Purpose
Total en bloc spondylectomy (TES) is one of curative surgical methods used for solitary spinal tumors, if indicated. However, TES is a complex technique and prudent preparation is mandatory. However, elective TES is not always possible for patients with neurological and mechanical spinal instability. In such situations, percutaneous pedicle screw fixation, with the purpose of stabilizing the spine and gaining time before TES, may be used.
Methods
The first patient was a 29-year-old female who visited the emergency room (ER) due to progressive paraparesis (motor grade III/V) and back pain. Magnetic resonance imaging (MRI) showed compression of the spinal cord by a tumor and a collapsed L1 body. The second patient was a 23-year-old female who came to the ER with severe back pain. MRI revealed compression of the spinal cord by a collapsed T11 vertebral body and a tumor. In both cases, neurological and mechanical instabilities were caused by a primary vertebral tumor. For both patients, TES was an optimal surgical technique, but TES was not possible on an emergency basis.
Results
In both patients, percutaneous pedicle screw fixation, distraction, and biopsy were performed on an emergency basis. Subsequently, weakness and/or pain improved in both patients. Elective TES operations were successfully performed 3 weeks or 1 month later.
Conclusions
If TES is indicated, but preparation time is insufficient, tentative spinal stabilization with a percutaneous technique may be utilized before TES. However, considering the need for additional surgery, skin incision, and cost, this surgical strategy should be selectively applied.

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.