Non-fusion Surgeries of Lumbar Spine
If spine pain becomes so severe that it disrupts daily life or is accompanied by swelling, tenderness, or redness, it’s important to seek medical attention.
At Complete Orthopedics, our expert spine specialists are adept at treating spine pain through both surgical and non-surgical means. We examine symptoms, diagnose the condition, and recommend suitable treatments, including surgery if necessary.
Serving New York City and Long Island, we partner with six hospitals to offer cutting-edge spine surgery and comprehensive orthopedic care. You can schedule a consultation with our orthopedic surgeons online or by phone.
Learn about the common causes of spine pain and the treatment options available, including when surgery might be the best choice.
Introduction to Low Back Pain and Spinal Treatments
Low back pain is a prevalent issue, affecting 70-85% of individuals in developed nations at some point in their lives. This condition can significantly impair daily functioning and quality of life. When conservative therapies such as physical therapy, medications, and lifestyle modifications fail to alleviate symptoms, more invasive treatments are considered. Among these, spinal fusion is a common surgical option. However, while effective in reducing pain, spinal fusion can accelerate degeneration in adjacent spinal segments, leading to further complications.
Nonfusion Treatments and Dynamic Spine Stabilization Devices
In response to the limitations of spinal fusion, nonfusion methods have been developed. These techniques aim to decrease mobility in specific spinal segments without completely eliminating it, thus preventing degeneration in adjacent levels. Dynamic spine stabilization devices are at the forefront of these nonfusion treatments. They can be categorized into anterior and posterior implants.
The Dynesys device is a well-known posterior option. It primarily limits motion during flexion rather than extension. Another device, the Elaspine, is designed to achieve consistent load distribution, offering a different approach to motion preservation.
Elaspine Device: Study and Findings
A recent study explored the Elaspine device’s impact on the range of motion (RoM) and compared it to other nonfusion devices. The study also assessed the strength of Elaspine’s pedicle screws in terms of anchorage, benchmarking them against other designs in existing literature. The results indicated that the Elaspine device significantly reduced the RoM in flexion, extension, and lateral bending compared to intact segments. However, its effect on restricting motion in axial rotation was similar to other nonfusion devices evaluated in prior studies.
Goals and Challenges of Motion Preservation Techniques
The primary objective of motion preservation techniques is to balance segmental motion with the protection of structural integrity. These techniques serve as a middle ground between segmental reconstruction and rigid fusions. However, biomechanical studies have revealed limitations, particularly in restricting axial rotation. Clinically, these techniques are most effective in the early stages of degeneration without significant instability. The challenge lies in matching the appropriate level of motion restriction to an individual’s specific segmental instability.
Pedicle Screw Performance and Challenges
One significant issue reported with motion preservation systems is the increased incidence of pedicle screw loosening and failure. This may result from altered screw loading observed in experimental and Finite Element studies. Pull-out tests have shown that the pedicle screws in the Elaspine device perform comparably to those reported in the literature, indicating good resistance to pull-out forces. This is a crucial factor in maintaining the device’s stability and effectiveness over time.
Comparing Nonfusion Devices
Comparing the effects of various nonfusion devices on RoM post-surgery is complex due to differences in surgical techniques and the extent of decompressions or defects created in vitro studies. The required stabilizing capability of a device depends on the RoM increase caused by these interventions.
Outcomes of Nonfusion Devices: Elaspine vs. Others
Following surgical destabilization, the Elaspine device showed similar outcomes to the StabilimaxNZ and a hinged pedicle screw system in terms of lateral bending and flexion/extension. However, none of these devices achieved a reduction in RoM in axial rotation to levels lower than the intact state.
The Dynesys device exhibited a RoM between 20% and 40% of the intact specimen in lateral bending and flexion/extension. In axial rotation, its RoM ranged from 90% to 101% of the intact state. One study reported a reduced motion restricting effect for the Dynesys device, attributed to a larger increase in RoM caused by the simulated surgical intervention. To accurately assess a device’s effect post-surgery, it is essential to consider the disparity between the instability induced by the surgery and the resulting RoM after device instrumentation.
Factors Influencing Device Performance
Several factors can influence the performance of these devices, including specimen age, bone mineral density, pedicle geometry, and cortical thread purchase. No correlation was observed between bone mineral density and maximum pull-out force. At lower loads, the initial fixation of the screw in the trabecular structure of the vertebra and pedicle enhances stiffness. However, as the loads increase, the fracturing of trabeculae causes a decline in pull-out stiffness.
Clinical Implications and Future Directions
The Elaspine motion preservation device, as studied, falls within the performance range of other devices examined in literature and clinical trials. Compared to the widely used Dynesys device, Elaspine offers greater flexibility and more natural motion in lateral bending and flexion/extension, though it is less effective in limiting motion in axial rotation. The pull-out force of Elaspine pedicle screws is comparable to other reported screw designs. Determining the optimal clinical application of these devices remains an area of active research and debate.
Spinal Fusion and Nonfusion Technologies
Spinal fusion aims to eliminate motion at a painful vertebral segment, providing pain relief by preventing movement. However, it alters the biomechanics of the spine, often leading to accelerated degeneration of adjacent segments. This process, known as adjacent segment disease (ASD), is a significant drawback of spinal fusion.
Nonfusion technologies, such as dynamic stabilization devices, aim to address the limitations of spinal fusion. These devices allow controlled motion in the affected segment, reducing the stress on adjacent segments. By preserving some degree of motion, these technologies aim to maintain the spine’s natural biomechanics and delay or prevent ASD.
Detailed Analysis of Study Results
In the detailed study of the Elaspine device, researchers investigated its biomechanical properties and compared its performance to other established devices. The Elaspine device was tested for its ability to reduce RoM in different planes of motion: flexion, extension, lateral bending, and axial rotation. The study included both intact spinal segments and segments with surgically induced structural defects in the intervertebral disc.
Flexion and Extension
The Elaspine device significantly reduced RoM in flexion and extension compared to intact segments. This reduction in motion is crucial for patients with instability or degenerative changes in the spine, as it helps to stabilize the affected segment while allowing some degree of motion. The device’s performance in flexion and extension was comparable to other nonfusion devices, such as the Dynesys and StabilimaxNZ.
Lateral Bending
In lateral bending, the Elaspine device also showed a significant reduction in RoM compared to intact segments. This reduction helps in stabilizing the spine and preventing excessive side-to-side movement, which can be painful and damaging in degenerative conditions.
Axial Rotation
The study found that the Elaspine device’s ability to restrict motion in axial rotation was similar to other nonfusion devices. However, axial rotation remains a challenging aspect for many motion preservation technologies. The ability to control rotational forces without completely eliminating motion is crucial for maintaining spinal function and preventing further degeneration.
Pedicle Screw Anchorage
The strength and stability of pedicle screws are vital for the success of any spinal stabilization device. In the Elaspine device, the pedicle screws demonstrated good resistance to pull-out forces, comparable to other designs reported in the literature. This finding is significant as it indicates the device’s reliability in maintaining stability over time, which is essential for patient outcomes.
Clinical Applications and Limitations
The clinical application of motion preservation devices should be limited to early stages of degeneration without significant instability. These devices are not suitable for all patients, and careful selection is crucial for achieving optimal outcomes. The challenge lies in matching the appropriate level of motion restriction to the individual’s specific segmental instability.
Future Research Directions
Future research should focus on improving the design and performance of motion preservation devices. This includes developing technologies that better control axial rotation and enhance the stability and longevity of pedicle screws. Additionally, long-term clinical studies are needed to assess the outcomes and potential complications of these devices in a broader patient population.
Conclusion
Low back pain is a significant health issue affecting a large portion of the population. Spinal fusion, while effective, has its limitations, leading to the development of nonfusion technologies like dynamic spine stabilization devices. The Elaspine device represents a promising option in this field, offering significant reductions in RoM in flexion, extension, and lateral bending, with comparable performance in axial rotation to other nonfusion devices.
Do you have more questions?
How does spinal fusion surgery work?
Spinal fusion involves joining two or more vertebrae together using bone grafts and possibly metal rods and screws. This eliminates movement between the fused vertebrae, reducing pain caused by motion.
What are the primary causes of low back pain?
Low back pain can be caused by a variety of factors including muscle strain, ligament sprain, herniated discs, spinal stenosis, degenerative disc disease, and osteoarthritis.
What are the risks associated with spinal fusion surgery?
Risks include infection, blood clots, nerve damage, non-union of the bones, and adjacent segment disease, where nearby vertebral segments degenerate more quickly.
How do dynamic spine stabilization devices differ from spinal fusion?
Unlike spinal fusion, which eliminates motion at the fused segment, dynamic stabilization devices allow for controlled motion, aiming to reduce the stress on adjacent segments and prevent further degeneration.
What are nonfusion treatments for spinal conditions?
Nonfusion treatments include dynamic spine stabilization devices, which reduce motion at specific segments without eliminating it, thus preserving some spinal mobility.
What is the Dynesys device, and how does it function?
The Dynesys device is a posterior dynamic stabilization system that uses flexible materials to limit motion more in flexion than in extension, providing stability while allowing some movement.
What is the Elaspine device, and how is it different from Dynesys?
The Elaspine device is another type of posterior dynamic stabilization device that focuses on achieving consistent load distribution. It offers greater flexibility and more natural motion in lateral bending and flexion/extension compared to Dynesys.
What limitations does the Elaspine device have?
The Elaspine device is less effective in limiting axial rotation compared to other nonfusion devices, which can be a limitation in certain clinical scenarios.
What are the benefits of using the Elaspine device?
The Elaspine device significantly reduces the range of motion in flexion, extension, and lateral bending, which helps stabilize the spine while maintaining some degree of mobility.
How does the strength of Elaspine’s pedicle screws compare to other designs?
The pedicle screws used in the Elaspine device perform comparably to other designs in terms of resistance to pull-out forces, indicating good anchorage and stability.
What are the potential complications of using dynamic stabilization devices?
Potential complications include screw loosening, device failure, infection, and continued pain if the device does not adequately stabilize the affected segment.
What are the clinical indications for using dynamic stabilization devices?
These devices are typically used in patients with early stages of spinal degeneration who do not have significant instability and are not suitable candidates for spinal fusion.
How does bone mineral density affect the performance of pedicle screws?
Bone mineral density can influence the initial fixation and long-term stability of pedicle screws. Higher density generally provides better anchorage, but no direct correlation with maximum pull-out force has been observed.
Can dynamic stabilization devices be used in patients with severe spinal instability?
These devices are generally not recommended for patients with severe instability, as they are designed for cases with mild to moderate degeneration and limited instability.
Why is axial rotation a challenging aspect for motion preservation devices?
Axial rotation involves complex, multi-directional forces that are harder to control without completely eliminating motion. Achieving the right balance of restriction and flexibility in rotation is technically challenging.
What are the long-term outcomes of using dynamic stabilization devices?
Long-term outcomes can vary. Some studies show positive results in maintaining mobility and reducing pain, but more research is needed to fully understand their long-term effectiveness and potential complications.
What are adjacent segment disease (ASD) and its significance?
ASD refers to the accelerated degeneration of spinal segments adjacent to a fused segment. It is a significant concern with spinal fusion, as it can lead to further pain and the need for additional surgeries.
How do surgeons decide between using spinal fusion and dynamic stabilization?
The decision is based on several factors, including the extent of degeneration, patient age, activity level, bone quality, and the specific spinal segments involved. Each case is evaluated individually.
How do dynamic stabilization devices aim to prevent ASD?
By preserving some degree of motion at the treated segment, these devices aim to reduce the stress on adjacent segments, potentially slowing or preventing the onset of ASD.
Are there any alternatives to dynamic stabilization and spinal fusion?
Other alternatives include disc replacement, minimally invasive surgeries, and advanced physical therapy techniques. Each has its own indications and potential benefits.
What advancements are being made in the design of dynamic stabilization devices?
Research is ongoing to improve the materials, biomechanics, and anchorage of these devices. Future designs may offer better control of axial rotation and enhanced long-term stability.
How do dynamic stabilization devices affect rehabilitation and recovery?
These devices can potentially lead to a faster recovery compared to spinal fusion, as they aim to maintain some spinal mobility. However, the rehabilitation process will still include physical therapy and gradual return to activities.
How do surgeons monitor the effectiveness of dynamic stabilization devices post-surgery?
Surgeons use a combination of clinical evaluations, imaging studies (such as X-rays and MRIs), and patient-reported outcomes to monitor the effectiveness and stability of the device over time.
What should patients expect during the recovery period after dynamic stabilization surgery?
Recovery typically involves a period of rest, followed by a structured physical therapy program to strengthen the back and improve mobility. Most patients can return to normal activities within a few months.
What are the future research directions for nonfusion spinal treatments?
Future research will likely focus on optimizing device designs, understanding long-term outcomes, exploring patient-specific factors that influence success, and developing new materials that enhance device performance and patient comfort.
I am Vedant Vaksha, Fellowship trained Spine, Sports and Arthroscopic Surgeon at Complete Orthopedics. I take care of patients with ailments of the neck, back, shoulder, knee, elbow and ankle. I personally approve this content and have written most of it myself.
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