OLIF is a minimally invasive lumbar interbody fusion and has been proved an effective treament for degenerative lumbar disease.8−11 Compared with transforaminal lumbar interbody fusion (TLIF) or posterior lumbar interbody fusion (PLIF), OLIF can maximally preserve posterior structures, including ligamentous structures, muscle and facet joints, however, OLIF does not access to spinal canal and the resulting indirect decompression is a drawback and restricts the application of OLIF, expecially for lumbar degenerative disease accompanied by prolapsed disc herniation or severe lumbar spinal stenosis, which are contraindications of OLIF.12,13 For the above situations, surgeons always choose traditional TLIF or PLIF for direct decompression. However, the risk of substantial bleeding, direct neural injury, epidural adhesion, and posterior ligamentous injury are disadvantages of TLIF and PLIF. We recently attempted OLIF combined with PTED for treating lumbar degenerative disease accompanied by prolapsed disc herniation. PTED is an effective minimally invasive surgery and has been well accepted by surgeons and patients in addressing lumbar disc herniation. PTED has multiple advantages, including local anesthesia, less tissue damage, less risk of nerve injury, shorter operative time and faster recovery.18, 19 Our results indicated that OLIF combined with PTED could significantly relieve the low back and leg pain, improve the disabilities of patients with lumbar degenerative disease accompanied by prolapsed disc herniation. Moreover, there were only 3 patients experiencing complications, but they relieved at follow-up visit, which manifested OLIF combined with PTED was safety for properly selected patients.
Some researchers have also evaluated the clinical and radiographic effectiveness of spinal endoscopic discectomy–assisted OLIF.12,13 Heo et al12 had reported OLIF in assistance of endoscopy in same working channel to treat 14 cases of degenerative lumbar disease with lumbar disc herniation. Compared with their technique, though we needed to change patient position intraoperation and an extra incision was made for PTED, our technique also had multiple advantages: Firstly, the indications for spinal endoscopic discectomy–assisted OLIF in their study was only for degenerative lumbar disease with right foraminal or central disc herniation, as patients were set in right lateral postion and working channel is set by left approach. Our technique is able to decompress spinal canal in all directions, decompressive region is enlarged and indications of endoscopic–assisted OLIF are expanded. Secondly, general anesthesia was kept in their whole process and the mean general anesthesia (refer to operation time) was 155.8 ± 45.1 min. While in our technique, the PTED procedure was performed under local anesthesia, and general anesthesia was only carried in OLIF procedure and the mean general anesthesia (refer to operation time) of OLIF was 60.3 ± 22.3 min. Signifcant reduction of general anesthesia time would reduce the perioperative risk especially for the elderly and accelerate rehabilitation postoperation, which is very valuable for the patients. Thirdly, as the patient remained awake in PTED, and favorable feedback of patient for nerve stimulation helped reducing the risk of nerve injury. Lastly, endoscopy had limited view and needed assistance of special surgical instruments with endoscopic discectomy was conducted in channel of OLIF, however, PTED was conducted by intervertebral foramen approach, which was more feasible and familiar to most surgeons. Heo et al12 had reported another advantage in their study was that being able to extend the fusion bed through endoscopic discectomy and explore the endplate through endoscopic visualization, however, the differences in the fusion rate and clinical outcomes between traditional OLIF with spinal endoscopic discectomy–assisted OLIF were unclear and have not been studied. Therefore, further studies are needed to be carried out to investigate these issues.
Though ALIF can also achieved indirect and direct decompression by removing herniated disc under direct version, it has a long learning curve and cause the possibility of significant complications like iliac vessel and peritoneal injury.20,21 Compared with those of TLIF or PLIF procedures, the present study indicated that OLIF combined with PTED could greatly reduced operation time and blood loss, which was in correspondence with conclusions of Heo et al.12 In our experience, the mean duration of PTED was performed only 55.7 ± 13.9 min, and mean blood loss was only 11.7 ± 5.7 ml. No complications associated with PTED were encountered. The risk of lumbar plexus injury is unignorable with lateral lumbar interbody fusion (LLIF). Bergey et al reported that 30% of the patients exhibited paresthesia, thigh pain, and lumbar plexus injury afer surgery using the direct lateral approach.22 The approach of OLIF was performed between the anterior vessels and the psoas muscles, and the occurrence of lumbar plexus injuriy was reduced. In the present study, we found only minor injury or irritation of the lumbar plexus in 2 patients, and these complications were relieved at 1 month follow-up visit.
OLIF combined with PTED have particular advantages, and expand indications of OLIF technique. As PTED working in a new channel and decompressing ventral dura in all directions, it was capable of treating degenerative disease like vertebral posterior osteophytes, and migrated disc herniation and intervertebral disc calcification, while these special situations were limited by Heo’s technique.12 However, special attention should also be paid in our technique. On one hand, to perform OLIF combined with PTED, previous experience with PTED is required. In our patients, additional PTED was performed by an expert endoscopic spine surgeon. On the other hand, OLIF combined with PTED has limitation in decompressing dorsal dura, it may not be eligible for facet joint hypertrophy and ligamentum flavum calcification or ossification.
Nevertheless, several potential study limitations also need to be acknowledged. Firstly, the study was retrospective by design and had a small sample size, however, the incidence of such diseases is relative low. Besides, our technique still required randomized controlled trial with other interbody fusion future. More importantly, for the patients underwent OLIF along with PTED and percutaneous pedicle screw fixation, though these techniques are all minimally invasive, they together may increased operation time. Further randomized studies with a larger sample size and a longer follow-up period are needed to demonstrate this issue.