Dynamic Stabilization of the Lumbar Spine

Chronic lower back pain is a very common, significant, and costly health problem in the entire world. It is estimated that more than ten million people in the U.S. alone suffer from chronic back pain at any a given time. The annual prevalence of lower back pain is in the range of 15-45% of the population. Chronic back pain can be debilitating, interfering with one’s ability to work and enjoy recreational activities. It is the most common activity-limiting condition affecting people under the age of 45.

More than 150,000 lumbar fusions are performed each year to immobilize selected vertebrae. It is understandable that we need other treatments for people with pain who are not candidates for fusion. Consequently, millions of people aged 18 to 34 are destined to spend the next years living with back pain if left untreated.Spine specialists all over the world are looking for new approaches to treat low back pain sufferers.

Barcelona Neuroinstitute has found a new and cutting-edge non-fusion alternative and tested it in more than 1000 patients since 2004. It is a pedicle screw-based Dynamic Stabilization System for the lumbar spine.Our team is an expert in motion preservation alternatives to fusion. We are dedicated to providing patients with the highest level of service and expertise, using new technologies like Mazor robotics assistance, intraoperative 3D imaging and neurophysiological monitoring.

 

What is Dynamic Stabilization?

Dynamic stabilization is a non-fusion, motion preservation procedure that is used to treat intolerable low back pain, most commonly associated with degenerative disc disease (DDD). Dynamic stabilization of the lumbar spine procedure uses pedicular screws attached to a flexible rod so that the spine can be stabilized with some retention of motion and no bone fusion is required.

The screws are connected with rope (to prevent excessive extension) and plastic tubes (to prevent excessive compression). It is oriented to return the spine’s movement as close as possible to its normal range of motion, when hypermobility situations have occurred. The system has a significant effect in achieving a more evenly distribution of loads across different structures of the spine.

Degenerative disk disease affects the ability of nucleus to bear compressive loads, and consequently more load is transferred to the peripheral regions of the disk and annulus, several studies confirmed this abnormal load distribution in degenerative disks. It has been proposed that asymmetrical load distribution rather than abnormal motion was the main cause of mechanical low back pain. The presence of high load zones has been described as the “stone in the shoe” theory,

So dynamic stabilization mechanisms of pain control are directed to the uneven load distribution in DDD and instability (hypermobility) of the segment with DDD. Normal biomechanical direction and range of motion include flexion (bending forward), extension (bending backward), lateral bending (right and left side bending), torsion (axial rotational movement), and limited longitudinal elongation and compression (so-called “shock absorber” function), this last function is related to the nutrition mechanisms for the intervertebral disc. Dynamic stabilization recovers this shock absorption function, by means of the flexible spacer that acts as a real shock absorber devise. This function has been occasionally related to a recovery of the high intensity signal (normal pattern) in the affected disc.

Dynamic stabilization is the technique of choice for patients that are interested in having non-fusion and motion preservation procedures for the lumbar spine. These are usually young patients, or middle age patients with an objective of been able to return to active way of life and sports.

The origin of back pain is most commonly associated with degenerative disc disease but can also be associated with lumbar facet disease. The facets are a paired set of joints that are present at every level in the spine between the vertebrae. Dynamic stabilization devices treat pain caused by both degenerative disc and facet disease by supporting and controlling the motion around the painful segment and discharging the load in both structures.

 

Reasons to Prefer Dynamic Stabilization over Spine Fusion and lumbar artificial disk replacement (ADR).

These reasons do not mean that Barcelona Neuroinstitute is not performing spine fusion surgery in the cases where is indicated as well as ADR surgeries.

  • Motion preservation in the operated segment.
  • Any spinal fusion even if done technically correctly can result in failure of fusion, which we call pseudoarthrosis. Failure of fusion often results in poor outcomes and often requires additional surgeries.
  • Dynamic stabilization avoids a bone graft donor site, which is another advantage over the fusion methods. As well as allograft infrequent disease transmission risks.
  • Fusion surgeries take longer and involve greater blood loss than dynamic stabilization.
  • Anterior approach for ADR surgery has potential major complications that are not present in posterior approaches
  • Dynamic stabilization is performed through Wiltse approach that is a muscle preserving technique.
  • Hospital stay is shorter than in fusion or ADR surgeries.
  • The average time for postoperative activity reduction is approximately 3-4 months; whereas, a dynamic stabilization patient restarts activity in approximately 4-6 weeks. Total recovery time will be dependent on the healing process and overall health of each patient.
  • Some fusion patients may develop problems in adjacent levels of the fusion, called ‘adjacent segment disease’. Once two spinal segments have fused, extra stresses are transferred to the discs above and below the fusion. These segments tend to wear out more quickly, which can necessitate additional surgical procedures down the road. This is especially problematic in younger, more active patients. Although we can’t say this doesn’t happen in dynamic stabilization patients, it is much less common (around 50% less).
  • The fusion process and ADR surgery causes irreversible changes to the spine, whereas dynamic stabilization is a reversible process, and theoretically the rods and screws could be removed without any irreversible changes. It is not compromising future surgical options as fusion and ADR do.
  • Dynamic stabilization can treat disk and facet pathology, and ADR is contraindicated in the presence of facet degeneration.
  • Using a posterior approach concomitant pathology needing decompression can be done without the need of two approaches, as can be the case with ADR surgery.

Who is a Candidate for Dynamic Stabilization?

The dynamic stabilization surgery may be suitable for you if:

  • Non-surgical methods have failed to achieve relief of your low back pain and a return to normal activities.
  • You have an active lifestyle and a strong desire to maintain or resume that lifestyle.
  • Your age is not a limitation; provided your health is good.
  • Your MRI shows black discs or other signs of DDD, retrolisthesis, spinal canal stenosis, herniated disk, adjacent segment disease, spondylolisthesis of degenerative type.
  • BARCELONA NEUROINSTITUTE’s neurosurgeons recommend dynamic stabilization of the lumbar spine after a complete evaluation from the clinical and imaging perspective. The procedure can be performed in several levels but best results are obtained in patients needing to treat 1, 2 or 3 levels.
  • You can expect a control of your pain and a return to previous work or sport activities in 87 %.

Disadvantages of dynamic stabilization of the lumbar spine

With dynamic stabilization, there are also concerns regarding the possibility of the stabilization device loosening or braking over time. The softening of bones or noticeable bone loss can also increase the risk of a failed outcome. After our experience in more than 1000 dynamic stabilization procedures screw loosening is radiologically detected in 7% of cases and broken screws in 2,5% of patients. But many remain asymptomatic and revision surgery is needed in only 3,5% of the patients.

The amount of stiffness required in an individual patient depends on the underlying pathology, sex, body constitution, level of the lumbar spine and concomitant surgical procedure needed. This issue of patient-specific requirements and the potential need to customize implants based on intraoperative findings can now be addressed by the different dynamic stabilization available with different rigidity. Also, some available systems provide the surgeon with the ability to perform a nonfusion, or a combination hybrid construct (fusion + dynamic stabilization).

Although combination of the two types of motion preservation technology ADR and dynamic stabilization may be an attractive option, it has not been tested. Kinematic data suggests that such a combined construct may potentially result in overloading the disk prosthesis in flexion and complete unloading of the prosthesis in extension with the risk of dislocation.