Jae Taek Hong

Background/Objectives: Indirect decompression through restoration of disc and foraminal height with a large lateral interbody cage has been advocated for selected patients, but its efficacy in a large series remains unproven. In this retrospective study, we evaluated the clinical and radiographic results of indirect decompression achieved by posterior longitudinal ligament (PLL) ligamentotaxis in minimally invasive oblique lateral interbody fusion (MIS-OLIF) performed without posterior decompression. Methods: We retrospectively reviewed 236 consecutive patients treated for single- or two-level degenerative lumbar disease (November 2019–May 2025); clinical follow-up of at least 24 months was available in 181 patients. Visual analogue scale (VAS) scores and radiographic parameters—disc height, foraminal height, foraminal area, spinal canal diameter and cross-sectional area (CSA) of the thecal sac—were compared before and after surgery, and extension ratios were correlated with preoperative values. Results: Clinical scores improved significantly. All radiographic parameters increased substantially: disc height +49.1%, foraminal height +33.7%, foraminal area +44.5%, canal diameter +37.4% and CSA +36.2%. Extension ratios were inversely correlated with preoperative values. Six patients (2.5%) required additional posterior decompression. The slippage subgroup showed greater radiographic gains than the stenosis subgroup. Conclusions: MIS-OLIF without posterior decompression significantly enlarged the foramen and spinal canal; reduction in disc bulging and PLL ligamentotaxis may contribute to this effect, with greater improvement in more severely degenerated, overtly slipped segments. Careful patient selection remains essential, and prospective comparative studies with longer follow-up are needed.

Background and Objectives: Postoperative dysphagia following anterior cervical discectomy and fusion (ACDF) remains a common complication affecting patient quality of life. This study evaluated the safety and clinical efficacy of reprocessed micronized acellular dermal matrix (ADM) compared to conventional gel-type anti-adhesive agents in patients undergoing single-level ACDF. Materials and Methods: This retrospective propensity score-matched study included 108 patients (54 matched pairs) who underwent single-level ACDF between January 2021 and December 2025. The ADM group received CGDerm Matrix™ and the control group received Mediclore™. The primary outcome was postoperative swallowing function assessed by the Swallowing Impairment Score (SIS-6) at 3 months (pre-specified primary time point). Secondary outcomes included VAS, NDI, modified MacNab criteria, adhesion scores, prevertebral soft tissue swelling, and perioperative inflammatory markers. Bonferroni correction was applied for multiple comparisons (adjusted α = 0.0125). Results: The ADM group demonstrated significantly lower SIS-6 scores at 3 months (0.26 ± 0.16 vs. 0.68 ± 0.27, p = 0.01), which remained significant after Bonferroni correction. All other clinical and radiological outcomes were comparable between groups. No device-related complications occurred. Conclusions: ADM application in ACDF surgery appears safe and is associated with improved postoperative swallowing function at 3 months. However, the clinical significance of observed differences requires further investigation.

Background/Objectives: i-Factor™ Bone Graft is a composite bone substitute containing P-15 synthetic collagen fragment that has demonstrated noninferiority to local autograft in single-level anterior cervical discectomy and fusion (ACDF); however, direct head-to-head comparisons with demineralized bone matrix (DBM) using contemporary 3D-printed titanium cages are lacking. The aim of this retrospective study was to compare radiographic fusion rates, segmental stability, and clinical outcomes between i-Factor™ and DBM in single-level ACDF, with a particular focus on the early time course of fusion. Methods: A retrospective propensity score-matched cohort study was conducted in patients with single-level cervical degenerative disc disease (cervical disc herniation, cervical spondylotic radiculopathy, or cervical spondylotic myelopathy) operated between December 2021 and January 2024 at a single tertiary care hospital. Seventy-six consecutive patients undergoing single-level ACDF with 3D-printed titanium cages were matched 1:1 (i-Factor™ vs. DBM) on age, sex, and operative level. Fusion status was assessed by serial dynamic radiographs at 1, 3, 6, and 12 months and by 3D-CT at 12 months in all patients (with additional CT at earlier timepoints when plain films were equivocal), by two independent spine surgeons blinded to graft type; inter-rater agreement (Cohen’s κ) was computed. Results: Mean follow-up was 18.1 months. Fusion rates for i-Factor™ at 3, 6, and 12 months were 94.7%, 100%, and 100%, respectively, compared to 71.1%, 84.2%, and 94.7% for DBM. The differences were statistically significant at 3 months (p = 0.047) and 6 months (p = 0.012), but not at 12 months (p = 0.493). Inter-rater agreement was almost perfect (κ = 0.86–1.00). No adverse reactions or device-related complications were observed. Conclusions: In this matched cohort, i-Factor™ was associated with significantly faster fusion than DBM in single-level ACDF, with similar 12-month fusion rates. No adverse reactions were observed, although the sample size is insufficient to exclude rare complications.

Endoscopic spine surgery (ESS)—including full-endoscopic transforaminal and interlaminar techniques, and unilateral biportal endoscopy (UBE)—offers patients smaller incisions, preserved paraspinal muscle, and faster recovery. Because the working corridor is narrow, intraoperative fluoroscopy plays a larger role than in open or microscopic approaches, making radiation exposure worthy of attention for both patients and surgeons. This narrative review aims to be a practical resource for the endoscopic spine surgeon. We synthesize the available literature on typical radiation doses across the main ESS techniques, compare them with minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and open alternatives, review the factors that drive exposure, and walk through the full menu of dose-optimization options—from simple measures such as collimation, pulsed fluoroscopy, and leaded eyewear, through navigation platforms, to robotic guidance. A consistent practical observation is that the simplest, least expensive interventions often deliver the largest dose reductions. Capital-intensive technologies add real value, particularly for endoscopic interbody fusion, and work best alongside rather than in place of these basics. With routine dosimetry and straightforward as-low-as-reasonably-achievable (ALARA) practices, surgeons can continue to build on the already favourable profile of ESS while keeping radiation exposure low. Conclusions are tempered by the largely retrospective and heterogeneous nature of the underlying evidence.

Background and Objectives: Minimally invasive cervical spine surgery (MIS-CSS) relies heavily on intraoperative fluoroscopic imaging, raising concerns about radiation exposure to patients and surgical staff. Unlike lumbar MIS, cervical-specific radiation exposure has not been systematically reviewed, despite distinct anatomical considerations, including proximity to the thyroid gland and lens of the eye. This review aims to quantify intraoperative radiation exposure during MIS cervical spine procedures and evaluate available dose-reduction strategies. Materials and Methods: A systematic literature search was conducted across PubMed/MEDLINE, Scopus, and Google Scholar in April 2026 following PRISMA 2020 guidelines. Studies reporting original quantitative radiation data during minimally invasive cervical spine procedures in adult patients (≥10 patients) were included. Quality was assessed using the MINORS tool and the JBI checklist. Results: Seven studies encompassing 380 patients were included. Procedures comprised ACDF (four studies), minimally invasive posterior cervical laminoforaminotomy (two studies), and CT-navigated cervical instrumentation (one study). Patient effective doses during ACDF ranged from 0.015 to 1.3 mSv, with thyroid doses of 0.194–0.290 mGy. Standalone ACDF reduced patient dose by 36–58% compared to plated ACDF (p < 0.001). Navigation-assisted posterior cervical foraminotomy achieved a median fluoroscopy time of 10 s with negligible staff exposure. Surgeon per-procedure exposure during cervical discectomy (chest 0.122 µSv, lens 3.1 µSv, hands 7.1 µSv) was approximately half that of lumbar discectomy. Conclusions: Radiation doses during individual MIS cervical procedures appear to be within occupational safety limits, though the current evidence is insufficient to establish definitive dose thresholds. Standalone implant designs and intraoperative navigation represent effective, complementary dose-reduction strategies. Standardized prospective research is needed to establish cervical-specific radiation safety benchmarks.

Background and Objectives: Minimally invasive cervical spine surgery (MIS-CSS) re-lies heavily on intraoperative fluoroscopic imaging, raising concerns about radiation exposure to patients and surgical staff. Unlike lumbar MIS, cervical-specific radiation exposure has not been systematically reviewed, despite distinct anatomical considera-tions including proximity to the thyroid gland and lens of the eye. This review aims to quantify intraoperative radiation exposure during MIS cervical spine procedures and evaluate available dose-reduction strategies. Materials and Methods: A systematic literature search was conducted across Pub-Med/MEDLINE, Scopus, and Google Scholar in April 2026 following PRISMA 2020 guidelines. Studies reporting original quantitative radiation data during minimally invasive cervical spine procedures in adult patients (≥10 patients) were included. Quality was assessed using the MINORS tool and JBI checklist. Results: Seven studies encompassing 380 patients were included. Procedures com-prised ACDF (four studies), minimally invasive posterior cervical laminoforaminotomy (two studies), and CT-navigated cervical instrumentation (one study). Patient effective doses during ACDF ranged from 0.015 to 1.3 mSv, with thyroid doses of 0.194–0.290 mGy. Standalone ACDF reduced patient dose by 36–58% compared to plated ACDF (p < 0.001). Navigation-assisted posterior cervical foraminotomy achieved a median fluoroscopy time of 10 seconds with negligible staff exposure. Surgeon per-procedure exposure during cervical discectomy (chest 0.122 µSv, lens 3.1 µSv, hands 7.1 µSv) was approximately half that of lumbar discectomy. Conclusions: Radiation doses during individual MIS cervical procedures are generally within occupational safety limits; however, cumulative exposure warrants attention in high-volume surgeons. Standalone implant designs and intraoperative navigation represent effective, complementary dose-reduction strategies. Standardized prospec-tive research is needed to establish cervical-specific radiation safety benchmarks.

Biologically active glasses (BG) are widely studied as potential materials for bone tissue engineering, owing to their capacity to form hydroxyapatite (HA) layers when exposed to body fluids. However, the demerit of BG is the slow deposition rate of calcium ions on the surface, a key factor in increasing the conversion rate to mineralization. The purpose of this study is to introduce phosphoryl group recognized as a trigger for the nucleation processes of apatite formation on the surface of BG. BG was coated with poly (2-methacryloyloxyethyl phosphorylcholine) (PMB) and characterized via Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Biomimetic mineralization was evaluated through simulated body fluid (SBF) immersion, X-ray diffraction (XRD). In vitro MG-63 cell responses were assessed and compared among BG, BG/HA, BG/2%PMB, and BG/2%PMB/HA groups. Results demonstrated that the PMB coating successfully promoted mineralization by introducing negatively charged phosphate groups that enhanced crystallization. BG/2%PMB/HA significantly upregulated focal adhesion markers in MG-63 cells, likely due to improved fibronectin (Fn) deposition on the HA layer. Furthermore, the BG/2%PMB/HA surface enhanced cell survival and proliferation through crosstalk with integrin-mediated signaling pathways. PMB-coated BG effectively accelerates biomimetic mineralization and regulates cellular responses, making it a promising candidate for bone regeneration applications.

Bioactive glass (BG) has emerged as a promising material for bone tissue engineering due to its ability to release osteogenic ions and establish robust interfaces with living tissues, thereby contributing to spinal bone regeneration by facilitating osteointegration and structural stability. Despite these advantageous properties, reconstructing spinal bone defects remains particularly challenging because BG is typically available in powder form, which lacks sufficient mechanical strength and is difficult to handle surgically, especially given the substantial mechanical demands of the spinal column. To overcome these limitations, we employed an injectable, light-curable methacrylated carboxymethyl chitosan (CMCSMA) hydrogel to enable minimally invasive delivery and precise defect filling. Furthermore, to complement BG’s strong osteoconductive capacity with osteoinductive functionality, bone morphogenetic protein-2 (BMP-2) was immobilized onto BG particles (BG/BMP-2), creating a composite scaffold with dual biological activity. The BG/BMP-2/hydrogel system demonstrated sustained BMP-2 release, enhanced osteogenesis, and substantial new bone formation, underscoring the synergy between BG’s bioactive ion release and hydroxyapatite-forming ability. The photocurable hydrogel matrix provided conformal adaptation to defect geometry, potentially improving surgical outcomes. Collectively, this composite represents a promising strategy for minimally invasive and mechanically resilient spinal bone regeneration.

BACKGROUND: Syringomyelia is most often associated with Chiari malformation, for which posterior fossa decompression is the standard treatment. Treatment failure should raise suspicion for alternative mechanisms, particularly in patients with a history of supratentorial craniectomy. In such cases, sinking skin flap syndrome (SSFS) may alter intracranial-extracranial pressure gradients, impair CSF dynamics, and result in an acquired Chiari malformation with secondary syrinx formation. OBSERVATIONS: A 64-year-old man with a remote supratentorial decompressive craniectomy for intracerebral hemorrhage presented with progressive headache, neck pain, and bilateral arm paresthesia. MRI revealed tonsillar herniation with syringomyelia. Posterior fossa decompression led to initial symptom relief and reduction of the syrinx. Three months later, he developed new bilateral leg sensory deficits, and follow-up MRI showed syrinx recurrence despite adequate decompression and no arachnoid adhesions. Because of prior cranioplasty-related infection, he hesitated to undergo further surgery, but ultimately cranioplasty was performed. Postoperatively, symptoms improved, with sustained clinical recovery and syrinx regression confirmed on serial MRI at 12 and 24 months. LESSONS: Persistent or recurrent syringomyelia after Chiari decompression should prompt evaluation for acquired causes. SSFS may mimic primary Chiari malformation; in such cases, cranioplasty can restore CSF dynamics and achieve durable syrinx resolution. https://thejns.org/doi/10.3171/CASE25763