Dynamic stabilization as an alternative to spinal fusion

 

Backpain and spinal fusion

Disorders in the vertebral discs (the cartilage like structures located between two vertebrae), which in many cases represent the origin of back pain, can manifest themselves in several disorders such as degenerative disc disease, Spondylolisthesis, Spinal stenosis, Scoliosis, or herniated disc among others. Most of these disorders are characterized by a destabilization of the spine and a more or less chronic back pain, which can make everyday tasks more difficult and reduce the quality of life of people who suffer from it^1,2

Back pain is known to be one of the leading causes of disability worldwide, and despite the heterogeneity of its causes, there is an important portion of the patients suffering from it which can benefit from surgical approaches to stabilize the affected spine^3, Already in the early twentieth century, a surgical procedure called spinal fusion began being used to treat spine deformities, and it was found that not only did the procedure correct the deformity, but that it also reduced the patient's low back pain⁴. Ever since, spinal fusion has been most commonly performed to relieve the pain and pressure on the spinal cord that results when a disc wears out. There are many types of spinal fusion techniques, but the main principle consists in using bone grafting —it can be harvested from the patient (autograft), a donor (allograft), or artificial bone substitutes may be used— to “weld” two or more vertebrae. This prevents the movement of the affected spine segment and alleviates the strain in the degenerated discs.

 

Spinal fusion disadvantages

Although this procedure has been used for many years, it comes with some drawbacks. The most obvious disadvantage is the reduction of the spine mobility due to the fusion of previously independent vertebrae. Because the normal motion range of the spine is compromised, more stress is placed on the vertebrae above and below the fused segments. As a result, long-term complications include degeneration of these adjacent spine segments. Moreover, the rigidity of these neighbouring segments tends to increase, and additional vertebrae may even eventually fuse.

The use of bone grafts also represents possible complications, specially when using autografts. The bone must be harvested from the patient’s body and this represents an additional procedure, with the complications that this implies.

 

Improvements and alternatives to spinal fusion – Dynamic Stabilization

In the decade of the seventies, a relatively new procedure called pedicular fixation (introduced by Prof. Raymond Roy-Camille in the sixties), was customized in order to be incorporated into spinal fusion procedures⁵. This technique improved the anchorage of the screws to the spine and facilitated the fusion process⁶.

In the decade of the nineties, doctors were looking for an alternative to spinal fusion. Some new options appeared which favoured a dynamic stabilization instead of the rigid equilibrium provided by the fusion technique. The dynamic stabilization aimed to provide the required stabilization using implants which gave support to the spinal column, while allowing the natural movement of the spinal column ^7,8.

The most effective of these approaches, from which SpineShape evolves after improvements and refinements, was a technology developed in Switzerland described for the first time in a 1999 publication by S. Freudiger et al.⁹. This technology has been used ever since, and the current SpineShape System IV model has been used in more than 700 procedures in Switzerland in the last 4 years.

 

How does it work?

Instead of fusing the bone to create a rigid, stable structure, an implant is inserted which provides stabilization for the misplaced or degenerated discs¹⁰.

Screws are located into the spinal column in the pedicular fixation fashion, and a flexible rod connects them in order to provide the traction necessary for the treatment. Spine Shape provides three different levels of rod stiffness and various designs which allow the surgeon to choose the best option for each case.

 

What are the advantages of Dynamic Stabilization?

The SpineShape system of dynamic stabilization reduces both the operation time and the recovery time, facilitating the rehabilitation process. The pain is greatly reduced if not completely eliminated, and this results in a drastic reduction of painkillers prescription. On top of the pain elimination, dynamic stabilization preserves the spine mobility, allowing the patient to regain complete mobility after the recovery.

The preservation of the mobility in the operated discs and the reorganization of the pressures in the spine has two main effects: on one hand, degeneration of the discs and the spinal column is reduced or postponed, and, in some cases, the affected discs can even regenerate. On the other hand, the dynamic stabilization also reduces the strain in the adjacent segments of the column. This alleviates one of the main drawbacks of spine fusion, which is the degeneration of these adjacent spine segments.

 

 

BIBLIOGRAPHY

 

Articles

 

1.     Subacute and Chronic Low Back Pain: Surgical Treatment. Chou, Roger et al.

2.     Mechanisms of low back pain: a guide for diagnosis and therapy. Allegeri, Massimo et al.

3.     Decision making in surgical treatment of chronic low back pain: the performance of prognostic tests to select patients for lumbar spinal fusion. Willems, P. et al

4.     Spinal fusion surgery: A historical perspective. Tarpada, Sandip P.  et al.

5.      Pedicle screw fixation in spinal disorders: A European view. N. Boos et al.

6.     The History of Vertebral Screw and Pedicle Screw Fixation.  Kabins, Mark B et al.

7.     A Short History of Posterior Dynamic Stabilization. Gomleksiz, Cengiz.

8.     Dynamic stabilization of the lumbar spine confirmed on a new lumbar spine simulator in vitro S. Freudiger et al.

9.     Dynamic stabilization versus fusion for treatment of degenerative spine conditions. Chou, Dean.

10.  Role of Dynesys as Pedicle-Based Nonfusion Stabilization for Degenerative Disc Disorders. Anand, Neel et al.

 

Websites

https://orthoinfo.aaos.org/en/treatment/spinal-fusion/

https://www.spine-health.com/treatment/spinal-fusion/spinal-fusion-a-quick-history

https://www.mayoclinic.org/diseases-conditions/back-pain/symptoms-causes/syc-20369906