Polyaxial Bone Screw Coupling with Self-Locking Pressure Member
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Solution Overview
Problem
Conventional polyaxial bone anchoring devices lack efficient mechanisms for provisional and final locking of bone anchoring elements without requiring additional instruments, leading to increased complexity and time in surgical procedures.
Innovation Solution
A coupling device with a receiving part and a pressure member that allows for provisional locking of the bone anchoring element without external instruments, utilizing a latching connection and flexible actuating portions for easy adjustment and release, and a final locking mechanism using a locking member for enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional polyaxial bone anchoring device is used, then the bone anchoring element can be coupled to a rod, but the locking mechanism requires additional instruments and increases surgical complexity
Solution Approach 1:
The pressure member is configured to engage the receiving part by a latching connection, enabling the device to lock itself without requiring additional external instruments. The actuating portion of the pressure member can be engaged directly by the rod or locking member, allowing the system to perform its own locking function
Solution Approach 2:
The pressure member and receiving part are integrated into a single coupling device structure, combining the locking mechanism and receiving function into one unified component. This integration eliminates the need for separate locking instruments and reduces overall device complexity
2Ease of manufacture
If a two-part locking member manufactured by additive manufacturing is used, then manufacturing flexibility is improved, but the locking mechanism still requires external instruments
Solution Approach 1:
The pressure member engages the receiving part through a latching connection that allows self-locking without external instruments. The design enables the rod or locking member to directly actuate the pressure member, making the system self-sufficient during operation
3Reliability
If a pressure element with spring element and detent connection is used, then provisional locking is achieved, but the mechanism requires external instruments for actuation
Solution Approach 1:
The pressure member is configured to be directly actuated by the rod or locking member without requiring external instruments. The latching connection between the pressure member and receiving part enables automatic engagement and provisional locking through the natural insertion and tightening process
Solution Approach 2:
The pressure member is pre-configured with an actuating portion that protrudes above the first end of the receiving part, allowing it to be engaged and actuated in advance during the insertion process. This preliminary configuration enables provisional locking before final tightening
4Area of stationary object
If the actuating portion protrudes above the first end of the receiving part, then the required lateral space for instrument engagement is reduced, but the device structure becomes more complex
Solution Approach 1:
The actuating portion extends in the axial direction above the first end of the receiving part, utilizing the vertical dimension rather than requiring lateral space. This dimensional transition allows engagement from the axial direction, reducing the lateral footprint while maintaining functionality
Data Source
AI summary
A coupling device includes a receiving part with an accommodation space for accommodating a head of a bone anchoring element, an opening, and a recess forming two legs for receiving a rod, and a pressure member arranged at least partially in the accommodation space. The pressure member is adjustable from a first configuration where a topmost end of the pressure member is at a first axial position and the head is pivotable in the accommodation space to a second configuration where the topmost end of the pressure member is at a second axial position below the first axial position and the pressure member provisionally lock the heads. At the second configuration, a latching connection is formed to prevent the pressure member from being adjusted back towards the first configuration. The latching connection is releasable to adjust the pressure member from the second configuration back towards the first configuration.