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Dong-Yun Kim

Publications and source records attributed to Dong-Yun Kim.

9 recordsLinked to original sources
PubMed2006

On the generalized poisson regression mixture model for mapping quantitative trait loci with count data.

Statistical methods for mapping quantitative trait loci (QTL) have been extensively studied. While most existing methods assume normal distribution of the phenotype, the normality assumption could be easily violated when phenotypes are measured in counts. One natural choice to deal with count traits is to apply the classical Poisson regression model. However, conditional on covariates, the Poisson assumption of mean-variance equality may not be valid when data are potentially under- or overdispersed. In this article, we propose an interval-mapping approach for phenotypes measured in counts. We model the effects of QTL through a generalized Poisson regression model and develop efficient likelihood-based inference procedures. This approach, implemented with the EM algorithm, allows for a genomewide scan for the existence of QTL throughout the entire genome. The performance of the proposed method is evaluated through extensive simulation studies along with comparisons with existing approaches such as the Poisson regression and the generalized estimating equation approach. An application to a rice tiller number data set is given. Our approach provides a standard procedure for mapping QTL involved in the genetic control of complex traits measured in counts.

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PubMed2006

An oblique paraspinal approach for intracanalicular disc herniations of the upper lumbar spine: technical case report.

OBJECTIVE: To present our experience of treating the central or paramedian disc herniations of the upper lumbar levels through a paraspinal approach. CLINICAL PRESENTATION: We present four patients with intracanalicular disc herniations at the L1-L2 or L2-L3 level. All patients had unilateral or bilateral radicular leg pain and motor weakness. TECHNIQUE: Considering the unique characteristics of the upper lumbar spine, we performed the oblique paraspinal approach to expose the central portion of disc and removed the herniated disc effectively. Postoperatively, their symptoms were improved. There was no instability during the follow-up period. CONCLUSION: The oblique paraspinal approach for the treatment of central disc herniations at the upper lumbar levels is an effective nonfusion technique that preserves most of the facet joint and provides a wide surgical field.

Adult↗
PubMed2005

Validation of the Korean version of the oswestry disability index.

STUDY DESIGN: Validation of a translated, culturally adapted questionnaire. OBJECTIVES: To translate and culturally adapt a Korean version of the Oswestry Disability Index (ODI) and to validate its use in Korean patients. SUMMARY OF BACKGROUND DATA: The ODI is one of the most widely used and validated instruments for measuring disability in spinal disorders. However, no validated Korean version of the index was available at the time our study was initiated. METHODS: The study was carried out in three phases: the first was translation into Korean and cultural adaptation of the questionnaire; the second was a pilot study to assess the comprehensibility of the prefinal version and modification; the third was a reliability and validity study of the final version. The Korean version was tested on 206 patients with lumbar spinal disorders who had undergone operations at the authors' institute. Test-retest reliability, internal consistency, concurrent validity, and construct validity were investigated. Follow-up questionnaires were obtained from 39 patients at the 3-month postoperative follow-up meeting. Differences in the ODI, visual analog scale (VAS), and World Health Organization (WHO) quality of life assessment (WHOQOL-BREF) between preoperative and follow-up questionnaires were evaluated. The correlation of the postoperative ODI with the pain rating on a visual analog scale and WHOQOL-BREF was also analyzed. RESULTS: Test-retest reliability was assessed with 88 patients in a time interval of 48 hours. The intraclass correlation coefficient of test-retest reliability was 0.9167. Reliability estimated by the internal consistency reached a Cronbach's alpha of 0.84. The correlation of the preoperative ODI with the pain rating on a visual analog scale (100 mm) was r = 0.425 (P = 0.0001). The correlation between three of the WHOQOL-BREF domains (physical health, psychological health, and environment) and the ODI was statistically significant. The correlation coefficient between the ODI and physical health domain of the WHOQOL-BREF was r = -0.48 (P < 0.05). The correlations with psychological health and environment domains were low with r = -0.192 and -0.160, respectively, even though statistically significant (P < 0.05). The correlation of the postoperative ODI with the pain rating on a visual analog scale (100 mm) was r = 0.626 (P = 0.0001). The correlation between all four domains of the WHOQOL-BREF and the postoperative ODI was statistically significant. CONCLUSIONS: The results of this study indicate that the Korean version of the ODI is a reliable and valid instrument for the measurement of disability in Korean patients with lower back problems. The authors recommend this Korean version of the ODI for use in future clinical studies in Korea.

Adult↗
PubMed2005

Comparison of multifidus muscle atrophy and trunk extension muscle strength: percutaneous versus open pedicle screw fixation.

STUDY DESIGN: This study was conducted by retrospective case selection and prospective observation of longitudinal changes of the multifidus muscle cross-sectional area and of trunk extension muscle strength in percutaneous and open pedicle screw fixations. OBJECTIVES: To compare postoperative multifidus muscle atrophy and trunk muscle performance of percutaneous pedicle screw fixation against those of open pedicle screw fixation. SUMMARY OF BACKGROUND DATA: Recent attempts to combine percutaneous pedicle screw fixation with minimally invasive fusion techniques are based on an anecdotal presupposition that percutaneous pedicle screw fixation is superior to its open counterpart. However, the benefits of percutaneous pedicle screw fixation are currently poorly defined. METHODS: Nineteen enrolled patients were divided as follows: 11 in the open pedicle screw fixation group (OPF group) and eight in the percutaneous pedicle screw fixation group (PPF group). The preoperative and postoperative cross-sectional area and T2-weighted signal intensity of multifidus muscle were measured by MRI, and trunk extension muscle strength was measured. In addition, various clinical variables were compared between two groups. RESULTS: There was significant decrease in the cross-sectional area of multifidus muscle in the OPF group. In contrast, the results in the PPF group showed no statistical difference between preoperative results and that of the follow-up MRI. Although percutaneous pedicle screw fixation had positive effects on postoperative trunk muscle performance, clinical outcomes were not significantly different in areas of pain score, JOA score, and patient's opinion regarding the outcome of the surgery. However, percutaneous pedicle screw fixation caused less blood loss, and the proportion of patients who did not need postoperative oral analgesics was greater in the PPF group. CONCLUSIONS: Percutaneous pedicle screw fixation caused less paraspinal muscle damage than open pediclescrew fixation and had positive effects on postoperative trunk muscle performance.

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PubMed2004

Intravertebral vacuum phenomenon in osteoporotic compression fracture: report of 67 cases with quantitative evaluation of intravertebral instability.

OBJECT: The objectives of this study were to: 1) describe the incidence and clinical features of intravertebral vacuum phenomenon (IVVP) in a relatively large number of cases; 2) quantitatively evaluate intravertebral instability and determine the factors affecting instability; and 3) evaluate the efficacy of percutaneous vertebroplasty in the treatment of this phenomenon. METHODS: A retrospective review was conducted of the records of 67 patients with IVVP among 652 consecutive cases of osteoporotic compression fracture. Comparisons between the IVVP group and a control group, a stable group, and an unstable group were conducted. Percutaneous vertebroplasty was performed in all patients. There were 67 patients (10.3%) in whom there were 70 vacuum phenomena of the intravertebral space. Intravertebral vacuum phenomena occurred predominantly in the thoracolumbar junction (81%) and in patients with a longer duration of symptoms (10.6 +/- 9.8 months) compared with the control group. Of 59 vertebrae for which flexion-extension radiographs were available, 26 vertebrae were categorized as stable and 33 as unstable. Twenty-one vertebrae (64%) had undergone compression fracture in the unstable group compared with nine (35%) compression fractures in the stable group. There were 28 (85%) fractures of the wedged vertebrae in the unstable group compared with 16 (61%) fractures in wedged vertebrae in the stable group. Percutaneous vertebroplasty was performed with successful clinical outcome. CONCLUSIONS: Intravertebral vacuum phenomenon is more common than has been previously appreciated. The results of this study indicate that biomechanics, not ischemic or avascular theory, may play an important role in pathogenesis of this phenomenon. Percutaneous vertebroplasty was found to be a minimally invasive and effective procedure for the treatment of IVVP.

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PubMed2003

Comparative study of laparoscopic L5-S1 fusion versus open mini-ALIF, with a minimum 2-year follow-up.

Anterior lumbar interbody fusion (ALIF) is a widely accepted tool for management of painful degenerative disc disease. Recently, the modern laparoscopic surgical technique has been combined with ALIF procedure, with good early postoperative results being reported. However, the benefit of laparoscopic fusion is poorly defined compared with its open counterpart. This study aimed to compare perioperative parameters and minimum 2-year follow-up outcome for laparoscopic and open anterior surgical approach for L5-S1 fusion. The data of 54 consecutive patients who underwent anterior lumbar interbody fusion (ALIF) of L5-S1 from 1997 to 1999 were collected prospectively. More than 2-years' follow-up data were available for 47 of these patients. In all cases, carbon cage and autologous bone graft were used for fusion. Twenty-five patients underwent a laparoscopic procedure and 22 an open mini-ALIF. Three laparoscopic procedures were converted to open ones. For perioperative parameters only, the operative time was statistically different (P=0.001), while length of postoperative hospital stay and blood loss were not. The incidence of operative complications was three in the laparoscopic group and two in the open mini-ALIF group. After a follow-up period of at least 2 years, the two groups showed no statistical difference in pain, measured by visual analog scale, in the Oswestry Disability Index or in the Patient Satisfaction Index. The fusion rate was 91% in both groups. The laparoscopic ALIF for L5-S1 showed similar clinical and radiological outcome when compared with open mini-ALIF, but significant advantages were not identified, despite its technical difficulty.

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PubMed2003

Efficacy of percutaneous vertebroplasty in the treatment of intravertebral pseudarthrosis associated with noninfected avascular necrosis of the vertebral body.

STUDY DESIGN: A retrospective clinical study on the effect of percutaneous vertebroplasty (PVP) in the treatment of intravertebral pseudarthrosis caused by avascular necrosis of a vertebral body. OBJECTIVES: To evaluate the efficacy of PVP in the treatment of spinal instability associated with avascular necrosis. SUMMARY OF BACKGROUND DATA: Two radiologic features of avascular necrosis of a vertebral body are intravertebral vacuum phenomenon and fluid collection, combined with a collapsed vertebra. These can sometimes result in dynamic instability due to intravertebral pseudarthrosis. A treatment for this instability, associated with avascular necrosis, has not been established. METHOD: Sixteen patients with instability, associated with avascular necrosis of a vertebral body, were treated by PVP. The indicators of the condition included spinal instability associated with avascular necrosis, which was diagnosed by a vacuum phenomenon or by fluid collection in the vertebral body as found from imaging studies. The instability of the vertebral body was confirmed from the dynamic lateral view in both flexion and extension. The anterior body height and kyphotic angle changes between pre- and post-treatment were measured on a lateral radiograph. Plain radiography was used during the follow-up period (8-14 months; mean, 11 months) to assess the vertebral column stability. The pain level of each patient was assessed, both before and after the procedure, using a visual analog scale (VAS), ranging from 0 to 10. Marked or complete pain relief was achieved in eight (50%) patients, and moderate pain relief in six (38%), with the immediate postoperative average pain score reduced from 9.0 to 4.3. The mean corrected angle and vertebral height between pre- and post-treatment were 8.5 degrees and 7.0 mm (P =0.001), respectively. There was no significant change in the kyphotic angle of the treated level during the follow-up period (P =0.711). CONCLUSIONS: Percutaneous vertebroplasty is a reasonable procedure for the treatment of spinal instability associated with avascular necrosis, but not that caused by an infection. PVP was found to be a minimally invasive and effective procedure that provides pain relief and stabilization of spinal instability associated with noninfected avascular necrosis of the vertebral body.

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PubMed2002

Treatment of lower lumbar radiculopathy caused by osteoporotic compression fracture: the role of vertebroplasty.

The authors used vertebroplasty for the treatment of severe lower lumbar radicular pain caused by osteoporotic compression fracture. Patients presented with severe radiating leg pain rather than lower back pain from recent osteoporotic compression fracture of lower lumbar vertebra. Radiologic findings showed osteoporotic compression fracture combined with preexisting stenosis of the intervertebral foramen resulting in root compression. After injection of polymethylmethacrylate into the compressed vertebral body through the pedicle of the symptomatic side, all seven patients experienced dramatic pain relief that lasted throughout the mean follow-up duration of 9.1 months. They conclude that vertebroplasty may be an effective way of relieving radicular pain caused by osteoporotic compression fracture combined with foraminal stenosis.

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