Spinal Stabilization Rod with Taper Lock Screw
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Solution Overview
Problem
Current spinal fixation systems face challenges in providing a cost-effective, rigid screw and rod construct that maintains a low profile while ensuring sufficient strength, especially for large deformity corrections, and often require material incompatibility to prevent profile increase.
Innovation Solution
A spinal stabilization system utilizing a multi-planar taper lock screw and connecting rod with a dual layered housing and spherically configured screw head, allowing for secure locking and multi-planar rotational articulation, and a connecting rod with an elongate rounded section and rectangular head portion for enhanced rigidity without increasing the profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If larger diameter rods are used to improve strength for large deformity corrections, then the strength of the screw and rod construct is improved, but the profile of the construct increases
Solution Approach 1:
The patent employs a composite material strategy by combining titanium alloy (biocompatible, corrosion-resistant) for the rod with stainless steel (higher strength) for the screw assembly. This allows the weaker titanium rod to be used instead of larger stainless steel rods, reducing profile while maintaining overall construct strength through the superior mechanical properties of the stainless steel screw-rod interface
Solution Approach 2:
The invention applies different material qualities to different components: the rod maintains biocompatibility and flexibility with titanium alloy, while the screw assembly (head and locking mechanism) uses high-strength stainless steel. This localized application of material properties optimizes both strength where needed and profile where possible
2Strength
If larger diameter stainless steel rods are used to improve strength, then the strength is improved, but material incompatibility issues arise and cost increases
Solution Approach 1:
The patent resolves material incompatibility and cost issues by strategically combining two materials: titanium alloy for the rod (providing biocompatibility and corrosion resistance) and stainless steel for the screw assembly (providing high strength). This composite approach avoids the need for entirely stainless steel construction while maintaining structural integrity and reducing overall cost
Solution Approach 2:
Different material qualities are assigned to different components based on their functional requirements: titanium alloy where biocompatibility is paramount (rod), and stainless steel where mechanical strength is critical (screw head and locking mechanism)
3Stability of the object's composition
If larger rod constructs are used to provide rigid stabilization, then the rigidity is improved, but the surgical profile and implant size increase
Solution Approach 1:
The patent achieves rigid stabilization with a smaller profile by using composite materials: the titanium alloy rod provides appropriate flexibility and biocompatibility, while the stainless steel screw assembly provides the necessary rigidity and locking strength. The combination creates a rigid construct without requiring a larger rod diameter
Solution Approach 2:
The spherical head configuration of the bone anchor allows for multi-planar rotation and articulation within a compact geometry. This spherical design enables rigid multi-directional stabilization while maintaining a small overall profile, as the sphere efficiently distributes stresses in all directions without requiring additional space
Data Source
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AI summary
A spinal stabilization system includes a connecting rod, a rod bending device, and a plurality of bone screws. The connecting rod includes an elongate round portion, an elongate head portion and a neck portion connecting the elongate round portion with the elongate head portion. The rod bending device includes an elongate body defining an aperture configured and dimensioned to receive the connecting rod therethrough in a single orientation. The bone screws include a housing portion and a screw shaft distally extending from the housing portion. The housing portion includes an inner housing and an outer housing slidably surrounding at least a portion of the inner housing. The inner housing defines a slot configured and dimensioned to releasably secure the elongate round portion of the connecting rod therein. The outer housing is movable relative to the inner housing between an unlock state and a locked state.