VERTEBRAL BODY TETHERING

Questions and Answers

Vertebral Body Tethering

Vertebral Body Tethering (VBT) is an innovative surgical technique designed to treat scoliosis in children and adolescents who are still growing. Unlike traditional spinal fusion, VBT aims to correct spinal curvature while preserving the spine’s natural flexibility and allowing for continued growth.

Understanding Scoliosis and the Need for VBT

Scoliosis is a lateral curvature of the spine that typically manifests during the growth spurts of childhood or adolescence. While doctors manage mild cases with observation or bracing, progressive curves can lead to significant deformity, discomfort, and potential cardiopulmonary complications. Traditional treatment often involves spinal fusion, which straightens the spine but results in a loss of segmental motion and potential long-term complications. VBT offers a motion-preserving alternative for select patients.

Vertebral Body Tethering (VBT) is a surgical treatment for scoliosis that has received approval from the U.S. Food and Drug Administration (FDA) under a Humanitarian Device Exemption (HDE). This approval is specifically for “The Tether™ – Vertebral Body Tethering System,” intended for skeletally immature patients requiring surgical intervention to correct progressive idiopathic scoliosis with a major Cobb angle of 30 to 65 degrees. Candidates for this procedure are typically those who have not responded to bracing or cannot tolerate it.

It’s important to note that the HDE pathway is designed for devices treating conditions affecting fewer than 8,000 individuals annually in the United States. While it allows for the marketing of the device, it does not require the same level of evidence as a full premarket approval (PMA). Therefore, VBT is considered an approved treatment option under specific conditions but is not broadly approved for all scoliosis cases. Patients and families should engage in thorough discussions with their healthcare providers to understand the potential benefits and risks associated with VBT and to determine if it’s the most appropriate treatment option for their specific situation.

For more detailed information, read the FDA’s official press announcement that provides additional insights into the approval and intended use of The Tether™ – Vertebral Body Tethering System.

Additionally, the Scoliosis Research Society offers a comprehensive overview of vertebral body tethering, including patient selection criteria and considerations.

The VBT Procedure

VBT is performed through a minimally invasive thoracoscopic approach, involving small incisions made between the ribs. The surgeon attaches screws to the vertebral bodies along the convex (outer) side of the spinal curve. A flexible polyethylene tether is then secured to these screws and tensioned to partially correct the curvature. As the child grows, the tether modulates growth on the convex side, allowing the concave (inner) side to catch up, thereby progressively straightening the spine over time.

Advantages of VBT

• Preservation of Spinal Mobility: Unlike spinal fusion, VBT maintains the natural movement of the spine, which is particularly beneficial for active children.
• Continued Spinal Growth: By modulating growth, VBT allows for the potential of further spinal development and correction as the child matures.
• Minimally Invasive Approach: The thoracoscopic technique results in smaller scars and may reduce recovery time compared to open surgical methods.

Ideal Candidates for VBT

VBT is most effective in patients who:

• Are still growing, typically indicated by a Sanders Skeletal Maturity Score of 3 to 5.
• Have a spinal curvature between 40 and 65 degrees.
• Have not responded to bracing or are unsuitable candidates for bracing.

It’s essential for patients to undergo a thorough evaluation by a specialized orthopedic surgeon to determine suitability for VBT.

Postoperative Care and Recovery

Recovery from VBT involves a hospital stay of several days, during which pain management and respiratory exercises are emphasized. Doctors recommend physical therapy to aid in the return to normal activities. Most patients can resume regular, non-contact activities within a few weeks, with a gradual return to full activities, including sports, over several months.

Considerations and Potential Risks

While VBT presents numerous advantages, it’s important to consider potential risks, including:

• Overcorrection or Undercorrection: The dynamic nature of growth modulation can sometimes lead to overcorrection or insufficient correction of the spinal curve.
• Device-Related Complications: There is a possibility of tether breakage or screw displacement, which may necessitate additional interventions.
• Limited Long-Term Data: As a relatively new procedure, long-term outcomes are still being studied, and the longevity of the correction is not fully established.

Additional Risks

Vertebral Body Tethering represents a promising advancement in the treatment of scoliosis for growing children, offering the potential for curve correction while maintaining spinal flexibility. However, careful patient selection and thorough discussion of the benefits and risks with a specialized orthopedic surgeon are crucial to achieving optimal outcomes.

Vertebral Body Tethering (VBT) is a relatively new surgical approach for treating scoliosis, particularly in skeletally immature patients. Recent studies have provided insights into its effectiveness and associated outcomes.

Clinical Success Rates

• A systematic review involving 26 studies and 1,045 patients reported an overall clinical success rate of approximately 73%, with a pooled unplanned reoperation rate of about 8.7%.
• Another study with a minimum three-year follow-up found a clinical success rate of 73%, indicating that VBT can help.

Tethering (VBT) is a promising alternative to traditional spinal fusion for treating scoliosis, particularly in growing children and adolescents. While early results have been encouraging, indicating effective curve correction and maintenance of spinal flexibility, long-term data is still emerging, and some studies have reported complications such as tether breakage and curve progression. Tether breakage is a notable complication associated with Vertebral Body Tethering (VBT), a surgical treatment for scoliosis. Understanding its incidence, detection methods, implications, and management strategies is crucial for patients considering or undergoing this procedure.

For instance, a study from Children’s Hospital Los Angeles found that 50% of patients experienced curve progression after tether breakage. Given these considerations, it’s crucial for patients and families to consult with experienced orthopedic surgeons to thoroughly discuss the potential benefits and risks of VBT, ensuring an informed decision tailored to the patient’s specific condition and growth potential.

Complication Studies

Studies indicate that tether breakage is relatively common post-VBT:

• An article by PubMed reported that approximately 36% of patients experience tether breakage within three years postoperatively, with an estimated 50% incidence by 36 months.
• An article by the Pediatric Spine Foundation found that breakages typically occur between 1.5 to 3 years after surgery.

Factors Contributing to Tether Breakage

Several factors may influence the likelihood of tether breakage:

• Material Fatigue: The tether, made of braided polypropylene, is subject to fatigue over time due to constant motion, potentially leading to failure.
• Skeletal Maturity: Patients with significant growth remaining may exert more stress on the tether, increasing the risk of breakage.

Complication Detection Methods

Detecting tether breakage involves radiographic assessments:

• Inter-Screw Angle Increase: An increase of more than 5 degrees between adjacent screws may suggest tether breakage.
• Inter-Screw Index: A novel method measuring the percentage increase in distance between screws; a 13% or greater increase may indicate breakage.

The consequences of Tether Breakage

The implications of tether breakage can vary:

• Curve Progression: Approximately 50% of patients may experience curve progression of at least 5 degrees within two years following a break, with 25% seeing a worsening of more than 10 degrees.
• Reoperation Rates: About 15% of patients with tether breakage may require revision surgery, including the possibility of conversion to spinal fusion.

Addressing tether breakage involves:

• Monitoring: Regular follow-up with radiographic evaluations to detect early signs of breakage and assess curve progression.
• Surgical Intervention: In cases of significant curve progression or symptomatic concerns, doctors may consider revision surgery, including possible replacement of the tether or conversion to spinal fusion.

Conclusion

While VBT offers the advantage of preserving spinal mobility, the potential for tether breakage necessitates thorough preoperative counseling and diligent postoperative monitoring. Patients and families should engage in detailed discussions with their orthopedic surgeons to fully understand the risks, benefits, and long-term implications of VBT, ensuring informed decision-making tailored to the patient’s specific circumstances.

Why Choose the Southwest Scoliosis and Spine Institute

Patients should choose the doctors from the Southwest Scoliosis and Spine Institute for scoliosis surgery.  Clearly, the primary reason is due to their unparalleled expertise and experience. For example, the institute is renowned for its board-certified, fellowship-trained surgeons.  Significantly, these surgeons have treated over 100,000 patients and performed more than 16,000 successful scoliosis surgeries, including complex and revision cases. Finally, the team’s commitment to personalized care ensures that each patient receives a tailored treatment plan. Additionally, the institute’s focus on cutting-edge research and advanced surgical techniques provides patients with the best possible outcomes, enhancing both function and quality of life.