Seung-Jae Hyun

DIFFERENCES IN NATURE OF DEFECTS BETWEEN SRBI2TA2O9 AND BI4TI3O12

X-ray photoemission spectroscopy measurements were executed to compare the nature of defects in SrBi2Ta2O9 (SBT) and Bi4Ti3O12 (BTO) films. In the SBT film, it was found that the oxygen ions at the metal–oxygen octahedra were much more stable than those at the Bi2O2 layers. On the other hand, for the BTO film, oxygen vacancies could be induced both at the titanium–oxygen octahedra and at the Bi2O2 layers. We suggested that the difference in stability of the metal–oxygen octahedra should be related to different fatigue behaviors of the SBT and the BTO films.

Clinical Outcomes and Complications after Pedicle Subtraction Osteotomy for Fixed Sagittal Imbalance Patients : A Long-Term Follow-Up Data

OBJECTIVE Clinical, radiographic, and outcomes assessments, focusing on complications, were performed in patients who underwent pedicle subtraction osteotomy (PSO) to assess correction effectiveness, fusion stability, procedural safety, neurological outcomes, complication rates, and overall patient outcomes. METHODS We analyzed data obtained from 13 consecutive PSO-treated patients presenting with fixed sagittal imbalances from 1999 to 2006. A single spine surgeon performed all operations. The median follow-up period was 73 months (range 41-114 months). Events during perioperative course and complications were closely monitored and carefully reviewed. Radiographs were obtained and measurements were done before surgery, immediately after surgery, and at the most recent follow-up examinations. Clinical outcomes were assessed using the Oswestry Disability Index and subjective satisfaction evaluation. RESULTS Following surgery, lumbar lordosis increased from -14.1 degrees +/- 20.5 degrees to -46.3 degrees +/- 12.8 degrees (p < 0.0001), and the C7 plumb line improved from 115 +/- 43 mm to 32 +/- 38 mm (p < 0.0001). There were 16 surgery-related complications in 8 patients; 3 intraoperative, 3 perioperative, and 10 late-onset postoperative. The prevalence of proximal junctional kyphosis (PJK) was 23% (3 of 13 patients). However, clinical outcomes were not adversely affected by PJK. Intraoperative blood loss averaged 2,984 mL. The C7 plumb line values and postoperative complications were closely correlated with clinical results. CONCLUSION Intraoperative or postoperative complications are relatively common following PSO. Most late-onset complications in PSO patients were related to PJK and instrumentation failure. Correcting the C7 plumb line value with minimal operative complications seemed to lead to better clinical results.

Comparison of standard 2-rod constructs to multiple-rod constructs for fixation across 3-column spinal osteotomies.

Study Design. Retrospective matched-cohort comparative study. Objective. Compare radiographical outcomes after the use of a standard 2-rod construct (2-RC) versus a multiple-rod construct (multi-RC) across 3-column osteotomy sites in a matched cohort with severe kyphosis and/or scoliosis with minimum 2-year follow-up. Summary of Background Data. Three-column osteotomies are used for treating severe spinal deformities, typically with a standard 2-RC across the highly unstable osteotomy site. Methods. Between 1996 and 2010, patients undergoing a 3-column osteotomy by a single surgeon were matched for age/diagnosis/vertebra(e) resected/levels fused and curve magnitude. Sixty-six control patients with a 2-RC were identified and appropriately matched to 66 consecutive patients with a multi-RC across the 3-column osteotomy site. Each group included 50 patients with lumbar pedicle subtraction osteotomy and 16 patients with vertebral column resection. Radiographs were measured using standard adult deformity criteria. Results. Averages were compared for 2-RC versus multi-RC demonstrating no statistical differences in mean age at surgery, vertebrae resected, levels fused, bone morphogenetic protein used (patients), or average preoperative Cobb magnitude. There were significant differences in the occurrence of rod breakage and revision surgery for pseudarthroses at the 3-column osteotomy site (rod breakage: 2-RC: 11 vs. multi-RC: 2, P = 0.002; and revision: 2-RC: 6 vs. multi-RC: 0, P = 0.011). There was no complete implant failure in the multi-RC group but 2 patients had partial implant failure without symptomatic pseudarthrosis. Eight patients in each group (12%) developed a pseudarthrosis above or below the osteotomy site. Conclusion. The use of a multi-RC is a safe, simple, and effective method to provide increased stability across 3-column osteotomy sites to significantly prevent implant failure and symptomatic pseudarthrosis versus a standard 2-RC. We strongly recommend using a multi-RC to stabilize 3-column osteotomies of the thoracic and lumbar spine. Level of Evidence: 3

The Time Course of Range of Motion Loss After Cervical Laminoplasty: A Prospective Study With Minimum Two-Year Follow-up

Study Design. A prospective study. Objective. To identify the time-dependent change in range of motion (ROM) after cervical laminoplasty. Summary of Background Data. Although numerous studies have reported on the loss of flexion/extension ROM associated with laminoplasty, few have reported on the time course of this loss of motion. Methods. Twenty-three patients who received unilateral open-door laminoplasties, including miniplate fixation over 2 levels, were serially evaluated at regular set intervals after surgery. The mean follow-up period was 26.78 months (range: 24–41 months). Twelve patients had OPLL and 11 patients had cervical spondylotic myelopathy. Enrolled patients were divided into 2 groups (ossification of posterior longitudinal ligament [OPLL] and cervical spondylotic myelopathy) to compare the ROM between the OPLL and the spondylosis patients. We evaluated the time-dependent neck ROM changes by taking neutral, flexion, and extension radiographs before surgery and at 1, 3, 6, 9, 12, 18, and 24 months after surgery. Postoperative neck and arm pain was evaluated using a numerical rating scale. Results. The preoperative, and 1-, 3-, 6-, 9-, 12-, 18-, and 24-month postoperative ROM figures were 37.8° ± 14.6°, 34.1° ± 12.9°, 35.0° ± 12.3°, 30.3° ± 13.0°, 28.6° ± 15.1°, 27.3° ± 12.4°, 26.1° ± 14.8°, and 25.9° ± 13.2°, respectively, and at the most recent follow-up, ROM was 25.8 ± 15.2°. Thus, the mean ROM decreased by 10.1° ± 9.5° (31.66%) after surgery (P = 0.002). In OPLL group, we observed a more limited cervical ROM than in cervical spondylotic myelopathy group (35.3% vs. 29.2%). However, the rate of ROM reduction slowed with time in both groups (P = 0.000). Postoperative axial pain did not correlate with the degree of serial cervical ROM. Conclusion. The results suggest that the loss of cervical ROM is time-dependent and plateaus by18 months after surgery, with no further decreases thereafter.

Long-term outcomes of surgical resection with or without adjuvant radiation therapy for treatment of spinal ependymoma: a retrospective multicenter study by the Korea Spinal Oncology Research Group

BACKGROUND We sought to determine the surgical treatment and functional outcome and identify the predictors of survival in a retrospective cohort of patients with spinal cord ependymoma using data collected from the Korea Spinal Oncology Research Group database. METHODS The data regarding 88 patients who had been surgically treated for histologically confirmed spinal cord intramedullary and extramedullary ependymoma from January 1989 to December 2009 were retrospectively reviewed. RESULTS Histopathological examination revealed myxopapillary ependymoma in 24 patients, ependymoma in 61 patients, and anaplastic ependymoma in 3 patients. Gross total removal was achieved in 72 patients, subtotal removal in 15 patients, and partial removal in 1 patient. Twenty patients were treated with postoperative radiation. Fifty-two patients had stable or improved postoperative neurological function, while 36 experienced neurological deterioration. A permanent decrease in McCormick classification grade was seen in 17 patients. The progression-free survival rate was 87% for all patients at 5 years and 80% at 10 years. During follow-up, local recurrence/progression was seen in 13 patients. Diffuse meningeal spread developed in 2 anaplastic ependymoma patients. Postoperative radiotherapy after incomplete resection did not significantly correlate with longer times to recurrence. Multivariate analysis revealed histology and surgical extent of resection as independent predictors of longer progression-free survival. CONCLUSIONS Gross total removal alone is a good treatment strategy for spinal ependymomas. Early diagnosis and surgery, before severe paralysis, are important to obtain good functional outcomes. Subtotal resection with radiation therapy for intramedullary lesions appears to offer no advantages over gross total removal.

Comparative analysis of 3 different construct systems for single-level anterior cervical discectomy and fusion: stand-alone cage, iliac graft plus plate augmentation, and cage plus plating.

Study Design: A retrospective cohort-nested longitudinal study. Objective: To evaluate radiologic and clinically functional outcomes after single-level anterior cervical discectomy and fusion (ACDF) using 3 different fusion construct systems applying an accurate and reliable methodology. Summary of Background Data: ACDF is an established procedure that uses 3 different fusion construct systems: cage alone (CA), iliac tricortical bone block with plate (IP), and cage with plate construct (CP). The outcome of a previous study is quite different and did not correlate with experimental studies. Methods: ACDF was performed on 158 patients (90 male and 68 female), who were followed up for >12 months. The patients were divided into the following 3 treatment groups: CA, IP, and CP. Factors related to outcome were also evaluated. Fusion rate, subsidence rate, and cervical angles were used to measure radiologic outcome. The Odom criteria and the visual analog scale were used to evaluate the clinical outcome. Results: The fusion rate was higher for patients in the IP (87.1%) and CP (79.5%) groups than for those in the CA group (63.2%) after 12 months of follow-up (P=0.019). The subsidence rate was lower for patients in the IP (28.1%) and CP (38.5%) groups than for those in the CA group (58.6%) (P=0.010). Subsidence occurred for the anterior height regardless of constructs. Radiating arm pain showed greater relief in the CP group than in the CA group (P=0.015). It improved more in the CP group than in the IP group, but the differences were not statistically significant (P=0.388). Other clinical outcomes did not show significant differences. Conclusions: The trend of excellent radiologic outcome was observed for IP≥CP>CA. Plating may play a key role in the support of anterior height. As a result, plating prevents segmental kyphosis and subsidence and promotes bone fusion. Although the overall clinical outcomes were not different among the 3 groups, except for arm pain, more favorable trends regarding clinical outcome were observed for CP≥IP>CA.

Laminoplasty versus laminectomy and fusion for multilevel cervical myelopathy: a meta-analysis of clinical and radiological outcomes

OBJECT Posterior cervical surgery, expansive laminoplasty (EL) or laminectomy followed by fusion (LF), is usually performed in patients with multilevel (≥ 3) cervical spondylotic myelopathy (CSM). However, the superiority of either of these techniques is still open to debate. The aim of this study was to compare clinical outcomes and postoperative kyphosis in patients undergoing EL versus LF by performing a meta-analysis. METHODS Included in the meta-analysis were all studies of EL versus LF in adults with multilevel CSM in MEDLINE (PubMed), EMBASE, and the Cochrane library. A random-effects model was applied to pool data using the mean difference (MD) for continuous outcomes, such as the Japanese Orthopaedic Association (JOA) grade, the cervical curvature index (CCI), and the visual analog scale (VAS) score for neck pain. RESULTS Seven studies comprising 302 and 290 patients treated with EL and LF, respectively, were included in the final analyses. Both treatment groups showed slight cervical lordosis and moderate neck pain in the baseline state. Both groups were similarly improved in JOA grade (MD 0.09, 95% CI -0.37 to 0.54, p = 0.07) and neck pain VAS score (MD -0.33, 95% CI -1.50 to 0.84, p = 0.58). Both groups evenly lost cervical lordosis. In the LF group lordosis seemed to be preserved in long-term follow-up studies, although the difference between the 2 treatment groups was not statistically significant. CONCLUSIONS Both EL and LF lead to clinical improvement and loss of lordosis evenly. There is no evidence to support EL over LF in the treatment of multilevel CSM. Any superiority between EL and LF remains in question, although the LF group shows favorable long-term results.

Prognostic factors associated with perioperative ischemic complications in adult-onset moyamoya disease

BackgroundTo clarify the risk factors associated with perioperative ischemic complications in adult-onset moyamoya disease.Material and methodsThe incidence and causes of perioperative ischemic complications in adult-onset moyamoya disease were retrospectively examined by reviewing 165 surgically treated adult patients. Two hundred forty-six revascularization procedures were performed in these patients.ResultsThere were 19 (7.7%) perioperative ischemic complications (four infarctions with neurological sequelae and 15 reversible ischemic neurological deficits with a new lesion). The complications occurred in the initially affected hemispheres in 17 (89.4%) of the 19 ischemic complications, regardless of the side of the operation. Multiple ischemic episodes (defined as over four-symptom episodes before treatment), the presence of a preoperative low density area (LDA) on computed tomographic (CT) scanning, and a high signal intensity on diffusion-weighted magnetic resonance (MR) imaging were significantly correlated with perioperative ischemic complications (p < 0.05, p < 0.05, and p < 0.01, respectively). Non-surgical hemodynamic risk factors, i.e., hypercapnia, hypocapnia, or hypotension/hypovolemia, were noted in all of the 19 cases. None of the surgical factors evaluated were associated with the complications identified.ConclusionsAvoidance of non-surgical hemodynamic risk factors as well as maintaining vital collateral vessels is essential for the prevention of perioperative hemodynamic brain damage in patients with adult-onset moyamoya disease. In addition, very close monitoring of the perioperative care of patients with preoperative multiple ischemic episodes and an LDA or high signal intensity on preoperative CT or diffusion-weighted MR imaging is extremely important.

Direct decompressive surgery followed by radiotherapy versus radiotherapy alone for metastatic epidural spinal cord compression: a meta-analysis.

Study Design. A systemic review and meta-analysis. Objective. To compare the ambulatory status and survival for metastatic epidural spinal cord compression (MESCC) in patients treated with direct decompressive surgical resection (DDSR) followed by radiotherapy (RTx) with those in patients treated with RTx alone. Summary of Background Data. Surgical techniques have remarkably evolved from decompressive laminectomy without ventral tumor excision to DDSR, which has displayed favorable outcomes since the 2000s. RTx alone has also evolved and is regarded to have accomplished outcome comparable with that of the surgery. The optimal treatment of MESCC has not been clearly defined yet. Methods. We searched MEDLINE, EMBASE, and the Cochrane library in July 2013. Comparative studies enrolled patients with similar performance, primary cancer, age, and sex at the baseline state were included. Outcome measures included ambulatory status and overall survival rate. We did a fixed-effects meta-analysis of the ambulatory status and survival in patients with MESCC compared with DDSR+RTx and RTx alone. Results. Five studies were used to obtain data from 238 and 1137 patients treated with DDSR+RTx and RTx alone, respectively. The DDSR+RTx group displayed substantial improvement in ambulatory status after the treatment that was superior to the improvement in the RTx-alone group (relative risk [RR], 1.43; 95% confidence interval [CI], 1.14–1.78) in a fixed-effects model and significantly lower deterioration after treatment than the RTx group (RR, 0.35; 95% CI, 0.19–0.63). The DDSR+RTx group showed significant improvement in the survival rate at 6 months post-treatment (RR, 1.21; 95% CI, 1.09–1.33). Similar findings were observed at 12 months post-treatment (RR, 1.32; 95% CI, 1.12–1.56). Conclusion. The meta-analysis indicates that DDSR+RTx may produce better clinical improvement of ambulation status and survival than RTx alone in the treatment of MESCC. Additional prospective studies are warranted to better address this question. Level of Evidence: 1

Range of motion loss after cervical laminoplasty: a prospective study with minimum 5-year follow-up data.

BACKGROUND CONTEXT Although numerous studies have reported on the loss of flexion-extension range of motion (ROM) associated with laminoplasty, few have reported on the time course of this loss of motion for a long-term follow-up period. PURPOSE We previously reported our early data on postlaminoplasty cervical ROM. In this article, we describe our minimum 5-year follow-up data to identify the time-dependent change in ROM after cervical laminoplasty. STUDY DESIGN A prospective cohort study. PATIENT SAMPLE The procedure was performed in 23 patients. Eighteen patients with a minimum 5-year follow-up were included in the study. OUTCOME MEASURES The time-dependent neck ROM changes observed in the neutral, flexion, and extension radiographs were used to measure the radiological outcome. The Japanese Orthopaedic Association classification and a numerical rating scale of axial neck pain and arm pain were used to evaluate clinical outcome. METHODS Twenty-three patients who received unilateral open-door laminoplasties, including miniplate fixation over three levels, were serially evaluated at regular set intervals postoperatively. Eighteen patients with a minimum 5-year follow-up were included in the study. The mean follow-up period was 68.1 months (range, 60-78 months). Nine patients had ossification of posterior longitudinal ligament (OPLL) and nine patients had cervical spondylotic myelopathy (CSM). Enrolled patients were divided into subgroups (OPLL vs. CSM; autofusion vs. nonautofusion) to compare the ROM between the groups. We evaluated the time-dependent neck ROM changes by taking neutral, flexion, and extension radiographs preoperatively and at 1, 3, 6, 9, 12, 18, and 24 months postoperatively. Follow-up radiographs were taken annually after a 2-year follow-up. RESULTS The preoperative and 1-, 3-, 6-, 12-, 24-, 36-, 48-, and 60-month postoperative ROM figures were 39.9 ± 11.2°, 35.0 ± 9.2°, 33.0 ± 11.0°, 30.1 ± 10.4°, 25.8 ± 13.1°, 24.7 ± 10.0°, 23.8 ± 6.5°, 24.6 ± 8.3°, and 23.6 ± 9.4°, respectively, and at the most recent follow-up, ROM was 24.5 ± 10.1°. Thus, the mean ROM decreased by 15.4 ± 8.4° (38.5%) by the last follow-up (p<.0001). In the OPLL group, we observed a more limited cervical ROM than in the CSM group (47.2% vs. 72.7%). As expected, in the laminar autofusion group, the ROM decreased significantly (55.6% decrease), whereas in the nonautofusion group, the ROM decreased less significantly (13.4% decrease) at the last follow-up. Postoperative axial pain did not correlate with the cervical ROM. CONCLUSIONS These results suggest that the loss of cervical ROM after laminoplasty is time-dependent, and patients with OPLL and laminar autofusion had less ROM. Postlaminoplasty ROM reduction can recover after several years, unless laminar autofusion occurs.