Background
Minimally invasive transpsoas or antepsoas lateral lumbar interbody fusion (MI-LLIF) has been reported as an effective surgical option for various lumbar diseases. Many researchers reported high fusion rate and clinical excellence of LLIF with the use of bone morphogenic protein (BMP). However, there have been paucity of studies regarding LLIF without the use of BMP. Therefore, this study aimed to analyze radiologic and clinical results of patients who underwent minimally invasive lateral lumbar interbody fusion without the use of BMP. Furthermore, a further analysis was conducted regarding the frequency of cage subsidence and its impact on the radiologic and clinical outcome.
Materials and Methods
Fifty patients and 109 levels treated by MI-LLIF with postoperative follow-up of at least 2 years were included. Radiologic evaluation included intervertebral disc height, segmental lordosis, lumbar lordosis, fusion rate, cage subsidence grade, and the bone mineral density. Radiologic fusion was determined by modified Bridwell’s grade, and cage subsidence by Marchi’s grade. Clinical outcome was evaluated by VAS of low back pain (LBP) and leg pain, and ODI score. The above clinical and radiologic variables were analyzed statistically for comparison of cage subsidence and nonsubsidence groups.
Results
There were 20 male and 30 female patients with the average age of 69 years. Average follow-up period was 29.6 months(24-42 months). Graft material used for PEEK cage was autogenous bone only in 9 levels, autogenous bone and DBM in 19 levels, and DBM only in 81 levels. Twelve patients received surgery on 1 level, 20 patients on 2 levels, 17 patients on 3 levels, and 1 patient on 4 levels, respectively. Operated levels were L1-2 in 7 cases, L2-3 in 27, L3-4 in 41, and L4-5 in 34, respectively. Mean low back pain (LBP) VAS decreased from preoperative 5.5 to 2.2 at the final follow-up, leg pain from 6.1 to 1.7, and ODI score from 25.6 to 13.7, with statistical significance (p<0.001). Mean disc height increased from preoperative 5.9 mm to postoperative 11.5 mm, and subsequently decreased to 9.6mm at the final follow-up. Average lumbar lordosis increased from preoperative 18.6 degrees to postoperative 37.0 degrees, and 35.9 degree at final follow-up. Radiologic union rate was 90.8%. Cage subsidence was observed in 6 levels (5.5%) on immediate postoperative radiographs; and in 20 levels (18.3%) at final follow-up. Comparison between cage subsidence and non-subsidence groups revealed no significant difference in age and BMD. Immediate postoperative segmental lordosis was considered as a risk factor of cage subsidence (p=0.005, odds ratio 0.813, CI 0.703~0.940). Furthermore, the preoperative and the final follow-up measurement of disc height, VAS score of LBP and leg pain, and ODI score were not different between the two groups. However, pseudoarthrosis rate was higher in subsidence group.
Conclusions
Minimally invasive LLIF was an effective surgical option with high fusion rate even without the use of BMP. Although cage subsidence also increases the frequency of pseudarthrosis, it does not significantly deteriorate the lumbar lordosis correction and clinical outcome.

Purpose
To evaluate the impacts of regional and socioeconomic factors on adolescent idiopathic scoliosis (AIS) diagnosis and treatment using national datasets of the Korean National Health Insurance System. The prevalence of, and therapeutic trends in, AIS are affected by a variety of environmental factors.
Materials and Methods
We analyzed random samples from datasets (10% of all entries) between 2012 and 2018, including in terms of patient demographics, residential status (a “special city”, and urban, and rural regions) and socioeconomic status (SES) based on health insurance premiums (which distinguish National Health Insurance and Medical Aid [MA] beneficiaries).
Results
The AIS prevalence was approximately 1.6-fold higher in females than in males, whereas the rate of male surgery was approximately 1.5-fold higher than that in females. AIS prevalence was higher among National Health Insurance beneficiaries (in all years), whereas the surgery rate was higher among MA beneficiaries (in most years). In all years, AIS prevalence was significantly higher among special city residents than in urban and rural residents. However, the surgical treatment rates were higher in the latter regions.
Conclusions
Our nationwide evaluation revealed AIS prevalence rates and therapeutic trends. AIS epidemiology varies by region and economic status.

Purpose
To evaluate whether the contralateral radiating pain improved after unilateral decompression and minimally invasive transforaminal lumbar interbody fusion (TLIF) in the patients with bilateral radiating pain due to degenerative lumbar disease.
Materials and Methods
Patients with the degenerative lumbar disease who underwent unilateral minimally invasive TLIF and were followed for more than 1 year were included. Clinically, low back pain and radiating pain on the dominant symptom side and the contralateral side were evaluated by the visual analogue score (VAS), and the Oswestry disability index (ODI) score was also evaluated.
Results
ODI and VAS of low back pain and radiating pain were effectively reduced in a total of 57 cases. Thirty cases having bilateral radiating pain, among these patients, unilateral decompression was performed in 15 cases and bilateral decompression thru unilateral approach in 15 patients. In unilateral decompression group, radiating pain on the dominant symptom side, and radiating pain on the contralateral side were also improved at the final followup. In 15 cases who underwent bilateral decompression, radiating pain on the dominant symptom side and the contralateral side were improved at the final follow-up. There was no significant difference between the two groups in terms of preoperative ODI, VAS of low back and radiating pain.
Conclusions
Minimally invasive TLIF via unilateral approach with or without contralateral decompression showed good clinical results in patients having unilateral or bilateral radiating pain. Minimally invasive TLIF could be an useful option even if there is bilateral radiating pain in degenerative lumbar disease.

Purpose
Spinal fusion is useful method of treatment of degenerative lumbar diseases, and is divided into anterior and posterior surgery. Each approach has advangages and disadvantages. Recently, minimally invasive lateral lumbar interbody fusion (LLIF) supplemented disadvantages of anterior and posterior surgery is interested. We introduce LLIF and present about application and indication of LLIF.
Materials and Methods
A 76-year-old female was diagnosed by degenerative disc disease on L2-3. A 66-year-old male was diagnosed by central spinal stenosis on L2-3-4-5. A 86-year-old female was diagnosed by foraminal stenosis on L3-4-5 and degenerative scoliosis. A 73-year-old male was diagnosed by spinal stenosis on L3-4-5 and spondylolisthesis. A 70-year-old male was diagnosed nonunion on L4-5. On past history, the patient was operated by fusion because of L2 burst fracture. A 75-year-old female was diagnosed by infective spondylodiscitis on L3-4.
Results
Degenerative disc disease, severe central and foraminal spinal stenosis, degenerative scoliosis, spondylolisthesis and infective spondylodiscitis were application and indication of LLIF.
Conclusions
LLIF merges the advantages and covers the disadvantages of anterior and posterior surgery. However, approach-related lumbar plexus injury and L5-S1 approach were remained obstacles.