Over the past few decades, interest in minimally invasive spine surgery (MISS) has increased tremendously due to its core principle of minimizing approach-related injury while providing outcomes similar to traditional open spine procedures. With technical and technological advancements, MISS has expanded its utility not only to simple spinal stenosis, but also to complex spinal pathologies such as metastasis, trauma, or adult spinal deformity. In this article, we review the techniques and technology in MISS and discuss the indications, benefits, and limitations of MISS.

BACKGROUND: Vitamin C has critical features relavant to postoperative pain management and functional improvement; however, no study has yet evaluated the effectiveness of vitamin C on improving the surgical outcomes for spine pathologies. Thus, this study aimed to explore the impact of vitamin C on postoperative outcomes after single-level posterior lumbar interbody fusion (PLIF) for lumbar spinal stenosis in prospectively randomized design. We conducted a 1-year prospective, randomized, placebo-controlled, double-blind study to evaluate the impact of vitamin C on the postoperative outcomes after PLIF surgery. METHODS: A total of 123 eligible patients were randomly assigned to either group A (62 patients with vitamin C) or group B (61 patients with placebo). Patient follow-up was continued for at least 1 year after surgery. The primary outcome measure was pain intensity in the lower back using a visual analogue scale. The secondary outcome measures were: (1) the clinical outcome assessed using the Oswestry Disability Index (ODI); (2) the fusion rate assessed using dynamic radiographs and computed tomography scans; and (3) complications. RESULTS: Pain intensity in the lower back was significantly improved in both groups compared with preoperative pain intensity, but no significant difference was observed between the 2 groups over the follow-up period. The ODI score of group A at the third postoperative month was significantly higher than the score of group B. After the sixth postoperative month, the ODI score of group A was slightly higher than the score of group B; however, this difference was not significant. The fusion rates at 1 year after surgery and the complication rates were not significantly different between the 2 groups. CONCLUSIONS: Postoperative pain intensity, the primary outcome measure, was not significantly different at 1 year after surgery between the 2 groups. However, vitamin C may be associated with improving functional status after PLIF surgery, especially during the first 3 postoperative months.
Ascorbic Acid* ; Double-Blind Method ; Follow-Up Studies ; Humans ; Outcome Assessment (Health Care) ; Pain, Postoperative ; Pathology ; Prospective Studies ; Spinal Stenosis ; Spine ; Treatment Outcome ; Vitamins*

BACKGROUND AND PURPOSE: Preexisting cognitive impairment is the strongest risk factor for delirium. We performed a pilot study to investigate whether the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE), which is a good complement to direct cognitive testing, could be useful for predicting postoperative delirium in elderly patients. METHODS: Between June 2013 and May 2014, 37 patients aged 70 years or older underwent the Korean version of the Mini-Mental State Examination (K-MMSE) and completed the IQCODE (IQCODE-K) before elective spine surgery in the Spine Center at the Seoul National University Bundang Hospital. Delirium was assessed daily from the day after surgery until discharge. A Mann-Whitney U test was used to compare the K-MMSE scores and the IQCODE-K scores between the groups with and without postoperative delirium. RESULTS: A total of three of 37 (8.1%) patients developed delirium during their hospital stay. The K-MMSE scores were not different between the two groups (p=0.105), whereas the IQCODE-K scores of patients with delirium were significantly higher than those of patients without delirium (p=0.021), indicating greater cognitive and functional decline over the previous 10 years. CONCLUSION: The IQCODE may be a suitable tool for assessing preoperative cognitive function and predicting postoperative delirium in elderly patients.
Aged* ; Cognition ; Complement System Proteins ; Delirium* ; Humans ; Length of Stay ; Pilot Projects* ; Risk Factors ; Seoul ; Spine

STUDY DESIGN: Review article. OBJECTIVES: To present the latest knowledge on spine surgery using augmented reality (AR). SUMMARY OF LITERATURE REVIEW: AR is a new technology that simulates interactions with real-world surroundings using computer graphics, and it is a field that has recently been highlighted as part of the fourth industrial revolution. MATERIALS AND METHODS: Review of related literature and introduction of latest research. RESULTS: Spine surgery using AR is currently in its early stages. If industry, academia, and research institutes cooperate and develop, spine surgery using AR is highly likely to develop to the next level. CONCLUSIONS: Spine surgeons should strive to develop relevant technology.
Academies and Institutes ; Computer Graphics ; Spine ; Surgeons

OBJECTIVES: To present the latest knowledge on spine surgery using augmented reality (AR).SUMMARY OF LITERATURE REVIEW: AR is a new technology that simulates interactions with real-world surroundings using computer graphics, and it is a field that has recently been highlighted as part of the fourth industrial revolution. MATERIALS AND METHODS: Review of related literature and introduction of latest research. RESULTS: Spine surgery using AR is currently in its early stages. If industry, academia, and research institutes cooperate and develop, spine surgery using AR is highly likely to develop to the next level. CONCLUSIONS Spine surgeons should strive to develop relevant technology.

STUDY DESIGN: Prospective randomized noninferiority trial. PURPOSE: To evaluate whether the union rate of anterior cervical discectomy and fusion (ACDF) using a polyetheretherketone (PEEK) cage filled with a mixture of hydroxyapatite (HA) and demineralized bone matrix (DBM) is inferior to that of a mixture of beta-tricalcium phosphate (beta-TCP) and HA. OVERVIEW OF LITERATURE: There have been no clinical trials investigating the outcomes of a mixture of HA and DBM in a PEEK cage in ACDF. METHODS: Eighty-five eligible patients were randomly assigned to group B (n=43), in which a PEEK cage with a mixture of HA and DBM was used, or group C (n=42), in which a PEEK cage with a mixture of HA and beta-TCP was used. The primary study endpoint was the fusion rate, which was assessed with dynamic radiographs and computed tomography (CT) scans. Secondary endpoints included pain intensity using a visual analogue scale, functional outcome using a neck disability index score, laboratory tests of inflammatory profiles, and the infection rate. RESULTS: Seventy-seven patients (38 in group B and 39 in group C) were included in the final analysis. One year postoperatively, bone fusion was achieved in 87% of group B patients and 87% of group C patients on dynamic radiographs, and 87% of group B patients and 72% of group C patients on CT scans (p=1.00 and 0.16, respectively). There were also no between-groups differences with respect to the secondary endpoints. CONCLUSIONS: A HA/DBM mixture inside a PEEK cage can provide noninferior outcomes compared to a HA/TCP mixture in ACDF.
Bone Matrix* ; Diskectomy* ; Durapatite ; Humans ; Hydroxyapatites ; Neck ; Prospective Studies* ; Tomography, X-Ray Computed

PURPOSE: The purpose of this study was to investigate the effects of unilateral pedicle screw fixation on the fusion segment and the superior adjacent segment after one segment lumbar fusion using validated finite element models. MATERIALS AND METHODS: Four L3-4 fusion models were simulated according to the extent of decompression and the method of pedicle screws fixation in L3-4 lumbar fusion. These models included hemi-laminectomy with bilateral pedicle screw fixation in the L3-4 segment (BF-HL model), total laminectomy with bilateral pedicle screw fixation (BF-TL model), hemi-laminectomy with unilateral pedicle screw fixation (UF-HL model), and total laminectomy with unilateral pedicle screw fixation (UF-TL model). In each scenario, intradiscal pressures, annulus stress, and range of motion at the L2-3 and L3-4 segments were analyzed under flexion, extension, lateral bending, and torsional moments. RESULTS: Under four pure moments, the unilateral fixation leads to a reduction in increment of range of motion at the adjacent segment, but larger motions were noted at the fusion segment (L3-4) in the unilateral fixation (UF-HL and UF-TL) models when compared to bilateral fixation. The maximal von Mises stress showed similar patterns to range of motion at both superior adjacent L2-3 segments and fusion segment. CONCLUSION: The current study suggests that unilateral pedicle screw fixation seems to be unable to afford sufficient biomechanical stability in case of bilateral total laminectomy. Conversely, in the case of hemi-laminectomy, unilateral fixation could be an alternative option, which also has potential benefit to reduce the stress of the adjacent segment.
Biomechanical Phenomena ; *Computer Simulation ; Humans ; Lumbar Vertebrae/surgery ; Male ; Middle Aged ; *Models, Anatomic ; *Pedicle Screws ; *Range of Motion, Articular ; Software ; Spinal Fusion ; Stress, Mechanical

BACKGROUND: The authors analyzed inter- and intra-observer agreement with respect to interpretation of simple magnetic resonance T1- and T2-weighted axial and sagittal images for the diagnosis of lumbar lateral disc herniation, including foraminal and extraforaminal disc herniations. METHODS: Forty-two patients in whom lumbar lateral disc herniation was suspected or confirmed by simple magnetic resonance imaging at one institute between May 2003 and December 2004 were included. The magnetic resonance images consisting of T1- and T2-weighted axial and sagittal images, and these were reviewed blindly and independently by three orthopaedic spine surgeons in a random manner. The images were interpreted as positive or negative for lateral disc herniation on 2 different occasions 3 months apart. Results were analyzed using Cohen's kappa statistic, and strengths of agreements were determined using the Landis and Koch criteria. RESULTS: The kappa values for inter-observer agreement averaged 0.234 (0.282, 0.111, and 0.308 respectively) on the first occasion, and 0.166 (0.249, 0.111, and 0.137 respectively) on the second occasion, with an overall mean value of 0.200. Thus, the strength of agreement was only slight-to-fair according to the Landis and Koch criteria. Kappa values for intra-observer agreement averaged 0.479 (0.488, 0.491, and 0.459 respectively), indicating moderate agreement. CONCLUSIONS: The present study indicates that simple magnetic resonance imaging is not a reliable imaging modality for diagnosing lumbar lateral disc herniation. Another imaging study with improved diagnostic values should be developed to diagnose this pathologic finding.
Aged ; Aged, 80 and over ; Female ; Humans ; Intervertebral Disk Displacement/*pathology ; Lumbar Vertebrae/*pathology ; *Magnetic Resonance Imaging ; Male ; Middle Aged ; Observer Variation ; Single-Blind Method

STUDY DESIGN: Retrospective interventional study. PURPOSE: To introduce a free-hand pedicle screw (PS) insertion technique without fluoroscopic guidance in the C7 vertebra and evaluate the procedure's feasibility and radiologic outcomes. OVERVIEW OF LITERATURE: Although PS insertion at C7 has been recognized as a critical procedure in posterior cervical fusion surgery, conventional techniques for C7 PS have several limitations. METHODS: Thirty two patients (64 screws) who underwent PS insertion in C7 with the novel technique were included in this study. Postoperative clinical and radiological outcomes were evaluated. Special attention was paid to the presence of any problems in the screw position including cortical breaches of the PS and encroachment of the PS into the spinal canal or the vertebral foramen. This novel technique for PS insertion in C7 without fluoroscopy guidance had three key elements. First, the ideal PS entry point was chosen near the C6-7 facet joint using preoperative images. Second, the convergent angle distance was measured at axial computed tomography (CT) imaging, which defined the distance between the tip of C7 spinous process and the extended line passing through the pedicle axis from the ideal entry point. Third, the cranial-caudal angle distance was measured in sagittal CT images, which defined the distance between the tip of the C7 spinous process and the extended line passing through the pedicle axis. RESULTS: Cortical breach on postoperative CT images was observed in three screws. All violated only the lateral wall of the affected pedicle. The breached screws occurred in the initial five cases. Postoperative neurologic deterioration was not observed in any patient, regardless of cortical breaching. CONCLUSIONS: The novel technique successfully allows for C7 PS to be placed and is associated with a low rate of cortical breach.
Axis, Cervical Vertebra ; Feasibility Studies* ; Fluoroscopy ; Humans ; Retrospective Studies ; Spinal Canal ; Spine ; Zygapophyseal Joint

PURPOSE: The purpose of this study was to evaluate and compare the biomechanical behavior of the lumbar spine after posterior decompression with the spinous process osteotomy (SPiO) technique or the conventional laminectomy (CL) technique using a finite element (FE) model. MATERIALS AND METHODS: Three validated lumbar FE models (L2-5) which represented intact spine and two decompression models using SPiO and CL techniques at the L3-4 segment were developed. In each model, the ranges of motion, the maximal von Mises stress of the annulus fibrosus, and the intradiscal pressures at the index segment (L3-4) and adjacent segments (L2-3 and L4-5) under 7.5 Nm moments were analyzed. Facet contact forces were also compared among three models under the extension and torsion moments. RESULTS: Compared to the intact model, the CL and SPiO models had increased range of motion and annulus stress at both the index segment (L3-4) and the adjacent segments under flexion and torsion. However, the SPiO model demonstrated a reduced range of motion and annulus stress than the CL model. Both CL and SPiO models had an increase of facet contact force at the L3-4 segment under the torsion moment compared to that of the intact model. Under the extension moment, however, three models demonstrated a similar facet contact force even at the L3-4 model. CONCLUSION: Both decompression methods lead to postoperative segmental instability compared to the intact model. However, SPiO technique leads to better segmental stability compared to the CL technique.
Biomechanical Phenomena ; Decompression, Surgical/*methods ; *Finite Element Analysis ; Humans ; Intervertebral Disc/physiopathology/surgery ; Laminectomy/*methods ; Lumbar Vertebrae/pathology/physiopathology/*surgery ; Male ; Middle Aged ; Models, Anatomic ; Osteotomy/*methods ; Range of Motion, Articular ; Stress, Mechanical ; Zygapophyseal Joint/pathology/physiopathology/surgery