Polyaxial Bone Anchor Assembly for Flexible Rod Seating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bone anchor assemblies are challenging to select, manufacture, and use across various spinal surgical procedures due to their variety and complexity, leading to usability issues during implantation and coupling with instrumentation.
Innovation Solution
A single bone anchor assembly with a receiver member featuring a U-shaped seat, polyaxial seating, and multiple engagement features, including grooves, recesses, and a drag ring, allowing for improved implantation, coupling, and flexibility in receiving spinal fixation elements of varying sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple different bone anchor assemblies are used for different spinal procedures, then procedure-specific optimization is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies universality by designing a single bone anchor assembly with a polyaxial receiver member that can accommodate multiple rod diameters and configurations through adjustable arms and seats, eliminating the need for multiple procedure-specific anchor designs while maintaining optimization for different spinal procedures
2Adaptability or versatility
If multiple different bone anchor assemblies are used for different spinal procedures, then procedure-specific optimization is achieved, but surgical time and setup complexity increase
Solution Approach 1:
The polyaxial receiver member with adjustable arms and seats allows a single bone anchor assembly to be used across multiple spinal procedures, eliminating the need to exchange different anchor assemblies during surgery and reducing setup time while maintaining procedure-specific optimization
3Strength
If a rod is forced into a receiver member seat, then fixation is achieved, but risk of seat fracture increases
Solution Approach 1:
The patent applies preliminary action by providing a countersink hole in the receiver member seat that receives a countersink bit, creating a recess before rod insertion. This pre-formed recess accommodates the rod tip without forcing, reducing stress concentration and fracture risk while maintaining strong fixation
Solution Approach 2:
The patent changes the geometric parameters of the receiver member seat by creating a countersink hole with specific dimensions and depth, modifying the seat's structure to accommodate rod insertion forces and reduce stress concentration, thereby preventing seat fracture while maintaining fixation strength
4Strength
If the shank is implanted at an angle, then bone purchase is improved, but accurate positioning of the receiver member becomes difficult
Solution Approach 1:
The patent applies preliminary action by providing a guide hole in the shank that receives a guide wire before implantation. This pre-formed guide hole allows accurate positioning of the receiver member relative to the shank angle, ensuring precise alignment while maintaining the angled bone purchase configuration
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
Bone anchor assemblies are disclosed herein that provide for a single bone anchor assembly that can be utilized across a range of spinal surgical procedures, reduce manufacturing burden and cost, and provide for greater flexibility during a surgical procedure. The bone anchor assemblies disclosed herein include an implantable shank and a receiver member having two spaced apart arms which form a U-shaped seat to receive a rod, among other components. The bone anchor assemblies disclosed herein also provide a number of features to enhance capability and usability. Examples include features to facilitate better implantation of the shank, better coupling of instrumentation to the anchor, better performance in reducing a spinal fixation element, such as a rod, into the receiver member seat, and others.