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Youn-Kwan Park, Joo-Han Kim and Heung-Seob Chung

Object

The authors describe a microsurgical technique for the preservation of the ligamentum flavum and the long-term surgery-related results, including an independent assessment of outcome.

Methods

Three hundred seventy-seven patients underwent ligament-sparing microsurgical discectomy for a previously untreated single-level lumbar disc herniation and were followed for more than 2 years. A successful outcome at 6 months was demonstrated in 93.9% of the patients. At a median follow-up period of 30 months, successful patient-assessed outcome was 84.1%. During the mean follow-up period of 4.2 years (range 2–6.5 years), recurrent disc herniation was detected in 18 patients (4.8%). These patients all underwent repeated surgery. The overall surgery-related rate of complications was 1.3%.

Conclusions

The authors conclude that ligament-sparing microdiscectomy is a safe procedure, with a favorable success rate and minimal morbidity. Reoperation is safer and easier when using this technique compared with traditional ones.

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Youn-Kwan Park, Joo Han Kim, Hung Seob Chung and Jung Keun Suh

Object. When performing surgery, the extraforaminal window is very narrow at the L5—S1 level. The authors describe a microsurgical method for decompression of the L-5 nerve root trapped between a marginal osteophyte of the vertebral body and the transverse process. The procedure was performed in 16 patients with extraforaminal stenosis.

Methods. The cranial part of the L5—S1 facet joint and the caudal portion of the pedicle and transverse process of L-5 were removed via a midline skin incision and partial resection of the pars interarticularis; a high-speed drill was used as was a surgical microscope. The affected nerve root was decompressed and mobilized cranially.

Postoperatively all patients reported excellent relief of their sciatic pain, and there were no technique-associated complications. There was no recurrence during the follow-up period, that ranged from 14 to 70 months.

Conclusions. The authors recommend this technique for the effective decompression of symptomatic extraforaminal L5—S1 stenosis. The need for a dangerous and tedious removal of the vertebral osteophyte together with spinal fusion is avoided.

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Jung Jae Park, Hong Joo Moon, Jin Hyun Park, Taek Hyun Kwon, Youn-Kwan Park and Joo Han Kim

OBJECT

To determine the role played by mitogen-activated protein kinase (MAPK) signaling in the interactions between macrophages and intervertebral disc (IVD) cells, it was hypothesized that MAPK inhibition would modulate the production of the proinflammatory cytokines associated with inflammatory reaction in IVD cells.

METHODS

Human annulus fibrosus (AF) and nucleus pulposus (NP) cells were cocultured with phorbol myristate acetate-stimulated macrophage-like THP-1 cells, with and without SB202190 (a p38-α and -β inhibitor), SP600125 (a c-Jun N-terminal kinase [JNK] inhibitor), and PD98059 (an extracellular signal-regulated kinase [ERK] 1/2 inhibitor). The cytokines in conditioned media from cocultured and macrophage-exposed (nemotic) cells were assayed using enzyme-linked immunosorbent assays (ELISAs).

RESULTS

Interleukin (IL)-6 and IL-8 were secreted in greater quantities by the cocultured cells compared with naive IVD cells and macrophages (MΦ) cultured alone. The tumor necrosis factor (TNF)- α and IL-6 levels produced by the NP cells cocultured with MΦs (NP-MΦ) were significantly lower than those produced by AF cells cocultured with MΦs (AF-MΦ). SB202190 dose-dependently suppressed IL-6 secretion by AF-MΦ and NP-MΦ cocultures, and 10 μM SB202190 significantly decreased IL-6 and IL-8 production in nemotic AF and NP pellets. SP600125 at 10 μM significantly suppressed the production of TNF α IL-6. and IL-8 in AF-MΦ and NP-MΦ cocultures and significantly suppressed IL-1β production in the NP-MΦ coculture. Administration of 10 μM PD98059 significantly decreased IL-6 levels in the AF-MΦ coculture, and decreased the levels of TNF α and IL-8 in both the AF-MΦ and NP-MΦ cocultures.

CONCLUSIONS

The present study shows that inhibitors of p38 MAPK effectively controlled IL-6 production during inflammatory reactions and that JNK and ERK1/2 inhibitors successfully suppressed the production of major proinflammatory cytokines during interactions between macrophages and IVD cells. Therefore, selective blockade of these signals may serve as a therapeutic approach to symptomatic IVD degeneration.

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Dong-Hyuk Park, Youn-Kwan Park, Jae-In Oh, Taek-Hyun Kwon and Hung-Seob Chung

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Taek-Hyun Kwon, Youn-Kwan Park, Dong-Jun Lim, Tai-Hyoung Cho, Yong-Gu Chung, Hung-Seob Chung and Jung-Keun Suh

Object. A wide variation in postoperative drainage volumes is observed during treatment of chronic subdural hematoma (CSDH) with twist-drill or burr-hole craniostomy and closed-system drainage. In this study the authors investigate the causes of the variation, the clinical significance thereof, and its influence on treatment outcome.

Methods. A total of 175 cases were investigated between January 1991 and December 1997. Of these, 145 patients had surgery for CSDH, of whom 30 had bilateral lesions. The cases of CSDH were divided into five subtypes (low-density, isodense, high-density, mixed-density, and layering types) on the basis of the brain computerized tomography (CT) findings. Burr-hole craniostomies with closed-system drainage were performed in all patients and the drainage was maintained for 5 days, during which daily amounts of fluid were measured. The mean drainage volume over 5 days was 320 ml, with the largest volume (413 ml) seen in the low-density type and the smallest (151 ml) in the mixed-density type of CSDH. There were recurrences in six patients (seven instances, 4%). The mixed-density type had the highest recurrence rate (8.6%), whereas there was no recurrence for the low-density type. There were no recurrences in 81 patients in whom the total drainage volumes for 5 days were more than 200 ml, but there were recurrences in six (seven instances) of 94 patients in whom the total drainage volume was less than 200 ml.

Conclusions. The postoperative drainage volumes varied greatly because of differences in the outer membrane permeability of CSDH, and such variation seems to be related to the findings on the CT scans obtained preoperatively. Patients with CSDH in whom there is less postoperative drainage than expected should be carefully observed, with special attention paid to the possibility of recurrence.

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Bum-Joon Kim, Junseok W. Hur, Jong Soo Park, Joo Han Kim, Taek-Hyun Kwon, Youn-Kwan Park and Hong Joo Moon

OBJECT

An 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.

METHODS

To 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.

RESULTS

The 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.

CONCLUSIONS

TNFα 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.

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Suk-Joo Hong, Youn-Kwan Park, Jung Hyuk Kim, Soon Hyuck Lee, Kyung Nam Ryu, Cheol Min Park and Yeon Soo Kim

Object

The authors evaluate the biomechanical properties of vertebral bodies (VBs) stabilized with calcium phosphate (CaP) cements for use in vertebroplasty in comparison with polymethylmethacrylate (PMMA).

Methods

In the first phase of the study, 73 VBs (T3–L2; thoracic region [T3–8] and thoracolumbar region [T9–L2]) were collected from seven fresh human cadavers. Compression tests were performed before and after vertebroplasty using PMMA (compression strength 80 MPa) and three kinds of CaP cements—CaP1 (5 MPa), CaP2 (20 MPa), and CaP3 (50 MPa). The authors compared the maximal compression loads (MCLs) and stiffness before and after vertebroplasty in each of the four cement groups. In the second phase of the study, 18 paired spinal units (PSUs) were collected from three fresh human cadavers, and the authors injected two types of cement selected from the first phase of the study into the lower level of six PSUs. They compared the MCLs of the untreated and two treated groups (there were six PSUs in each type of group) to analyze the tendency of inducing compression fractures in the upper level of the PSUs.

The MCLs of the PMMA-injected vertebrae were significantly increased after vertebroplasty. The MCL levels of the CaP3-injected vertebrae and the CaP2-injected thoracolumbar vertebrae were decreased from those of untreated vertebrae without being significant. The MCLs of CaP1-injected vertebrae and CaP2-injected thoracic vertebrae were significantly decreased after vertebroplasty. The stiffness of all cement groups was decreased after vertebroplasty compared with initial stiffness, significantly so in all three thoracic CaP groups. In the second compression test with PSUs, the MCLs of the CaP2- and CaP3-injected PSUs were not significantly different from those of the untreated control PSUs.

Conclusions

The CaP3-injected vertebrae restored the MCLs of human vertebrae closer to their initial levels than the PMMA-injected vertebrae did. The CaP2- and CaP3-injected PSUs showed no tendency to induce compression fractures in adjacent VBs.

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Hong Joo Moon, Bong-Kyung Shin, Joo Han Kim, Jong-Hyun Kim, Taek-Hyun Kwon, Hung-Seob Chung and Youn-Kwan Park

Intramedullary teratomas, particularly adult cervicothoracic lesions, are extremely rare. Up to now only 6 cases of intramedullary cervical teratomas have been reported in adults, and all of these were histologically mature. The authors present the case of a 35-year-old man with progressive myelopathic symptoms who was admitted through an outpatient clinic and was surgically treated. The characteristics, diagnosis, epidemiology, and treatment of cervical intramedullary teratomas in adults are also reviewed. Postoperative MR imaging showed that the tumor had been near totally removed, and severely adherent tissue remained ventrocranially with tiny focal enhancement on follow-up MR imaging. Pathological examinations revealed immature teratoma without any malignant component. Adjuvant therapy was not performed. Although no change in neurological findings and symptoms was apparent postoperatively, lesion regrowth was demonstrated on MR imaging 4 months after surgery. At 8 months postoperatively, myelopathic symptoms had developed and a huge intramedullary tumor recurred according to MR imaging. This case is the seventh reported instance of intramedullary cervical teratoma in an adult, and the first case report of the immature type with malignant features.