Vertebral body tethering (VBT) represents a significant evolution in the surgical management of adolescent idiopathic scoliosis, offering a motion-preserving alternative to the more traditional arthrodesis procedures. This minimally invasive technique aims to correct spinal curvature while allowing the spine to retain its natural flexibility. By placing screws into the vertebral bodies and connecting them with a strong, flexible tether, the procedure leverages the patient's own growth to gradually guide the spine into a more aligned position. Unlike fusion, which eliminates motion in the fused segment, VBT seeks to preserve function and potentially reduce the long-term risks associated with spinal rigidity.
Understanding the Mechanism of Vertebral Body Tethering
The fundamental principle behind VBT is selective growth modulation. In cases of scoliosis, one side of the spine grows faster than the other, resulting in a progressive curve. The tether is placed on the convex side of the curve, typically spanning multiple vertebrae. As the patient grows, particularly during adolescence, the tension on the tether slows down growth on the convex side, while the unrestricted growth on the concave side continues. Over time, this differential growth allows the spine to gradually straighten and correct the deformity. This biological correction is the key distinction between VBT and purely mechanical corrective devices.
Ideal Candidates and Patient Selection
Not all patients with scoliosis are suitable candidates for vertebral body tethering, and strict selection criteria are essential for optimal outcomes. The procedure is generally indicated for patients with moderate, flexible curves caused by idiopathic scoliosis. Key factors include a patient's skeletal maturity, often assessed using the Risser sign or tricortical iliac apophyseal fusion, with significant remaining growth potential being a primary requirement. Additionally, the location and magnitude of the curve play a crucial role, as VBT is most effective for thoracic and thoracolumbar curves within a specific range. A thorough evaluation by a specialized spinal deformity surgeon is necessary to determine if VBT is the appropriate course of action.
Surgical Technique and Procedure
The VBT procedure is performed through a small, lateral incision in the chest wall, often referred to as a mini-open or video-assisted approach, which aims to minimize muscle disruption compared to traditional open surgeries. After exposing the vertebral bodies, the surgeon places screws into the anterior aspect of the vertebrae along the convex side of the curve. These screws are then connected by a polyethylene tether, which is tightened to the appropriate tension. The entire process is guided by real-time fluoroscopic imaging to ensure precise screw placement and tensioning. The goal is to achieve a correction of 50% to 60% of the original curve while preserving the spine's natural biomechanics.
Benefits and Potential Advantages
For suitable patients, the benefits of vertebral body tethering can be substantial, particularly when compared to spinal fusion. Because the procedure preserves motion in the treated segments, patients often maintain greater core strength and spinal flexibility. This preservation of motion is theorized to reduce the risk of adjacent segment disease, a condition where stress on unfused levels leads to future pain and degeneration. Furthermore, the minimally invasive nature of VBT typically results in less blood loss, reduced postoperative pain, a shorter hospital stay, and a quicker return to normal activities and sports. The aesthetic outcome is also highly favorable, as the incision is small and located in a cosmetically sensitive area, leading to a more discreet scar.
Risks and Considerations
More perspective on Vertebral body tethering surgery can make the topic easier to follow by connecting earlier points with a few simple takeaways.
