Unilateral Biportal Endoscopy for Decompression of Extraforaminal Stenosis at the Lumbosacral Junction: Surgical Techniques and Clinical Outcomes.

OBJECTIVE: The aims of this study were to describe the unilateral biportal endoscopic (UBE) technique for decompression of extraforaminal stenosis at L5-S1 and evaluate 1-year clinical outcomes. Especially, we evaluated compression factors of extraforaminal stenosis at L5-S1 and described the surgical technique for decompression in detail. METHODS: Thirty-five patients who underwent UBE decompression for extraforaminal stenosis at L5-S1 between March 2018 and February 2019 were enrolled. Clinical results were analyzed using the MacNab criteria, the visual analogue scale (VAS) for back and leg pain, and the Oswestry Disability Index (ODI). Compression factors evaluated pseudoarthrosis within the transverse process of L5 and ala of sacrum, disc bulging with or without osteophytes, and the thickened lumbosacral and extraforaminal ligament. RESULTS: The mean back VAS was 3.7 ± 1.8 before surgery, which dropped to 2.3 ± 0.8 at 1-year postoperative follow-up (p < 0.001). There was a significant drop in postoperative mean VAS for leg pain from 7.2 ± 1.1 to 2.3 ± 1.2 at 1 year (p < 0.001). The ODI was 61.5 before surgery and 28.6 (p < 0.001). Pseudoarthrosis between the transverse process and the ala was noted in all cases (35 of 35, 100%). Pure disc bulging was seen in 12 patients (34.3%), and disc bulging with osteophytes was demonstrated in 23 patients. The thickened lumbosacral and extraforaminal ligament were identified in 19 cases (51.4%). No complications occurred in any of the patients. CONCLUSION: In the current study, good surgical outcomes without complications were achieved after UBE decompression for extraforaminal stenosis at L5-S1.

Correction to: Clinical and radiological outcomes of unilateral biportal endoscopic lumbar interbody fusion (ULIF) compared with conventional posterior lumbar interbody fusion (PLIF): 1-year follow-up.

The original publication of this article has incorrect presentation of one of the author names. Instead of Sangu-Kyu Son, it should have been Sang-Kyu Son.

Clinical and radiological outcomes of unilateral biportal endoscopic lumbar interbody fusion (ULIF) compared with conventional posterior lumbar interbody fusion (PLIF): 1-year follow-up.

This study retrospectively compared clinical and radiological outcomes of unilateral biportal endoscopic lumbar interbody fusion (ULIF) to those of conventional posterior lumbar interbody fusion (PLIF). Seventy-one ULIF (age, 68 ± 8 years) and 70 PLIF (66 ± 9 years) patients for one lumbosacral segment followed more than 1 year were selected. Parameters for surgical techniques (operation time, whether transfused), clinical results [visual analogue scale (VAS) for back and leg pain, Oswestry disability index (ODI)], surgical complications (dural tear, nerve root injury, infection), and radiological results (cage subsidence, screw loosening, fusion) between the two groups were compared. The PLIF group demonstrated a significantly shorter operation time and more transfusions done than the ULIF group. The VAS for leg pain in both groups and for back pain in the ULIF group significantly improved at 1 week, while the VAS for back pain in the PLIF group significantly improved at 1 year. ODI scores improved at 1 year in both groups. Complication rates were not significantly different between groups. Fusion rates with definite and probable grades were not significantly different between groups. However, the ULIF group had significantly (P = 0.013) fewer cases of definite fusion and more cases of probable fusion [43 (74.1%) and 15 (25.9%) cases, respectively] than the PLIF group [58 (92.1%) and 5 (7.9%) cases, respectively]. ULIF is less invasive while just as effective as conventional PLIF in improving clinical outcomes and obtaining fusion. However, ULIF has a longer operation time than PLIF and requires further development to improve the fusion grade.

Decreased osteogenic differentiation of mesenchymal stem cells and reduced bone mineral density in patients with adolescent idiopathic scoliosis.

Generalized low bone mass and osteopenia in both axial and peripheral skeletons have been reported in adolescent idiopathic scoliosis (AIS). However, the mechanism and causes of bone loss in AIS have not been identified. Therefore, this study examined the relationship between the osteogenic and adipogenic differentiation abilities of mesenchymal stem cells (MSCs) and bone mass in 19 patients with AIS and compared these with those of 16 age- and gender-matched patients with lower leg fracture. Mean lumbar spinal bone mineral density (LSBMD) in AIS patients was found to be lower than in controls (P = 0.037) and the osteogenic differentiation abilities and alkaline phosphatase activities of MSCs from patients were also found to be lower than those of controls (P = 0.0073 and P = 0.001, respectively), but the abilities of the MSCs of patients and controls to undergo adipogenic differentiation were similar. The osteogenic differentiation ability was found to be positively correlated with alkaline phosphatase activity in the AIS group. However, the osteogenic and adipogenic abilities were not found to be correlated with LSBMD in either patients or controls. These findings suggest that the decreased osteogenic differentiation ability of MSCs might be one of the possible mechanisms leading to low bone mass in AIS. However, we did not determine definite mechanisms of low bone mass in AIS. Therefore, further study with large scale will be needed to identify the mechanism involved.

Association between osteoprotegerin gene polymorphism and bone mineral density in patients with adolescent idiopathic scoliosis.

Generalized low bone mass and osteopenia have been reported in the axial and peripheral skeleton of adolescent idiopathic scoliosis (AIS) patients. Recently, many studies have shown that gene polymorphisms are related to osteoporosis. However, no studies have linked the association between gene polymorphisms and bone mass of AIS. Therefore, this study examined the association between the bone mass and RANKL, RANK, and OPG gene polymorphisms in 198 girls diagnosed with AIS. OPG 163 A --> G, 209 G --> A, 245 T --> G, and 1181 G --> C polymorphisms; RANK 421 C --> T and 575 C --> T polymorphisms; and RANKL rs12721445 and rs2277438 polymorphisms, as well as the bone mineral density at the lumbar spine (LSBMD) and femoral neck (FNBMD) were analyzed. The 163 A --> G, 209 G --> A, and 245 T --> G polymorphisms in the OPG gene were in complete linkage. No RANK 421 C --> T and 575 C --> T polymorphisms or RANKL rs12711445 polymorphism were observed. There was a significant association between the OPG gene 1181 G --> C polymorphism and LSBMD. LSBMD in AIS with the CC genotype was found to be significantly higher than in AIS with the GC (P < 0.05) or GG (P < 0.01) genotype. However, there was no significant association between LSBMD or FNBMD and the OPG gene 245 T --> G polymorphism or the RANKL rs2277438 polymorphism. These results suggest that the OPG gene 1181 G --> C polymorphism is associated with LSBMD in girls with AIS.

Cerebral glucose metabolic abnormality in patients with congenital scoliosis.

A possible association between congenital scoliosis and low mental status has been recognized, but there are no reports describing the mental status or cerebral metabolism in patients with congenital scoliosis in detail. We investigated the mental status using a mini-mental status exam as well as the cerebral glucose metabolism using F-18 fluorodeoxyglucose brain positron emission tomography in 12 patients with congenital scoliosis and compared them with those of 14 age-matched patients with adolescent idiopathic scoliosis. The mean mini-mental status exam score in the congenital scoliosis group was significantly lower than that in the adolescent idiopathic scoliosis group. Group analysis found that various brain areas of patients with congenital scoliosis showed glucose hypometabolisms in the left prefrontal cortex (Brodmann area 10), right orbitofrontal cortex (Brodmann area 11), left dorsolateral prefrontal cortex (Brodmann area 9), left anterior cingulate gyrus (Brodmann area 24) and pulvinar of the left thalamus. From this study, we could find the metabolic abnormalities of brain in patients with congenital scoliosis and suggest the possible role of voxel-based analysis of brain fluorodeoxyglucose positron emission tomography.