Spinal Stabilization Screw Assembly for Osteoporotic Bone Fixation
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Solution Overview
Problem
Existing spinal stabilization devices face issues such as screws loosening and backing out of vertebrae, especially in osteoporotic bone, requiring revision surgeries and compromising structural stability, and difficulty in aligning screws with rods during spinal procedures.
Innovation Solution
The development of spinal stabilization devices featuring a compressible head, longitudinally-curved shank with friction members, and pivotable fastener members that enhance stability and allow for adjustable screw depth without further insertion or removal, utilizing materials like titanium and PEEK, and employing minimally-invasive techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional screws are used to fasten stabilization devices to vertebrae, then the devices can be secured to bone, but the screws may loosen and back out especially in osteoporotic bone
Solution Approach 1:
The stabilization device is divided into multiple functional components: a bone fastener (screw) for anchoring to vertebrae, a coupling element (tulip element) for connecting to the rod, and clamp/wedge elements for securing the fastener in the coupling element. This segmentation allows each component to be optimized for its specific function, improving overall reliability while maintaining structural stability.
Solution Approach 2:
The device incorporates dynamic elements such as the compressible head that can deform under load to enhance grip in osteoporotic bone, and the pivotable fastener members that allow for adjustment during installation. These dynamic features enable the device to adapt to varying bone densities and installation conditions, preventing loosening while maintaining structural integrity.
2Reliability
If larger screws are used to prevent loosening in osteoporotic bone, then stability may be improved, but the complexity of the procedure increases and revision surgeries may be required
Solution Approach 1:
The device utilizes materials with specific mechanical properties, such as titanium and PEEK, which offer optimal strength-to-density ratios. The compressible head design changes the effective engagement parameters by allowing controlled deformation to match bone density, achieving reliable fixation without requiring larger screw dimensions or more complex procedures.
Solution Approach 2:
The stabilization device employs composite material construction, combining titanium for the bone fastener (providing strength and osseointegration) with PEEK for the rod and coupling elements (providing flexibility and radiolucency). This composite approach achieves high reliability with optimized device geometry rather than increased size, reducing procedural complexity.
3Ease of operation
If traditional alignment methods are used during spinal procedures, then screws can be inserted into vertebrae, but aligning screws with rods presents difficulty
Solution Approach 1:
The device design incorporates preliminary alignment features such as the longitudinally-curved shank with friction members that guide the screw insertion path. The coupling element is pre-configured to receive the bone fastener at the correct orientation, ensuring automatic alignment with the rod before final securing, thereby simplifying the surgical procedure while maintaining high alignment precision.
Solution Approach 2:
The coupling element (tulip element) serves as an intermediary component between the bone fastener and the rod. It provides a standardized interface that automatically aligns the screw with the rod axis, eliminating the need for complex manual alignment procedures while ensuring precise positioning for optimal structural integrity.
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
These devices increase the stability of the bone-screw interface, reduce the likelihood of screw loosening, and enable precise alignment with rods, potentially eliminating the need for larger screws and minimizing revision surgeries.
Implementation Method 1
a compressible head
Implementation Method 2
an elongate, longitudinally-curved shank extending therefrom and comprising at least one friction member
Data Source
AI summary
A spinal stabilization device having an anchor and a bone fixation members, such as bone screws, for use in orthopedic stabilization assemblies.