Purpose
of study: The purpose of this study is to understand the biomechanics of interspinous devices in lumbar spinal surgery and to review the effectiveness of the devices for lumbar spinal stenosis through recent related articles.
Materials and Methods
Medical databases were searched for the key words of interspinous device and lumbar spinal stenosis using PubMed from 2010 to the present.
Results
Several studies have shown sustained symptomatic improvements after interspinous device insertion. However, most of the prospective, randomized, double-blinded studies have shown that it is not superior to conventional laminectomy from a statistical perspective. Furthermore, interspinous device insertion has been shown to have a higher reoperation rate and to be less cost effective.
Conclusions
A large prospective cohort study with a longer follow-up period comparing decompressive surgery alone versus interspinous device insertion for the treatment of lumbar spinal stenosis is needed to conclusively determine whether the interspinous device is beneficial.

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.