Bum Joon Kim

Customized Cranioplasty Implants Using Three-Dimensional Printers and Polymethyl-Methacrylate Casting

Objective The prefabrication of customized cranioplastic implants has been introduced to overcome the difficulties of intra-operative implant molding. The authors present a new technique, which consists of the prefabrication of implant molds using three-dimensional (3D) printers and polymethyl-methacrylate (PMMA) casting. Methods A total of 16 patients with large skull defects (>100 cm2) underwent cranioplasty between November 2009 and April 2011. For unilateral cranial defects, 3D images of the skull were obtained from preoperative axial 1-mm spiral computed tomography (CT) scans. The image of the implant was generated by a digital subtraction mirror-imaging process using the normal side of the cranium as a model. For bilateral cranial defects, precraniectomy routine spiral CT scan data were merged with postcraniectomy 3D CT images following a smoothing process. Prefabrication of the mold was performed by the 3D printer. Intraoperatively, the PMMA implant was created with the prefabricated mold, and fit into the cranial defect. Results The median operation time was 184.36±26.07 minutes. Postoperative CT scans showed excellent restoration of the symmetrical contours and curvature of the cranium in all cases. The median follow-up period was 23 months (range, 14-28 months). Postoperative infection was developed in one case (6.2%) who had an open wound defect previously. Conclusion Customized cranioplasty PMMA implants using 3D printer may be a useful technique for the reconstruction of various cranial defects.

Risk factors of delayed surgical evacuation for initially nonoperative acute subdural hematomas following mild head injury

BackgroundAlthough the majority of patients with minimal acute subdural hematomas (aSDHs) can be managed conservatively, some require delayed aSDH evacuation due to hematoma enlargement. This study was designed to determine the risk factors associated with delayed hematoma enlargement leading to surgery in patients with aSDHs who did not initially require surgical intervention.MethodsFrom 2002 to 2012, 98 patients were treated for nonoperative aSDHs following mild head injury (Glasgow Coma Scale scores of 13–15). The outcome variables were radiographic evidence of SDH enlargement on serially obtained computed tomography (CT) images and later surgical evacuation. Univariate and multivariate analyses were applied to both the demographic and initial radiographic features to identify risk factors for SDH progression and surgery.ResultsOverall, 64 patients (65xa0%) revealed minimal SDH or spontaneous hematoma resolution (conservative group) with conservative management at their last follow-up CT scan. The remaining 34 patients (35xa0%) received delayed hematoma evacuation (delayed surgery group) a median of 17xa0days after the head trauma. There were no significant differences between the two groups for baseline characteristics, including age, injury type, degree of brain atrophy, prior history of antithrombotic drugs, and coagulopathy. The presence of cerebral contusions and subarachnoid hemorrhages was more common in the conservative group (pu2009=u20090.003 and pu2009=u20090.003, respectively). On multivariate analysis, hematoma volume (pu2009=u20090.01, odds ratio [OR]u2009=u20091.094, 95xa0% confidence interval [CI]u2009=u20091.021–1.173) and degree of midline shift (pu2009=u20090.01, ORu2009=u20091.433, 95xa0% CIu2009=u20091.088–1.888) on the initial CT scan were independently associated with delayed hematoma evacuation.ConclusionsA critical proportion of patients with minimal aSDHs occurring after mild head injury can progress over several weeks and require hematoma evacuation. Especially patients with a large initial SDH volume and accompanying midline shift require careful monitoring of hematoma progression.

The Mechanism of Ligamentum Flavum Hypertrophy: Introducing Angiogenesis as a Critical Link That Couples Mechanical Stress and Hypertrophy.

BACKGROUNDnBiochemical alterations associated with mechanical stress have been explored as an initiating step in the pathological progression of ligamentum flavum hypertrophy (LFH); however, this mechanism remains poorly understood. Recently, the inflammation induced after mechanical stress and the subsequent response of ligamentum flavum (LF) cells have been implicated in LFH pathology.nnnOBJECTIVEnTo investigate the hypothesis that angiogenesis may be a critical link between hypertrophy and a series of stimulating events, including mechanical stress.nnnMETHODSnLF from 20 lumbar spinal canal stenosis (LSCS) patients and 16 non-LSCS patients (control group) were collected during surgery. Patient demographic and radiographic data were obtained. The levels of angiogenic factors (vascular endothelial growth factor [VEGF], angiopoietin-1, vascular cell adhesion molecule, and basic fibroblast growth factor) in the LF were investigated by using an enzyme-linked immunosorbent assay. Angiogenesis was also quantified by immunohistochemical detection of CD34-positive capillaries. The correlations among clinical factors, including radiographic factors, angiogenic factors, and angiogenesis, were statistically analyzed.nnnRESULTSnThe LSCS group was older and exhibited a longer symptom duration, wider segmental motion, and thicker LF than the control group. The LSCS group showed significantly higher tissue concentrations of VEGF (P < .001) that positively correlated with LF thickness (r = 0.557, P < .001) and segmental motion (r = 0.586, P < .001). The LSCS group showed significantly more CD34-positive capillaries than the control group (P = .004).nnnCONCLUSIONnThe LSCS group showed greater segmental motion, higher VEGF concentrations, and more CD34-positive capillaries than the control group. These data indicate that VEGF-mediated angiogenesis following mechanical stress may be a critical step within the series of pathological events in LFH.

Modified Open-door Laminoplasty Using Hydroxyapatite Spacers and Miniplates

Objective Cervical laminoplasty has been widely accepted as one of the major treatments for cervical myelopathy and various modifications and supplementary procedures have been devised to achieve both proper decompression and stability of the cervical spine. We present the retrospectively analyzed results of a modified unilateral open-door laminoplasty using hydroxyapatite (HA) spacers and malleable titanium miniplates. Methods From June 2008 to May 2012, among patients diagnosed with cervical spondylotic myelopathy and ossification of posterior longitudinal ligament, the patients who received laminoplasty were reviewed. Clinical outcome was assessed using Frankel grade and Japanese Orthopaedic Association score. The radiologic parameters were obtained from plain films, 3-dimensional computed tomography and magnetic resonance images. Results A total of 125 cervical laminae were operated in 38 patients. 11 patients received 4-level laminoplasty and 27 patients received 3-level laminoplasty. Postoperatively, the mean Frankel grade and JOA score were significantly improved from 3.97 to 4.55 and from 12.76 to 14.63, respectively (p<0.001). Radiologically, cervical curvature was worsened from 19.09 to 15.60 (p=0.025). The percentage of range of motion preservation was 73.32±22.39%. The axial dimension of the operated spinal canal was increased from 1.75 to 2.70 cm2 (p<0.001). Conclusion In the presenting study, unilateral open-door laminoplasty using HA spacers and miniplates appears to be a safe, rapid and easy procedure to obtain an immediate and rigid stabilization of the posterior elements of the cervical spine. This modified laminoplasty method showed effective expansion of the spinal canal and favorable clinical outcomes.

Comparison of subgroups based on hemorrhagic lesions between SWI and FLAIR in pediatric traumatic brain injury

PurposeThe purpose of this study was to investigate efficient ways to diagnose and predict clinical outcomes for childhood traumatic brain injury.MethodsHemorrhagic signal intensities in nine brain regions were observed using axial fluid-attenuated inversion recovery (FLAIR) and susceptibility-weighted imaging (SWI). After having divided the subjects into mild presentation (GCS 14–15) and moderate-to-severe presentation groups (GCS ≤13), we divided the patients into three subgroups: Subgroup I, hemorrhagic foci observed only on SWI and not on FLAIR; Subgroup II, hemorrhagic foci observed on both SWI and FLAIR in the same brain regions; and Subgroup III, any cases with additional foci on SWI in other brain regions. We investigated the clinical course and compared lesion numbers and distributions of hemorrhagic lesions on SWI among the subgroups.ResultsThree clinical variables (hospitalization period in intensive care unit, total days of hospitalization, and outcome based on Pediatric Cerebral Performance Category Scale score) showed significant relevance to the three subgroups. Subgroup I showed the fewest lesions followed by Subgroups II and III, respectively. In all three subgroups, lesions were most abundant in cortical regions. Lesion in the thalamus, basal ganglia, corpus callosum, and brainstem was least in Subgroup I and gradually increased in Subgroups II and III. Such distinction was more significant in the moderate-to-severe group when compared with the mild group.ConclusionsIn cases of pediatric traumatic brain injury, categorizing patients into one of the above three subgroups based on hemorrhagic lesions on SWI and FLAIR is a promising method for predicting patient’s clinical outcome.

Expression of matrix metalloproteinase-2 and -9 in human ligamentum flavum cells treated with tumor necrosis factor-α and interleukin-1β

OBJECTnAn in vitro study was performed to understand the potential roles of matrix metalloproteinase (MMP)-2 and MMP-9 in the elastin degradation of human ligamentum flavum (LF) cells via treatment with tumor necrosis factor-α (TNFα) and interleukin-1β (IL-1β). Previous studies have identified a decreased elastin to collagen ratio in hypertrophic LF. Among the extracellular matrix remodeling endopeptidases, MMP-2 and MMP-9 are known to have elastolytic activity. The hypothesis that activated LF cells exposed to inflammation would secrete MMP-2 and MMP-9, thereby resulting in elastin degradation, was examined.nnnMETHODSnTo examine MMP-2 and MMP-9 expression in human LF, cells were isolated and cultured from LF tissues that were obtained during lumbar disc surgery. Isolated LF cells were equally divided into 3 flasks and subcultured. Upon cellular confluency, the LF cells were treated with TNFα, IL-1β, or none (as a control) and incubated for 48 hours. The conditioned media were collected and assayed for MMP-2 and MMP-9 using gelatin zymography and Western blot analysis. The electrophoresis bands were compared on densitometric scans using ImageJ software.nnnRESULTSnThe conditioned media from the isolated human LF cells naturally expressed 72-kD and 92-kD gelatinolytic activities on gelatin zymography. The IL-1β-treated LF cells presented sustained increases in the proenzyme/zymogen forms of MMP-2 and -9 (proMMP-2 and proMMP-9), and activeMMP-9 expression (p = 0.001, 0.022, and 0.036, respectively); the TNFα-treated LF cells showed the most elevated proMMP9 secretion (p = 0.006), as determined by Western blot analyses. ActiveMMP-2 expression was not observed on zymography or the Western blot analysis.nnnCONCLUSIONSnTNFα and IL-1β promote proMMP-2 and proMMP-9 secretion. IL-1β appears to activate proMMP-9 in human LF cells. Based on these findings, selective MMP-9 blockers or antiinflammatory drugs could be potential treatment options for LF hypertrophy.

Predictors of Outcome in Patients with Cervical Spondylotic Myelopathy Undergoing Unilateral Open-Door Laminoplasty

Objective This study aimed to analyze prognostic factors affecting surgical outcomes of expansive laminoplasty for cervical spondylotic myelopathy (CSM). Methods Using the Frankel scale and Japanese Orthopaedic Association (JOA) scale, we retrospectively reviewed the outcomes of 45 consecutive patients who underwent modified unilateral open-door laminoplasty using hydroxyapatite spacers and malleable titanium miniplates between June 2008 and May 2014. The patients were assigned to the good and poor clinical outcome groups, with good outcome defined as a JOA recovery rate >75%. Results The mean preoperative JOA scale was significantly higher in the good outcome group (14.95±3.21 vs. 10.78±6.07, p<0.001), whereas the preoperative cervical range of motion (ROM) in this group was significantly lower (29.89°±10.11 vs. 44.35°± 8.88, p<0.001). In univariate analysis, a high preoperative JOA scale (odds ratio (OR) 1.271, 95% confidence interval (CI) 1.005-1.607) and low preoperative cervical ROM(OR 0.858, 95% CI 0.786-0.936) were statistically correlated with good outcomes. Furthermore, these factors demonstrated an independent association with clinical outcomes (preoperative JOA scale: OR 1.344, 95% CI 1.019-1.774, p=0.036; preoperative cervical ROM: OR 0.860, 95% CI 0.788-0.940, p=0.001). Conclusion In this study, a high preoperative JOA scale was associated with good clinical outcome after laminoplasty, whereas a higher preoperative cervical spine ROM was associated with poor clinical outcome. This may suggests that cervical mobility and preoperative neurological status affect clinical outcomes of laminoplasty.

Intracranial Undifferentiated Sarcoma Arising from a Low-Grade Glioma: A Case Report and Literature Review.

Undifferentiated sarcomas are rarely identified in the intracranial region. A 23-year-old man was admitted with a chief complaint of headache. Initial magnetic resonance images showed signs of low-grade glioma in the frontal lobe. Stereotactic biopsy was performed, and a diagnosis of diffuse astrocytoma was confirmed. Three months later, the patient presented with a high-grade tumor as seen on imaging studies. He underwent total resection of the tumor and histopathological tests identified an undifferentiated sarcoma. The patient died eight months later due to massive tumor bleeding. To the best of our knowledge, this is the first report of undifferentiated sarcoma arising from low-grade glioma without any chemotherapy or radiotherapy.

Single-Stage Transpedicular Vertebrectomy and Expandable Cage Placement for Treatment of Unstable Mid and Lower Lumbar Burst Fractures.

Study Design: Retrospective clinical and radiographic study. Objective: To examine the efficacy and safety of vertebrectomy and expandable cage placement by a single-stage posterior approach for unstable mid and lower lumbar burst fractures (below the L3). Summary of Background Data: Patients with unstable mid and lower lumbar burst fractures require surgical treatment to relieve pain, address paralysis, and stabilize the spine to prevent further segmental deformity. However, controversy remains regarding the optimal surgical treatment. Materials and Methods: Eleven patients underwent single-stage posterior-only vertebral column resection and vertebral body reconstruction using an expandable cage. Neurological status was classified using the American Spinal Injury Association (ASIA) Impairment Scale, whereas functional outcome was analyzed using a visual analog scale for back pain. Segmental Cobb angles were measured above and below the fractured vertebral body preoperatively, immediate postoperatively, and at the last follow-up. Results: The preoperative neurological status was ASIA grade E in 2 patients, grade D in 5 patients, grade C in 2 patients, and grade B in 2 patients. Postoperatively, neurological stability was demonstrated in 3 patients (27%), and 8 (73%) showed improvement in the ASIA grade. The mean preoperative visual analog scale score was 8.3, which decreased to 4.5 postoperatively, and to 1.8 at the final follow-up. The mean preoperative segmental lordotic angle was 9.2 degrees, which increased to 16.9 degrees postoperatively, and decreased to 15.1 degrees at the last follow-up. The mean operating time was 208.8 minutes, and the mean blood loss was 1006.3 mL. Regarding surgical complications, 1 patient experienced a dural tear and 1 patient demonstrated cage subsidence. Conclusions: The results of this small series suggest the feasibility, efficacy, and safety of this surgical option for unstable mid and lower lumbar burst fractures. This technique from a single posterior approach offers several advantages over traditional anterior or combined approaches using strut graft or nonexpandable implants.

Tophaceous Gout in the Lumbar Spinal Canal Mimicking Epidural Spinal Tumor

Gout is an inflammatory arthritis characterized by deposition of monosodium urate crystals in joints. Though gout frequently involves the big toe or other extremities, it rarely occurs in the spinal canal. A 35-year-old man presented with left L5 radiculopathy. He had leg pain for 8 months and received several epidural steroid injections. Magnetic resonance imaging revealed a 1.7×1.1-cm ovoid contrast-enhancing mass, causing pressure erosion of the left L5 pedicle. Microscopic laminotomy was performed at the left L5 lamina. White chalky materials, identified at the left lateral recess of the spinal canal, were removed in a piecemeal manner. The histopathologic diagnosis was tophaceous gout. Although the patient’s radiating pain did not resolve postoperatively, it was dramatically relieved with uric acid-lowering medications. If a mass effect is suspected, surgical removal of gouty tophi might aid in symptom release and definite diagnosis. Medical treatment after rheumatology consultation is crucial.