In-situ Bone Anchor Assembly for Spinal Fixation
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Solution Overview
Problem
Current bone fixation systems for spinal disorders require complex assembly and limited visibility during surgical implantation, hindering the precision and accessibility needed for effective spinal stabilization.
Innovation Solution
A bone anchor assembly that allows in-situ assembly, where the bone anchor is secured to the vertebra before being connected to the body, enabling a 'click-on' mechanism with a bushing and locking cap, facilitating easier implantation and providing polyaxial rotation capabilities for improved stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the bone anchor assembly is designed as a separate modular system requiring pre-assembly, then the assembly complexity increases and surgical accessibility is reduced, but the manufacturing precision and reliability of the connection can be improved
Solution Approach 1:
The bone fixation system is divided into separate modular components: bone anchor, body, bushing, and locking cap. Each component can be manufactured independently with high precision, then assembled during surgery. The body includes a bore and rod-receiving channel that precisely receive the bone anchor and spinal rod respectively, ensuring accurate alignment while maintaining modular assembly.
Solution Approach 2:
The bone anchor is pre-assembled with the bushing and locking cap in a predetermined sequence before surgery. The bushing is inserted into the body bore, then the bone anchor is inserted through the bushing, and finally the locking cap is secured. This pre-assembly sequence ensures proper positioning and alignment of all components, reducing intraoperative complexity while maintaining connection precision.
2Ease of operation
If the bone anchor is secured to the vertebra before connection to the body, then surgical accessibility and visibility are improved, but the assembly time and operational complexity increase
Solution Approach 1:
The bushing is designed to be movable within the body bore, allowing it to be positioned in different locations during assembly. The bushing can be inserted into the body first, then the bone anchor is inserted through the bushing, and the entire assembly can be positioned and secured to the vertebra. This dynamic positioning capability enables the surgeon to achieve optimal exposure and access to the vertebral insertion site while maintaining proper assembly sequence.
3Stability of the object's composition
If the rod-receiving channel is positioned at the lower end of the body, then the structural stability and load transmission are improved, but the accessibility for rod insertion and alignment is reduced
Solution Approach 1:
The rod-receiving channel is positioned at the lower end of the body, while the bone anchor insertion path goes through the upper end of the body via the bushing. This spatial arrangement in different dimensions allows the rod to be inserted from one direction (through the lower opening) while the bone anchor is inserted from another direction (through the upper opening), improving accessibility for rod insertion without compromising the structural stability provided by the lower-positioned rod-receiving channel.
Data Source
AI summary
An anchor assembly for use in spinal fixation to interconnect a longitudinal spinal rod with a patient's vertebra. The anchor assembly preferably includes a bone anchor, a body with a rod-receiving channel, an insert member (preferably a bushing), and a locking cap. The anchor assembly enables in-situ assembly where the bone anchor may be secured to the patient's vertebra prior to being received within the body of the bone anchor assembly. Accordingly, the anchor assembly enables a surgeon to implant the bone anchor without the body to maximize visibility and access around the anchoring site. Once the bone anchor has been secured to the patient's vertebra, the body may be snapped onto the bone anchor and a spinal rod may be inserted into the rod-receiving channel.