Background
The Selective thoracic fusion (STF) may be associated with risk of postoperative coronal decompensation, lumbar decompensation and adding-on phenomenon, which can lead to persistence of the lumbar curve and consequently to deviation of the trunk. Therefore, the STF is the most debatable issue as the optimal surgical correction in adolescent idiopathic scoliosis with Lenke 1C curves.
Methods
A total of 30 patients with adolescent idiopathic scoliosis with Lenke 1C curves who underwent STF between 1996 and 2017 were included. Minimum follow-up duration was five years. We analyzed the incidence of coronal decompensation, lumbar decompensation, distal adding-on phenomenon and trunk shift in these patients for radiographic adverse event. Clinical outcome was assessed by using the Scoliosis Research Society (SRS)-22r scores.
Results
The mean age at the time of surgery was 13.8±2.9 years. The mean follow-up duration was 80.4±12.3 months. The Cobb’s angle for main thoracic curve improved by 59.6% (p<0.001), and also The Cobb’s angle for thoracolumbar/ lumbar curve improved by 40.5% comparing preoperative and postoperative values (p<0.001). There was significant improvement in the Cobb’s angle for main thoracic and Thoracolumbar/lumbar curve comparing preoperative and last follow-up values (p<0.001). At last follow-up, the coronal balance was 10.3 ± 9.1 that significant improved from the immediate postoperative value (p=0.033). The incidence of coronal decompensation, lumbar decompensation, adding-on and trunk shift in our cohort was 16.7%, 10.0%, 13.3% and 10.0% respectively. The average SRS score at last follow-up in patients with radiographic adverse events was 4.3±0.5. That of patients without adverse events was 4.4±0.6. All domains between patients with and without adverse events had no statistical significance difference.
Conclusions
Selective thoracic fusion in Lenke 1C curves have acceptable risk of coronal decompensation, lumbar decompensation, distal adding-on, trunk shift. However, no revision surgery was required in these patients after long term follow-up. Therefore, STF in Lenke 1C curves seems to be enough.

Background
It is well reported that the patient’s age plays an important role associated with proximal junctional failure (PJF) development. Various characteristics of adult spinal deformity (ASD) patients were different between younger and older age groups. We hypothesized that the radiographic risk factors for PJF would different according to younger and older age groups. This study aimed to evaluate different radiographic risk factor of PJF according to the two age groups undergoing thoracolumbar fusion for ASD.
Methods
ASD patients aged ≥ 60 years who underwent thoracolumbar fusion from low thoracic level (T9~T12) to sacrum were included. The minimum follow-up duration was two years. PJF was defined as proximal junctional angle (PJA) ≥ 20°, fixation failure, fracture, myelopathy, or necessity of revision surgery. Using various radiographic risk factors including age-adjusted ideal pelvic incidence (PI)-lumbar lordosis (LL), univariate and multivariate analyses were performed separately according to the two age groups : <70 years and ≥70 years.
Results
A total of 186 patients were enrolled (mean age=68.5 years old, 90.3% female). Mean follow-up duration was 67.4 months. PJF developed in 98 patients (32.0%). There were fracture in 53 patients, PJA ≥ 20° in 26, fixation failure in 12, and myelopathy in 6. PJF developed more frequently in patients older than 70 years than in younger than 70 years. In patients aged less than 70 years, preoperative LL, PI-LL and change in LL were significant risk factors in univariate analysis. Multivariate analysis showed only change in LL was significant for PJF development (Odds ratio [OR]=1.025, p=0.021). On the other hand, in patients older than 70 years, postoperative LL, postoperative PILL, overcorrection relative to conventional PI-LL target (within ±10°) as well as age-adjusted ideal PI-LL target were significant. On multivariate analysis, only overcorrection of PI-LL relative to age-adjusted ideal target was a single significant factor to cause PJF (OR=5.250, p=0.024).
Conclusions
In patients younger than 70 years, greater change in LL was associated with PJF development regardless of PI-related value. However, in older patients, overcorrection of PI-LL relative to the age-adjusted PI-LL target was important to cause PJF.

Background
When obese patients underwent lumbar discectomy using a microscope, a correlation was found between the operation time and an increase in estimated blood loss according to the increase in body mass index. However, except for minor complications, there was no difference in postoperative outcomes between obese and normal-weight patients. These are the results of microscopic lumbar discectomy in obese patients, but there are no studies on biportal endoscopic lumbar discectomy. The aim of this study was to compare the clinical and radiographic outcomes of microscopic and endoscopic discectomy in obese patients.
Methods
Clinical and radiological data were compared and analyzed in 23 obese patients with a body mass index of >30 kg/m² who underwent microscopic and biportal endoscopic lumbar discectomy. Clinical data on the visual analog scale (VAS), Oswestry Disability Index (ODI), and EuroQol-5D (EQ-5D) scores were measured, and radiological data were measured using magnetic resonance imaging (MRI).
Results
In total, 13 patients who underwent microscopic discectomy and 10 who underwent biportal endoscopic discectomy were enrolled in this study. The VAS, ODI, and EQ-5D scores in both groups improved after surgery compared with those before surgery, although there was no difference between the two groups. Although there was a difference in the incidence of recurrent disc herniation confirmed by MRI after surgery, there was no difference in the number of patients requiring surgery between the two groups.
Conclusions
There were no significant clinical or radiological differences in outcomes between microscopic and biportal endoscopic surgery methods.

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.