Dynesys
The Dynesys system is designed to re-stabilize unstable segments without involving the intervertebral discs and facet joints; the segments remain mobile within a controlled range. The guiding principle of the system is the ability to create load shring and restoration of disc height, not necessarily motion preservation because the system is so rigid.
Materials:
The Dynesys is a pedicle screw system for mobile motion, consisting of titanium alloy screws connected by an elastic synthetic compound, controlling motion in any plane. The screws are made of the Ti-Al-Nb forge alloy Protusal™ 100, Polycarbonate spacers made of Sulene™ PCU and a polyethylene terephthalate cord.
Sizes:
The dynesys has many compenents that come in many different sizes.
Surgical Procedure:
First the posterior spine segment is exposed. The pedical screws are inserted in a standard pedicle screw system procedure. Then the stabilizing cords are put in place. The spacers are then inserted segement by segment. The spacer size is cut to fit each segment and then the stabilizing cords are tightened seperately. The facet screw is then tighted which fastens the ligament to the pedicle screw. A special instrument is used to add tension to the stabilizing cord. The stabilizing cord is then cut and the surgical wound is closed.
Indications:
Unstable segmental conditions, mainly combined with:
- Central spinal stenosis
- Grade I spondylolisthesis
- Isthmic spondylolisthesis
- Radiculopathy
- Spondylarthrosis with primary discopathy
- Spondylarthrosis with discopathy hypo-mobile
- Spondylarthrosis with protrusion/prolapse
- Spondylarthrosis with discopathy hoper-mobile and functional instability
- Spondylolisthesis
- Degenerative discopathy
- (Disc herniation)
Effect:
The Dynesys system reduces movement both in flexion and extension. This design produces maximal unloading of the disc, whilst allowing a restricted range of movement.
Studies:
In one study done by Stoll, Dubois, and Schwarzenbach, the Dynesys was found to sucessfully provided support and stability to unstable sections of the spine. They concluded that the system is an effective alternative to fusion.
Dr. J Huber presented clinical data on Dynesys from centers in Switzerland and France. It was used on seven patients with disc hernia, twenty patients with disc degeneration disease, and fifty patients with lumbar spinal stenosis. The study concluded that is is very effective system for reducing radiculopathy.
Success Rates:
Dr. Huber's study gave results of sixty on the Oswestry Scoring system before the Dynesis system for the LSS patients, and then a score of twenty after the operation. This seems to suggest the system is effective for the treatment of lumbar spinal stenosis.
Availability:
This product is available everywhere in the world except in the United States. There is currently an IDE study for the Dynesys system in order for possible approval for sale in the US eventually.