Polyaxial Bone Anchor Pressure Member for Rod-Activated Locking
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Solution Overview
Problem
Existing polyaxial bone anchoring devices require additional locking members for securing the bone anchoring element to a rod, which complicates surgical procedures and reduces flexibility during adjustments.
Innovation Solution
A polyaxial bone anchoring device with a deformable pressure member that uses a toggle lever mechanism, allowing the bone anchoring element to be locked or unlocked by inserting or removing a rod, eliminating the need for additional locking members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional locking members are used to secure the bone anchoring element to the rod, then the reliability of the connection is improved, but the device complexity and ease of operation deteriorate
Solution Approach 1:
The pressure member integrates multiple functions: it provides the locking action through its deformable portion, serves as the locking mechanism itself, and directly contacts both the head and rod. This merging of functions eliminates the need for separate locking members while maintaining connection reliability
Solution Approach 2:
The deformable portion of the pressure member automatically deforms under rod insertion to engage and lock the head in place without requiring additional locking members or complex assembly steps. The system locks itself through the mechanical interaction between the rod, deformable portion, and head
2Stability of the object's composition
If additional locking members are used to secure the bone anchoring element to the rod, then the connection stability is improved, but the ease of operation deteriorates
Solution Approach 1:
The pressure member with deformable portion automatically engages and locks the head when the rod is inserted, eliminating the need for surgeons to manually operate additional locking members. The system performs the locking action itself through the mechanical interaction, greatly simplifying the surgical procedure
Solution Approach 2:
The invention extracts and eliminates the additional locking members from the system, retaining only the essential pressure member with deformable portion that provides both locking and stabilization functions, thereby simplifying the operational steps required during surgery
3Reliability
If the deformable portion is designed to provide strong clamping force, then the connection reliability is improved, but the ease of manufacture deteriorates
Solution Approach 1:
The deformable portion is designed with specific material properties and geometric parameters that allow it to deform under controlled conditions during rod insertion while providing strong clamping force. By optimizing the thickness, material elasticity, and geometry of the deformable portion, the design achieves reliable locking without requiring complex manufacturing processes
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
Facilitates easier and more flexible handling during surgery by enabling angular adjustments of the bone anchoring element relative to the rod without additional locking members, improving surgical efficiency and versatility.
Implementation Method 1
The deformable portion functions similar to a toggle lever that transforms or adjusts from an angled configuration into a less angled or substantially straight configuration
Implementation Method 2
The deformable portion can be deformed from a first configuration into a second configuration. Due to the deformation, the pressure exerted by the pressure member onto the head increases
Implementation Method 3
the rod can be held in the channel by friction in a manner such that the position of the rod relative to the receiving part can be changed by applying a force that overcomes the friction force
Data Source
AI summary
A polyaxial bone anchoring device includes a bone anchoring element having a head, a receiving part having a channel for receiving a rod and an accommodation space for pivotably holding the head, and a pressure member having a pressure exerting surface and a deformable portion with a free end. The deformable portion is adjustable from a first configuration where a first part of the deformable portion is supported at a first axial position relative to the receiving part while a second part of the deformable portion protrudes further radially into the channel than parts of the deformable portion positioned axially above the second part, to a second configuration where the second part of the deformable portion is deformed radially outwardly and the pressure exerting surface is shifted lower axially to exert pressure on the head while the first part of the deformable portion remains supported at the first axial position.