Modular Vertebral Osteosynthesis Head With Rotating Lock Ring
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Solution Overview
Problem
Existing osteosynthesis devices, such as pedicle screws, often require complex multi-part constructions that compromise mechanical stability and increase manufacturing costs, and are difficult to mount when the bone anchor shaft diameter exceeds the fork head opening diameter, leading to potential disassembly and premature implant failure.
Innovation Solution
A modular osteosynthesis device with a U-shaped fork head and a locking ring that allows for easy assembly and disassembly, accommodating bone anchors of various diameters, and enables temporary clamping to convert polyaxial screws to monoaxial screws during surgery, using a locking ring that rotates to secure the bone anchor in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a multi-part construction with grip chuck is used to mount fork head from distal side, then mounting flexibility is improved, but mechanical stability deteriorates and device complexity increases
Solution Approach 1:
The invention divides the mounting process into two stages: initial insertion with the fork head open (legs deflected outward) to accommodate various bone anchor diameters, followed by locking with the locking ring to secure the bone anchor. This segmentation allows mounting flexibility while maintaining mechanical stability through the locking mechanism.
Solution Approach 2:
The fork head legs are designed to be deflectable (dynamic) rather than fixed, allowing them to open outward for easy insertion of bone anchors with different diameters, then be locked in position by the locking ring. This dynamic capability provides mounting flexibility without compromising the mechanical stability of the final assembled structure.
2Adaptability or versatility
If bone anchor shaft diameter is larger than fork head opening diameter, then adaptability is improved, but mounting difficulty increases
Solution Approach 1:
The fork head legs are designed to be deflectable outward, creating a larger opening that can accommodate bone anchor shafts with diameters larger than the closed fork head opening. This dynamic opening capability provides adaptability to various bone anchor sizes while maintaining easy mounting by simply deflecting the legs outward during insertion.
Solution Approach 2:
The locking ring is designed to be mounted around the spherical head receiving area of the fork head, with the bone anchor head nested within the spherical seat formed by the fork head legs. This nested arrangement allows the bone anchor to be securely held within the fork head structure after insertion.
3Adaptability or versatility
If temporary locking mechanism is added to convert polyaxial screws to monoaxial screws, then surgical flexibility is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The locking ring serves multiple functions: it locks the bone anchor in the spherical head receiving area, provides temporary locking to convert polyaxial screws to monoaxial screws during surgery, and maintains structural integrity. This multi-functionality achieves surgical flexibility without significantly increasing device complexity, as it uses a single component rather than multiple separate mechanisms.
4Ease of manufacture
If as few components as possible are used, then manufacturing cost is reduced, but adaptability deteriorates
Solution Approach 1:
The deflectable fork head legs provide adaptability to various bone anchor diameters without requiring multiple different fork head sizes or additional components. The simple mechanism of deflecting legs outward and locking with a single locking ring achieves versatility while maintaining low component count and manufacturing cost.
Solution Approach 2:
The locking ring serves multiple functions including securing the bone anchor, providing temporary locking capability, and maintaining structural integrity. This multi-functionality reduces the need for additional specialized components, thereby lowering manufacturing costs while maintaining adaptability.
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 stable mounting of bone anchors, reduces component count, minimizes manufacturing costs, and allows for greater flexibility in surgical procedures by enabling temporary clamping and conversion to monoaxial fixation, enhancing mechanical stability and reducing the risk of implant failure.
Implementation Method 1
a form fit is created between the maximum outer cylindrical contour of the fork head and the smallest inner cylindrical contour of the locking ring
Implementation Method 2
the spherical head receiving area is compressed in such a way that the bone anchor is clamped in the spherical seat in an angle-stable manner
Data Source
AI summary
An osteosynthesis device for treating the spine is disclosed including a fork head which is U-shaped in a side view, has two fork legs in the proximal direction with an internal thread, and in which a connecting rod can be received, and a locking element is guided in the internal thread, and the fork head has a spherical head receiving area and is detachably connected to a bone anchor, and the bone anchor is pivotably mounted in the spherical seat of the spherical head receiving area, wherein the fork head has slots which are open in the distal direction at the spherical head receiving area and at least two deflectable legs are thereby formed, and a locking ring mounted at least partially around the spherical head receiving area.