoas muscle weakness. Some patient factors may lead to intraoperative endplate injury, including osteoporosis, stenosis of the intervertebral space, a high sacral ridge, and obesity. In addition, less experience in the initial procedures, excessive use of the sharp reamer, and the wrong direction of curettage of intervertebral disc could also result in intraoperative endplate injury [27]. Endplate injury could cause endplate collapse, cage subsidence, and/or displacement during follow-up. Timely posterior internal fixation to strengthen intervertebral stability could reduce postoperative cage subsidence and displacement [5, 28]. The patient with endplate injury in this study was supplemented with internal fixation and there was no obvious cage subsidence during the follow-up period. Intervertebral fusion was good at the last follow-up. The patients had postoperative left anterior thigh numbness and pain combined with psoas muscle weakness, caused by the excessive involvement of lumbar plexus during LLIF splitting psoas major muscle. The symptoms disappeared on the 5th post-surgical day. With improved technology, the safety of lumbar endoscopic surgery was gradually increasing. Surgeon should operate gently and carefully in order to avoid dura and nerve injury.
In this study, a combined minimally invasive technique that combined lumbar endoscopic surgery with LLIF for the treatment of lumbar degenerative diseases was proposed. Due to rapid developments in lumbar endoscopic techniques, the technical obstacles for the adequate decompression of various types of disc herniation were overcome. Endoscopic technique was characterized by flexibility, minimally invasive and direct decompression. Lateral fusion using LLIF achieved exact and robust intervertebral fusion with no disruption to the posterior lumbar muscles, ligaments, and bony structures [26]. Combination of two minimally invasive techniques can be used to overcome complex lumbar problems. Similarly, we envisaged the possibility of combining lateral lumbar fusion technology with MED or microscopic lumbar decompression surgery to provide a beautiful “combination blow” according to the actual situation of patients with lumbar diseases.
There were some limitations in this study. The sample size was small and further enlargement of sample size will be needed to make the conclusion more convincing. This was a retrospective case series study and the internal fixation method was not unified in advance. The type of internal fixation may influence VAS and ODI, which was the limitation of the retrospective study. In future studies, we will unify internal fixation standard. This study was also a single-center case series and no control group was established. In future studies, we will compare this combination of minimally invasive techniques with the traditional open surgery of lumbar posterior approach to further demonstrate its superiority. Cases included in this study only involved single-segment surgery. The clinical efficacy of the combination of minimally invasive surgery for double-segment lumbar surgery requires further analysis.