Dynesys® Dynamic Stabilization System
The Dynesys Dynamic Stabilization System combines the surgical
approach of traditional fusion with the philosophy of dynamic stabilization,
using flexible materials to stabilize the spine while preserving anatomical
structures.
| The result is dynamic stabilization that allows the surgeon to preserve much of the spinal anatomy. It accommodates a familiar surgical approach and minimally invasive techniques in a range of patients -- including those with acute and chronic instabilities caused by degenerative changes in the intervertebral discs.* |
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*For full indications for use, please see Patient Indications below as well as the Dynesys Spinal System Instructions for Use and Surgical Technique Manual.
A More Natural Position
The Dynesys System augments fusion treatment by dynamically stabilizing the affected joints at rest, in flexion and in extension.
Once the devices are attached bilaterally to the affected segments, the dynamic push-pull relationship between spacer and cord stabilizes the joints, keeping the vertebrae in a more natural position.
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| At rest: The Dynesys System supports an intervertebral joint between L4 and L5. | Flexion: Pedicle screws hold the polyethylene cord secure, supporting the affected joint as the spine bends forward. | Extension: The external spacer -- a polyurethane tube -- provides support for the affected joint as the spine bends backwards. |
Preserving Anatomy
Unlike other pedicle-screw devices, the Dynesys System's screws are placed lateral to the facets. As a result, the surgeon is able to preserve more of the facets than can be spared with conventional pedicle-screw placement.
Familiar Surgical Technique
With the Dynesys System, the surgeon can use a minimally invasive procedure or a posterior approach with typical incision and muscle retraction.
The Dynesys LIS instrumentation is designed to preserve soft tissues and minimize exposure in all surgical approaches.
Because this is a new approach to fusion, Zimmer Spine offers comprehensive training and support; ask your Zimmer Spine representative for information on actual training protocols.
How It Works
The Dynesys System begins working as soon as it is in place. Intra-operatively, as the spacer warms from room to body temperature, the cord tension decreases between 25% and 33%. Immediately post-operatively and until fusion occurs, it provides stability similar to a posterior fixation system, with AR, LB and FE motion reduced and stiffness increased from pre-operative levels.
Near-term, the cord tension decreases 25% from its post-operative level. Stiffness also decreases while ROM increases. Long-term, the cord tension remains constant at a 50% reduction from intra-operative levels; AR, LB and FE motion are constrained from pre-operative levels.
Biomechanical Testing
As a completely new implant device, the Dynesys System was subjected to extensive biomechanical testing to measure its strength and durability. Each component was tested separately and then all were tested together in screw-cord and screw-cord-spacer constructs. The results:
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This testing confirmed that, together, the components exhibit robust static and cyclic interconnection strengths.
Patient Indications
The Dynesys System is a pedicle screw fixation system intended to provide immobilization and stabilization of spinal segments as an adjunct to fusion in the treatment of acute and chronic instabilities or deformities of the thoracic, lumbar and sacral spine -- including degenerative spondylolisthesis with objective evidence of neurologic impairment and failed previous fusion (pseudarthrosis).
In addition, the Dynesys System is indicated for use in patients who are:
- Receiving fusions with autogenous graft only
- Having the device fixed or attached to the lumbar or sacral spine
- Having the device removed after the development of a solid fusion mass
Warnings
The safety and effectiveness of the Dynesys System has not been established for spinal indications beyond those stated in the Indications section. The safety and effectiveness of this device for the indication of spinal stabilization without fusion have not been established.
Precautions
Only experienced spinal surgeons with specific training in the use of the Dynesys System should perform the implantation of the system. This is due to the technically demanding procedure presenting a risk of serious injury to the patient. This system should only be used with instrumentation specifically designed for this system.
The Dynesys System is intended to be used with bone graft, which is required to provide additional spinal support. Components of competitive spinal fixation systems should not be used with the components of the Dynesys System and no component of the Dynesys System should be reused or re-sterilized.
The patient should be made aware that a successful result, as defined by reduced pain, increased function and the establishment of solid fusion, is not always achieved in every surgical case. Proper patient selection will greatly affect the results. Patients who smoke have been shown to have an increased incidence of non-union. These patients should be informed of this increased risk and counseled to discontinue tobacco use prior to and immediately after surgery. Obese, malnourished, and/or alcohol abuse patients are also poor candidates for spinal fusion. Patients with poor muscle tone and bone quality, and/or nerve paralysis are also poor candidates for spinal fusion. The use of autogenous bone graft has been shown to provide superior results compared to the use of allograft bone graft material.
In addition to the above specified warnings and precautions, general surgical risks should be explained to the patient prior to surgery.
