Modular Bone Screw Assembly via Spring-Locked Pressure Element
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Solution Overview
Problem
Existing polyaxial bone screws are typically delivered pre-assembled, limiting flexibility and requiring sophisticated tools for assembly, which complicates handling and increases costs, inventory, and restricts the surgeon's choice of implants.
Innovation Solution
A modular bone anchoring device with a simplified design, allowing assembly by hand using a few parts and a user-friendly assembly tool, enabling combination of various anchoring elements with suitable receivers, and an insertion tool for safe handling during surgery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyaxial bone screws are delivered pre-assembled, then the structural integrity and reliability are improved, but the flexibility and surgeon's choice are limited, and inventory costs increase
Solution Approach 1:
The bone anchoring device is divided into separate components (anchoring element, receiving part, pressure element) that can be assembled intraoperatively. This segmentation allows surgeons to select and combine different components based on specific surgical needs, thereby improving versatility while maintaining structural integrity through proper design of each segment
Solution Approach 2:
The device transitions from a static pre-assembled state to a dynamic assembly process. The pressure element is designed to be insertable and removable, allowing the system to adapt from an open assembly state to a locked assembled state, providing both flexibility during surgery and stability during use
2Manufacturing precision
If sophisticated tools are used for assembly, then the manufacturing precision and reliability are improved, but the device complexity and handling difficulty increase
Solution Approach 1:
The pressure element incorporates self-aligning features and simple engagement mechanisms that allow assembly without sophisticated tools. The design includes features like tapered surfaces and simple geometric constraints that guide proper assembly, enabling surgeons to assemble the device manually while maintaining adequate precision
Solution Approach 2:
The device is designed for single-use with simple assembly features that eliminate the need for expensive, complex assembly tools. The simplicity of the assembly mechanism allows for disposable use while keeping the overall system cost-effective and easy to handle
3Reliability
If the pressure element is firmly held in position, then the stability and reliability are improved, but the ease of assembly and disassembly deteriorates
Solution Approach 1:
The pressure element employs a dynamic locking mechanism that transitions from an easily insertable state to a firmly secured state. During assembly, the pressure element can be freely inserted, but once in position, it locks firmly through geometric interlocking or friction-based retention, providing both ease of assembly and position stability
Solution Approach 2:
The pressure element acts as an intermediary component that mediates between the anchoring element and receiving part. It provides a simple engagement interface that allows easy insertion while creating a stable, firm connection through its interaction with the other components
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 easy assembly and handling of polyaxial bone screws by surgeons, reduces manufacturing costs, and provides a modular system for upgrading existing parts, offering a substantial choice of implants and reducing inventory while ensuring safe surgical procedures.
Implementation Method 1
The pressure element comprises a spring element that engages a portion of the receiving part so that it can be held in a position that allows pivoting of the anchoring element
Data Source
AI summary
A bone anchoring device includes an anchoring element having a shaft for anchoring in the bone and a head, a receiving part formed in one piece, and a pressure element formed in one piece. The receiving part has a seat for receiving the head and an outer channel for receiving a rod to be connected to the anchoring element, which is pivotable with respect to the receiving part and can be fixed at an angle by exerting pressure via the pressure element onto the head. The pressure element is movable in the receiving part and includes an inner channel for receiving the rod and a spring element that engages a portion of the receiving part via a detent connection so that the pressure element can be held in a position that allows pivoting of the anchoring element. The spring element is formed by at least a first portion of one of two side walls forming the inner channel, the first portion being spaced apart from a second portion of the one side wall by a slot. At least a portion of the detent connection is located on the one side wall.