Flexible Spinal Element with Helical Slots for Dynamic Stabilization
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Solution Overview
Problem
Current spinal fusion methods impose unnatural stresses on adjacent vertebrae, limit flexional and torsional movements, and are prone to in vivo failure due to the use of rigid constructs, while dynamic stabilization devices face challenges in replicating natural spinal motion and maintaining stability.
Innovation Solution
A flexible spinal element with longitudinally, laterally, and torsionally flexible components featuring helical slots cut at varying angles and widths, allowing for controlled flexibility and movement, and potentially filled with elastomeric materials to enhance durability and prevent tissue growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If rigid fixation devices are used for spinal fusion, then stabilization is improved, but flexibility and natural motion are lost
Solution Approach 1:
The rod is divided into multiple segments along its length, with each segment having distinct slot configurations. The rod comprises a first segment with first slots and a second segment with second slots, allowing different flexibility characteristics in different regions while maintaining overall structural integrity and stabilization function.
Solution Approach 2:
Different portions of the rod have different slot patterns and flexibility characteristics tailored to specific spinal regions. The first segment has different slot configurations than the second segment, enabling localized adaptation to varying biomechanical requirements along the spinal column while maintaining overall stability.
2Stability of the object's composition
If rigid constructs are used for spinal fusion, then stabilization is improved, but in vivo failure risk increases due to unnatural stresses
Solution Approach 1:
The rod transitions from a completely rigid structure to a dynamically adaptable structure with controlled flexibility. The slot configurations allow the rod to dynamically adjust to physiological loads and motions, reducing stress concentration and improving implant survival while maintaining stabilization function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The flexible spinal element provides natural movement and stability by allowing for bending, twisting, and tensile, compressive, and torsional flexibility, reducing the risk of implant failure and improving healing outcomes by mimicking the spine's natural biomechanics.
Implementation Method 1
A flexible rod component for dynamically stabilizing a portion of the spine comprises a tubular member with a longitudinal axis and a helical slot extending around and along a flexible segment of the tubular member. The slots have a width of between 2.5% and 10% of the diameter of said spinal element, an angle from about 5 degrees to about 20 degrees, a ratio of amplitude to pitch in the range of from greater than 0.1 to about 0.8 and about 4-6 cycles per diameter length.
Implementation Method 2
The slots have a width of between 2.5% and 10% of the diameter of said spinal element... The flexible component can further have different degrees of flexibility along its length achieved by having the pitch of the helical slot vary along the length of the shaft.
Data Source
AI summary
An improved flexible component used for dynamic stabilization of spinal segments for the treatment of vertebrae deformities and injuries and for the replacement of a complete or segment of the body of a vertebra in the spine is described. The flexible component is comprised of a suitable implant material with a longitudinal bore the entire length and an appropriately formed slots that extend spirally around the flexible spinal element either continuously or segmentally. The flexible component can be encapsulated, fully or partially, in a suitable implant grade elastomeric resilient material. When used for a dynamic stabilization device, the element is attached to the vertebral bodies by pedicle screws know to those in the art.