Purpose
To verify the validity of a pedicle screw based posterior dynamic stabilization(PDS).
Materials and Methods
At first, theoretical evidences were reviewed and presented the objections against PDS. The answers were investigated by reviewing the development concepts and clinical evidences of each device.
Results
There is no PDS which has been approved as a dynamic stabilizer by US FDA yet. Dynesis^® and Isobar TTL^® were approved as a fusion adjunct. AccFlex^® and CD-Horizon Legacy PEEK rod^® were approved as a single level posterior lumbar interbody fusion adjunct. Dynesys^® is undergoing an FDA IDE study as a non-fusion dynamic stabilizer. Patient’s symptoms were improved, however, there were scarce controlled studies with simple decompression or fusion surgeries. Furthermore quantitative comparison of improvement was impossible because the subjects were not homogenous. Adjacent segment degeneration was not prevented. Stabilized segments showed further degeneration and there wasn’t a case which showed regeneration of disc. Most of segments were fused or became more stable than physiologic motion and allowance of the PDS. Device failure was reported as 5-21%, however most cases were asymptomatic.
Conclusion
In the light of current evidences, PDS is considered not to prevent the problems which were engendered by fusion surgeries. It is not convincible that PDS has a niche between decompression and fusion surgeries.

Lumbar spinal stenosis is one of the degenerative diseases which have increasingly grown, as the nation is transitioning to an aging society. Even though medication is readily available as treatment for lumbar spinal stenosis, surgical treatments can be considered if symptoms are severe. The most basic operation, laminectomy and decompression, alone, can bring about improvements of symptoms by alleviating the pressure of the nerve root, however if instability is evident on the radiograph or during surgery, spinal fusion will be performed, and will yield favorable results. On the contrary, it is also common knowledge that spinal fusion can give rise to a variety of complications afterwards. New surgical procedures and apparatuses have been developed and used in clinical practices in order to overcome these complications. One of these new concepts is posterior dynamic stabilization. The purpose of posterior dynamic stabilization is to enable the spine to adjust so that, by limiting the movement to the direction which causes the pain, patients can feel at ease. Until recently, interspinous devices have been developed and applied in clinical practices in order to improve the symptoms of patients. The device is inserted after decompression of the nerve root in between the spinous processes of the lumbar part, where the symptom is present. By doing so, it not only limits the extension (without impacting flexion, axial rotation, and lateral bending) but also, alleviates the load on the facet joint by playing a role as a shock absorber. However, it is also true that the practice of this surgery has been limited due to the reports showing that; halo formed between the contact surface of the bone and the metal device might be the cause of pain; and according to a follow-up survey, fractures of the spinous process, breakaway of apparatus and post-operative complication such as kyphosis may be present. This paper will investigate the usefulness of these devices again by looking at the fundamental biomechanical effect of interspinous devices and analyzing the thesis which has been previously published.

Purpose
To compare change in biomechanical function at operated and adjacent segments and clinical results after inserting three different designs of cervical artificial arthroplasty devices.
Materials and Methods
Retrospective analysis was performed for 60 patients who had undergone single level cervical artificial arthroplasty in authors’ hospital from November 2003 to January 2010. Bryan, Prestige LP and Prodisc– C artificial discs were used in 34, 17 and 9 patients respectively. We compared preoperative and postoperative biomechanical function of operated and adjacent segments radiographically and clinical results using VAS and NDI.
Results
Biomechanical results showed as follows: range of motion(ROM) of operated and overall cervical spine was well maintained postoperatively regardless of type of devices; Prodisc – C showed statistically significant recovery of sagittal alignment at the operated segment compared to preoperative status(p=0.021); adjacent level just inferior to the operated segment showed decrease in postoperative ROM with Bryan(p=0.000); anterior intervertebral height also decreased at that segment(p=0.001); no difference showed with VAS and NDI in the three artificial disc devices.
Conclusion
Clinical results of cervical artificial arthroplasty did not show significant difference during the follow-up period, but there were statistically significant changes in biomechanical function. Therefore, adequate selection of disc device is important in cervical arthroplasty.

Introduction
Recently, minimally invasive lateral approach for the lumbar spine is revived and getting popularity under the name of XLIF or DLIF by modification of mini-open method using sequential tubular dilator and special expandable retractor system. Purposes: The purposes of this study were to introduce the mini-open lateral approach for the anterior lumbar interbody fusion (ALIF), and to investigate the advantages, technical pitfalls and complications & to provide basic knowledge on XLIF or DLIF
Materials and Methods
Seventy-four patients who underwent surgery by the mini-open lateral approach from September 2000 to April 2008 with various disease entities were included. Blood loss, operation time, incision size, postoperative time to mobilization, length of hospital stay, technical problems and complications were analyzed.
Results
With this approach, we can reach form T12 to L5 subdiaphragmatically. The blood loss and operation time of patients who underwent simple ALIF were 61.2 ml and 86 minutes for one level, 107 ml and 106 minutes for two levels, 250 ml and 142.8 minutes for three levels, and 400 ml and 190 minutes for four levels of fusion, respectively. The incision sizes were on average 4.5cm for one level, 6.3 cm for two levels, 8.5 cm for three levels and 10.0 cm for four levels of fusion. The complications were retroperitoneal hematoma in two cases, pneumonia in one case and transient lumbosacral plexus palsy in three cases.
Conclusion
The mini-open lateral approach is simpler & safer than XLIF or DLIF with very short learning curve. Trial of mini-open lateral approach would be helpful before trial of XLIF or DLIF. However, special attention is required to complications such as transient lumbosacral plexus palsy.

Purpose
The purpose of this study is to decrease the frequency of the perioperative complication and improve the clinical outcomes of multilevel lumbar degenerative disease by multilevel minimally invasive transforaminal lumbar interbody fusion.
Materials and Methods
317 patients(Minimally invasive transforaminal lumbar interbody fusion : 161, Conventional open surgery : 156) were followed up for more than 1 year. The age of each patient, the amount of intraoperative blood loss, the postoperative drainage, the transfusion requirement, surgery time, using of Intensive care unit, ambulation day, admission day and perioperative complications were investigated and analyzed.
Results
Minimally invasive transforaminal lumbar interbody fusion was found to have a less blood loss, less using of Intensive care unit. And as the levels of union increase, disparities were increased(p<0.05). But, surgery time of Minimally invasive transforaminal lumbar interbody fusion was longer, and as the levels of union increase, disparities were increased(p<0.05).
Conclusions
Multilevel Minimally invasive transforaminal lumbar interbody fusion can be the better way, If surgery time of Multilevel Minimally invasive transforaminal lumbar interbody fusion can be reduced.

A 45 year-old male was brought to our hospital with severe back pain and motor, sensory impairment in both lower extremities. He had no underlying diseases including coagulapathy. Motor weakness below both hip joint and decreased sensory below T12 dermatome, voiding dysfunction were examined. The MRI showed a spinal subdural hematoma at the thoracolumbar region, which was extremely rare. Medical treatment was applied without surgical interventions. After two weeks, motor weakness, sensory impairment, and voiding dysfunction were improved. And he returned to his daily activities. We present this case and literature reviews because traumatic spinal subdural hematoma is an extremely rare disease and the condition was treated successfully in conservative manner.