Dynamic Spinal Stabilization Using Flexible Spring Elements
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Solution Overview
Problem
Rigid fixation systems used in spinal fusion procedures can compromise bone quality due to excessive stress, leading to issues like bone shearing, and existing dynamic stabilization systems do not adequately preserve spinal motion and function while reducing pain.
Innovation Solution
A dynamic stabilization system incorporating a bone fixation element, such as a bone screw, combined with a flexible element like a spring, which allows for extension, compression, and polyaxial movement of an elongated fixation element relative to the bone, thereby reducing stress on the bone and preserving spinal motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid fixation system is used to stabilize the spine, then spinal stability is improved, but bone quality deteriorates due to excessive stress causing bone shearing
Solution Approach 1:
The patent applies the dynamics principle by replacing the rigid fixation system with a dynamic stabilization system that incorporates flexible elements (springs) allowing controlled movement between the bone fixation element and the elongated fixation element. This dynamic construction enables the system to adapt to physiological spinal motion while maintaining stability, thereby reducing excessive stress on the bone and preserving bone quality.
Solution Approach 2:
The patent changes the mechanical parameter of the fixation system from rigid (fixed stiffness) to flexible (variable stiffness through spring elements). The spring constant and flexibility of the connection can be adjusted to allow appropriate motion while maintaining stabilization, thus reducing stress concentration on the bone and preventing bone shearing.
2Stability of the object's composition
If a rigid fixation system is used to eliminate pain, then spinal stabilization is improved, but normal spinal motion and function are lost
Solution Approach 1:
The dynamic stabilization system incorporates flexible connection elements that permit controlled movement between fixed points, allowing the spine to maintain its natural range of motion while still providing stabilization. This resolves the contradiction by enabling both spinal stability and preserved motion functionality simultaneously.
3Strength
If a dynamic stabilization system with flexible elements is used, then stress on bone is reduced and spinal motion is preserved, but device complexity increases
Solution Approach 1:
The patent employs spring elements as flexible connections between the bone fixation element and the elongated fixation element. These spring elements provide the necessary flexibility and motion capability while maintaining structural integrity, achieving bone protection and motion preservation without excessive complexity.
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 system effectively reduces stress on compromised bones, preserves normal spinal motion and function, and minimizes pain by allowing the elongated fixation element to move with respect to the bone fixation element, thus providing a more stable and comfortable solution for patients.
Implementation Method 1
The flexible element is preferably in the form of a spring
Implementation Method 2
The flexible element preferably permits extension and/or compression of the elongated fixation element
Implementation Method 3
The spring connects the bone fixation element to an elongated fixation element so that the elongated fixation element is permitted to polyaxially move with respect to the bone fixation element
Data Source
AI summary
A dynamic bone fixation element for securing an elongated fixation element such as, a longitudinal rod or bone plate, to a patient's bone, preferably a vertebra. The dynamic bone fixation element preferably includes a bone fixation element and a flexible element for connecting the bone fixation element to the elongated fixation element. The flexible element preferably permits the elongated fixation element to move with respect to the bone fixation element and hence with respect to the bone affixed thereto. The flexible element preferably permits extension and/or compression of the elongated fixation element with respect to the bone fixation element and polyaxially movement of the elongated fixation element with respect to the bone fixation element. The flexible element is preferably in the form of a spring or a spring-like flexible element.