Yoon Kyoung Lee

Transplantation of Human Adipose-Derived Stem Cells in a Rabbit Model of Traumatic Degeneration of Lumbar Discs

OBJECTIVE The purpose of the present study is to assess the possibility of disc regeneration by treatment with adipose-derived stem cells (ADSCs) in a rabbit model of degenerative disc disease, and to evaluate the efficacy of a percutaneous technique for constructing a model of degenerative disc disease in rabbits. METHODS The study sample consisted of 20 mature male New Zealand white rabbits. Intervertebral discs were injured in each rabbit by a percutaneous technique at L2-3, L3-4, and L4-5 under C-arm guidance with a 19-gauge spinal needle. Magnetic resonance images (MRI) were checked at 6, 9, 12, and 15 weeks after injury to evaluate disc degeneration. Nineteen weeks after injury, ADSCs were injected into the L4-5 disc space, with saline injected into the L3-4 disc as a control, using a 21-gauge spinal needle. Histologic confirmations of degenerated discs were performed at 10 and 18 weeks after injury with safranin O and trichrome stains. RESULTS MRI revealed intervertebral disc degeneration from 9 weeks after injury, and full degeneration at 15 weeks after injury, when compared with uninjured control discs. We confirmed the proliferation of ADSCs at the L4-5 level in 10-week rabbits after cell injection. Histologically, the ADSC-injected discs exhibited elevated extracellular matrix secretion and little ossification of damaged cartilage in the nucleus pulposus compared with degenerative control discs. CONCLUSIONS These results suggest that the injection of ADSCs into injured lumbar discs could be an effective treatment for degenerative disc disease by promoting the cartilage regeneration.

Perioperative Risk Factors Related to Lumbar Spine Fusion Surgery in Korean Geriatric Patients

Objective Life expectancy for humans has increased dramatically and with this there has been a considerable increase in the number of patients suffering from lumbar spine disease. Symptomatic lumbar spinal disease should be treated, even in the elderly, and surgical procedures such as fusion surgery are needed for moderate to severe lumbar spinal disease. However, various perioperative complications are associated with fusion surgery. The aim of this study was to examine perioperative complications and assess risk factors associated with lumbar spinal fusion, focusing on geriatric patients at least 70 years of age in the Republic of Korea. Methods We retrospectively investigated 489 patients with various lumbar spinal diseases who underwent lumbar spinal fusion surgery between 2003 and 2007 at our institution. Three fusion procedures and the number of fused segments were analyzed in this study. Chronic diseases were also evaluated. Risk factors for complications and their association with age were analyzed. Results In this study, 74 patients experienced complications (15%). The rate of perioperative complications was significantly higher in patients 70 years of age or older than in other age groups (univariate analysis, p=0.001; multivariate analysis, p=0.004). However, perioperative complications were not significantly associated with the other factors tested (sex, comorbidities, operation procedures, fusion segments involved). Conclusion Increasing age was an important risk factor for perioperative complications in patients undergoing lumbar spinal fusion surgery whereas other factors were not significant. We recommend good clinical judgment and careful selection of geriatric patients undergoing lumbar spinal fusion surgery.

Long-Term Follow-Up Radiologic and Clinical Evaluation of Cylindrical Cage for Anterior Interbody Fusion in Degenerative Cervical Disc Disease

Objective Various procedures have been introduced for anterior interbody fusion in degenerative cervical disc disease including plate systems with autologous iliac bone, carbon cages, and cylindrical cages. However, except for plate systems, the long-term results of other methods have not been established. In the present study, we evaluated radiologic findings for cylindrical cervical cages over long-term follow up periods. Methods During 4 year period, radiologic findings of 138 patients who underwent anterior cervical fusion with cylindrical cage were evaluated at 6, 12, 24, and 36 postoperative months using plain radiographs. We investigated subsidence, osteophyte formation (anterior and posterior margin), cage direction change, kyphotic angle, and bone fusion on each radiograph. Results Among the 138 patients, a minimum of 36 month follow-up was achieved in 99 patients (mean follow-up : 38.61 months) with 115 levels. Mean disc height was 7.32 mm for preoperative evaluations, 9.00 for immediate postoperative evaluations, and 4.87 more than 36 months after surgery. Osteophytes were observed in 107 levels (93%) of the anterior portion and 48 levels (41%) of the posterior margin. The mean kyphotic angle was 9.87° in 35 levels showing cage directional change. There were several significant findings : 1) related subsidence [T-score (p=0.039) and anterior osteophyte (p=0.009)], 2) accompanying posterior osteophyte and outcome (p=0.05). Conclusion Cage subsidence and osteophyte formation were radiologically observed in most cases. Low T-scores may have led to subsidence and kyphosis during bone fusion although severe neurologic aggravation was not found, and therefore cylindrical cages should be used in selected cases.