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Study Design: A retrospective radiologic analysis of 34 patients Objectives: To evaluate the factors influencing the radiographic degenerative changes in the adjacent segments in one-level ACDF Summary of Literature Review: There is a 25% incidence of adjacent segment degeneration after 5 years. Materials and Method: From 2002 to 2005, 34 patients (male 23, female 11) underwent anterior cervical spine fusion using a cage or bone block for degenerative cervical spine. The mean age of the patients was 51 years and the mean follow-up period was 24 months. The degenerative findings of the upper and lower adjacent segment were measured from the pre-operative MRI. The fused segment curvature, disc heights of the adjacent segments, displacement of the vertebral bodies and angular mobility in the adjacent segments were measured from the pre-operative and final follow-up lateral views in the neutral position, in both flexion and extension. Results: Degenerative changes in the adjacent segments were observed in 19 of the 34 patients. The group with degenerative changes showed significantly more lordotic angular loss of the fusion segments (11.9±3.1˚) at the follow-up observation than the group with no degenerative changes (9.0±1.1˚) (p=0.04). The group with degenerative change showed a significantly larger increase in disc height of the fusion segments (2.8±0.2 mm) at the follow-up observation than the group with no degenerative changes (2.2±0.3 mm) (p=0.02).The group with a Grade IV or higher level of pre-operative disc degeneration showed more degenerative changes in the adjacent segments than those with Grade III or lower. Conclusions: It is important to preserve the lordotic angle of fused segments and avoid excessive increases in disc height. The recurrence of the neurological is not associated with the preoperative adjacent segmental degenerative changes in ACDF.

Study Design: A retrograde study of metal failures at thoracolumbar spinal fractures fixed using pedicle screws. Objectives: The predictability and usefulness of the McCormack's classifications for metal failures was compared with Magerl’s classifications. Summary of Literature Review: The load sharing classification was introduced to predict metal failure after short-segmental pedicle screw fixation by McCormack. However, its reliability is uncertain. Materials and Methods: From July 2000 to July 2003, this study examined the plain radiographs and CT images of 31 out of 46 patients who underwent posterior stabilization using pedicle screws for thoracolumbar fractures and could be followed up at least 1 year. Fractures were classified utilizing Denis’s, Magerl’s, and McCormack’s systems. Results: As a result of analysis of relation between metal failure and classification system by Magerl or McCormack, there was no significant difference in its distribution. There was no correlation between the fixation range and metal failures in type C3 fractures, but there was a correlation between short fixation and metal failures in rotational burst fractures in short fixation. Conclusions: In order to prevent metal failures after fixing thoracolumbar spinal fractures by pedicle screws, the stability should be evaluated using Magerl’s classification and McCormack’s total score. In addition, in cases of type C3 fractures according to the Magerl’s classification, reconstructions should be carried out with a long segment fixation or anterior supporting bone grafts, particularly when McCormack’s total score is greater than 7.

Study Design: A Retrospective study Objectives: To analyze the causes of revision arthrodesis for the degenerative changes at the adjacent segment after lumbosacral fusion for degenerative lumbar diseases. Summary of Literature Review: Revision arthrodesis is quite common. However, there is some controversy regarding the causes and risk factors. Materials and Methods: Twenty cases who had undergone revision arthrodesis after lumbosacral fusion were examined. Preexisting degenerative changes to the adjacent segment, location of the adjacent segment and extent of fusion, as well as changes in lumbar lordosis were observed in primary arthrodesis, and the relationship between the changes in the adjacent segment degeneration were analyzed in terms of the area of residence, activity level and living pattern of the patients. Results: Preexisting degenerative changes in the adjacent segment were observed in 14 cases and degenerative changes developed at the proximal junction in 19. Multiple segment fusion were performed in 13 cases during primary arthrodesis, 9 cases developed degenerative changes at the proximal junction. Fifteen cases with abnormal postoperative lumbar lordosis demonstrated adjacent segment degeneration. Sixteen cases living in the countryside and 15 cases with a history of severe physical labor after the primary operation showed degenerative changes in the adjacent segment before secondary arthrodesis. Conclusion: The causes of revision arthrodesis for the degenerative changes at the adjacent segment are believed to be preexisting degenerative changes in the adjacent segment at the proximal junction, loss of lordosis after primary fusion, and severe physical labor from living in the countryside

Study Design: Retrospective study Objective: To analyze the treatment results of vertebroplasty in patients who suffered osteoporotic compression fractures during conservative treatments for pre-existing degenerative lumbar disease. Summary and Literature Review: Whilst spinal fusion has shown satisfactory clinical results, solid fusion has been reported to accelerate the degenerative changes at the unfused adjacent levels. Therefore, the level of spinal fusion in patients with compression fractures and pre-existing degenerative lumbar disease is controversial. Few studies have evaluated the outcomes of spinal fusion and adjacent segment vertebroplasty. Materials and Methods: A retrospective review was carried out on 28 patients who suffered the osteoporotic compression fractures during conservative treatment for pre-existing degenerative lumbar disease. Posterolateral fusion and vertebroplasty were performed for degenerative disease and compression fractures. The average fusion level was 1.82. The mean compressed vertebral bodies were 1.68. The radiology results were evaluated to determine the progression of the compression rate and fractures in the adjacent segment. The clinical results were evaluated using the Denis pain scale for compression fractures and Katz satisfaction scale for degenerative lumbar disease. Results: The average compression rate was 30.2% preoperatively, 21.4% postoperatively, and 24.6% at the final follow-up. There was no fracture in the adjacent segment. Clinically, the preoperative Denis score was P3 and P4 in 8 and 20 patients, respectively. On the other hand, the postoperative Denis score was P1, P2 and P3 in 8, 19 and 1 patients, respectively. In regard to degenerative diseases, the overall satisfaction was 82.1%. Conclusion: The stability of fracture sites in vertebroplasty of patients with pre-existing lumbar disease was confirmed. However, further compression of the fractured vertebral body was observed after vertebroplasty in long fusion. Therefore, a followup study of more cases will be necessary to confirm the changes in the vertebroplasty site.

Study Design: Retrospective study Objective: To evaluate the factors affecting metal failure and screw loosening of short-segmental (1- or 2-segmental) monoaxial or polyaxial screw fixation for degenerative lumbar disease. Summary of Literature Review: There was a report on metal failure and screw loosening in short-segmental monoaxial and polyaxial screw fixation in degenerative lumbar disease. Materials and Methods: This study examined 227 cases who underwent short-segmental transpedicular screw fixation and vertebral fusion for a degenerative lumbar. Results: Metal failure of transpedicular screws was detected in 6 cases, 3 each in groups A and B. Screw loosening occurred in 16 and 43 cases in group A and B, respectively. Both groups had a similar incidence of spinal stenosis with instability and spondylolisthesis. The failure rate and screw loosening according to the fusion level was also similar. The failure and screw loosening rates was higher in the cases who did not undergo PLIF than in the cases who underwent PLIF but the difference was not statistically significant. Conclusion: The metal failure and screw loosening rates after transpedicular screw fixation and spinal fusion procedures for degenerative lumbar diseases using monoaxial screws and polyaxial screws were similar.

Study Design: Retrospective study Objectives: This study examined the post-operative results of interlaminar percutaneous endoscopic lumbar discectomy (PELD) with or without endoscopic laminotomy in lumbar disc herniation. Summary of Literature Review: In addition to the technical feasibility, the indications of PELD surgery are usually the same as those for open discectomy. Materials and Methods: From January 2005 to August 2006, 62 cases treated with PELD using an interlaminar approach due to lumbar disc herniation were examined. The mean age of the subjects was 40.1 years (18-70) and the mean follow up period was 32.6 months (24-44). Thirty-four and 28 herniated discs were extracted from L4-L5 and L5-S1, respectively. The clinical results were evaluated using MacNab’s criteria. Results: The herniated discs were accessible in all cases. Excellent and good results were obtained in 85% (53 cases) of patients but 15% of patients (9 cases) showed unsatisfactory results or needed revision. There were 4 cases of incomplete removal, 2 cases of recurrence and 4 cases of persistent low back pain due to associated degenerative pathologies. Additional surgery was required in 7 cases which were open discectomy in 5 cases (3 cases of 4 incomplete removal and 2 of recurrence). There was one case of PLIF and 1 additional decompression. Cauda equina syndrome occurred in one case who underwent subsequent wide decompression and open discectomy. Conclusions: interlaminar PELD using endoscopic laminotomy is an effective method for treating lumbar disc herniation with moderate up and down migration. The clinical success rate can be improved by selecting patients with accessible discs and excluding those with an associated pathology.

Study Design: A retrospective study. Objectives: We report the efficacy of the entry point and approach angle of a working cannula using preoperative prone abdominal computer tomography (PACT). Summary of Literature Review: To date, there are no reports on the entry point and approach angle of a working cannula when performing transforaminal percutaneous endoscopic lumbar discectomy (TPELD) with consideration of the individual anatomic variations and characteristics of herniated disc and surgical instruments. Materials and Methods: Cases of herniated intervertebral discs from L4-5, who have previously undergone PACT before TPELD, were included. A total of 25 patients were observed over a 1 year period. The entry point and approaching angle of the working cannula with PACT were calculated, and the results were applied to the TPELD. The clinical results were assessed 1 month after surgery using the VAS, ODI and MacNab criteria, and were confirmed by a radiology and MRI examination. Results: The preoperative measured data using PACT showed that the mean approaching distance and mean approaching angle of the working cannula were 12.4 cm and 75.4 degree, respectively. The VAS improved from a mean of 8.1 preoperatively to a mean of 2.3 12 months after surgery. The ODI improved from a mean of 59 preoperatively to a mean of 24 at 12 months after surgery. According to the MacNab criteria, all patients were classified as either excellent and good during the follow up periods. The extruded disc of all patients had been well removed according to the MRI scan performed 1 month after surgery. Conclusions: The scientific approach method using PACT based on the characteristics of patients and surgical instruments can be performed easily and accurately, and access and decompress the extruded disc directly.

Study Design: Retrospective study Objectives: To compare the surgical results of microendoscopic discectomy using a tubular retractor with those of a conventional discectomy for lumbar herniated nucleus pulposus. Summary of Literature Review: Minimally invasive approaches to the lumbar spine have been attempted with success over the past 25 years. Materials and Methods: This study examined 36 cases who underwent lumbar discectomy using a tubular retractor and microendoscopy (Group A) and 30 cases who underwent a conventional discectomy (Group B). The operating time, intraoperative blood loss, postoperative hospital stay were recorded. The clinical results were assessed using the Korea Version Oswestry Disability Index (KODI), and the radiological results were evaluated from changes in disc height. Results: The patients in Group A had a longer operation time(mean, 95.56±23.57 minutes vs 81.17±35.30 minutes, p=0.062), less intraoperative blood loss (mean, 58.61±97.08 cc vs 161.00±88.64 cc, p=0.001) and a shorter hospitalization stay (mean, 8.22 ±4.99 days vs 17.33±10.98 days, p=0.001) than group B. There was significant improvement in the mean KODI score for Group A; 6.36±7.18 and Group B; 5.97±5.14. However, there was no significant difference in the pain improvement (mean, 1.14 ±1.15 vs 1.30±1.06, p=0.559) and walking index (mean, 0.25±0.44 vs 0.30±0.47, p=0.656). In terms of social life, Group A had better results (mean, 0.20±0.48 vs 0.67±1.01, p=0.018). The disc height according to radiography decreased from 8.44±1.98 mm to 7.40±1.59 mm in Group A and 9.07±1.93 mm to 7.67±1.90 mm in Group B, but there were no statistical differences in the changes in disc height between the two groups (p=0.143). Conclusion: Microendoscopic discectomy is an effective procedure with good outcomes in treating lumbar disc herniation that allows less tissue trauma, compared with conventional open discectomy.

Spontaneous spinal epidural hematomas without any risk factors, such as spinal tap, trauma, pregnancy, bleeding diathesis, vascular malformations, hypertension, etc. are relatively rare clinical entities. In addition, the clinical suspicion is quite difficult because there are various clinical symptoms according to the size and location of hematoma. However, the speed of diagnosis and initiation of the appropriate treatment are important because the outcome for patients is usually determined by the location and degree of neurological deficits and the duration of dural compression. We report the diagnosis and treatment of spontaneous spinal epidural hematoma in this case with a review of the relevant literature.

Posterior epidural migration of a sequestrated intervertebral lumbar disc with cauda equina syndrome is quite rare. This paper reports two unusual cases of posterior epidural migration of a sequestrated intervertebral lumbar disc with cauda equina syndrome to emphasize the importance of early diagnosis and complete decompression.

Displaced fractures of the upper sacrum are a rare type of high energy injury, such as a fall, with similar neurological symptoms and fracture patterns. The authors treated 4 patients with these fracture patterns surgically or conservatively and followed them up for at least 1 year. We report these 4 cases with a review of the relevant literature.

Patients with Crowned dens syndrome typically present with severe neck pain and have calcification around the axial odontoid process on radiographs. To our knowledge, Crowned dens syndrome is unreported in the Korean literature and the clinical features remain unclear. We present Crowned dens syndrome as a cause of acute cervical pain and review the literature.

Upper cervical spine injuries, including atlantooccipital articulation, are being recognized more commonly and there is an increasing number of reports of patients surviving with injuries previously thought to be fatal. The bony elements of the upper cervical spine consist of the occiput, atlas and axis. The nature of their articulations provides no inherent stability, but rather relies on ligaments to maintain the structural integrity. Some upper cervical injuries, occipitocervical injuries, and isolated midsubstance transverse ligament ruptures, are usually unstable and frequently result in neurological injury or death. Therefore, these injuries warrant early instrumented posterior arthrodesis. Most upper cervical spine injuries can be treated non-surgically and heal readily. Implementation of a diagnostic algorithm consisting of screening parameters gathered from the plain radiographs as well as routine CT and MRI scans in high risk patients should reduce the occurrence of missed injuries.