Polyaxial Cross Connector with Translation Member and Locking Mechanism
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Solution Overview
Problem
Current spinal fixation devices lack a quick and efficient mechanism to securely couple elongate fixation elements with adjustability for polyaxial and rotational alignment, which is essential for accommodating geometric variations in clinical settings.
Innovation Solution
A device comprising a first and second connector member with a translation member, allowing polyaxial movement and a locking mechanism using a set screw to secure the fixation elements with an interference fit, enabling simultaneous locking of the connector members relative to the translation member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a cross connector with adjustability is provided to accommodate variations from geometrical alignment, then the adaptability is improved, but the device complexity increases
Solution Approach 1:
The connector is divided into distinct functional segments: a body portion with a polyaxial bore for receiving the rod, a locking mechanism with movable locking members, and resilient arms for securing the rod. This segmentation allows each component to perform its specific function independently, achieving polyaxial adjustability while maintaining manageable complexity through modular design.
Solution Approach 2:
The locking mechanism incorporates movable locking members that can transition between locked and unlocked positions, and resilient arms that can flex to accommodate rod insertion. This dynamic design enables the connector to adapt to different rod positions and orientations while providing secure fixation once positioned, resolving the contradiction between adaptability and complexity.
2Reliability
If a locking mechanism is added to secure the fixation element and lock polyaxial movement, then the reliability is improved, but the ease of operation deteriorates
Solution Approach 1:
The locking mechanism combines multiple functions into a single integrated assembly: the locking members both secure the fixation element within the polyaxial bore and simultaneously lock the polyaxial movement of the connector body. This merging of functions ensures reliable fixation while simplifying the operation to a single locking action rather than multiple separate steps.
Solution Approach 2:
The resilient arms automatically engage with the fixation element when inserted into the polyaxial bore, providing self-securing functionality. The locking members then simply need to be positioned to lock the polyaxial movement, rather than requiring complex manual adjustment or multiple fastening operations, thus improving ease of operation while maintaining reliability.
3Reliability
If multiple locking members are used to secure both the fixation element and lock polyaxial movement, then the reliability is improved, but the productivity decreases
Solution Approach 1:
The resilient arms are pre-configured to automatically engage and secure the fixation element as it is inserted into the polyaxial bore. This preliminary securing action occurs before the final locking step, so that when the locking members are actuated, both the element securing and polyaxial movement locking are accomplished simultaneously in a single operation, maximizing productivity without compromising reliability.
Solution Approach 2:
The locking members are designed to perform multiple functions simultaneously: they secure the fixation element in place and lock the polyaxial movement of the connector body. This multi-functionality allows a single locking action to achieve both security objectives, eliminating the need for separate locking steps and thereby improving surgical installation efficiency.
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
The solution provides a secure, efficient, and adjustable coupling of spinal fixation elements, facilitating quick installation during surgical procedures while ensuring stability and alignment, thus enhancing the strength and stability of spinal fixation constructs.
Implementation Method 1
at least one of the proximal and distal arms resiliently flexing open to accept the first elongate spinal fixation element and flexing back to provisionally receive the first elongate spinal fixation element with the interference fit
Implementation Method 2
threading of the first set screw into the hole moves the proximal and distal arms relative to one another to secure the first elongate spinal fixation element in the engagement portion of the first connector member
Implementation Method 3
the proximal portion of the first connector member includes a sphere and the distal portion of the translation member includes a bore for receiving the sphere to provide the polyaxial movement
Implementation Method 4
A surface of the bore and a surface of the sphere may further include grooves and the other of the surface of the bore and the surface of the sphere includes ridges
Data Source
Figure 1~2
Figure 3~6
Figure 7A~7D
AI summary
A device and method for coupling first and second elongate spinal fixation elements. The device includes first and second connector members, for receiving first and second elongate spinal fixation elements respectively. One or both connector members may include an engagement portion configured and dimensioned to provisionally receive an elongate fixation element with an interference fit. First and second connector members are coupled to a translation member, the translation member operatively associated with at least one connector member to provide for polyaxial movement. At least one locking member is provided to secure a received elongate spinal fixation element in the engagement portion and lock polyaxial movement of the at least one connector member. The translation member may have first and second portions which move relative to each other with translation movement, and a third locking member to lock the translation movement.