Implantable Device Radially Deformable Ring Locking Mechanism
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Solution Overview
Problem
Existing bone fixation devices face challenges in achieving a low overall height while ensuring reliable locking of anchoring elements, particularly polyaxial bone screws, which require angular stability and decoupling from rotary movement to prevent rotation relative to the implant.
Innovation Solution
The implementation of a locking mechanism with a radially deformable ring element and a conical geometry between the locking element and the anchoring element, allowing for axial force conversion into radial compression to securely fix the anchoring element, enabling polyaxial storage and angular adjustment within a predetermined range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a locking mechanism with ring element is used to lock polyaxial bone screws, then angular stability is improved, but device complexity increases
Solution Approach 1:
The ring element is nested within the opening of the implant, and the locking element is integrated into the implant structure. The bone screw passes through the ring element, creating a nested configuration where the ring element is positioned within the opening and the screw shank passes through the ring. This nesting arrangement provides angular stability while minimizing the overall device complexity by utilizing space efficiently within the implant structure.
Solution Approach 2:
The locking mechanism is segmented into distinct functional components: the ring element that provides angular constraint, the locking element that prevents rotary movement, and the bearing surface that enables polyaxial adjustment. This segmentation allows each component to perform its specific function independently, achieving angular stability through the ring element's conical geometry and the locking element's engagement with the bearing surface, while keeping the overall device design manageable.
2Ease of operation
If the implant height is reduced, then ease of operation is improved, but locking reliability may deteriorate
Solution Approach 1:
The locking mechanism utilizes the third dimension (depth) efficiently by positioning the ring element within the opening and using the bearing surface at the bottom of the opening. The conical geometry of the ring element's inner surface allows it to engage with the bone screw head in a way that converts axial compression forces into radial locking forces, achieving reliable locking within a compact height profile. The locking element engages with the bearing surface to prevent rotary movement while maintaining a low overall implant height.
Solution Approach 2:
The conical geometry of the ring element's inner surface with a specific opening angle (1° to 12°, particularly 2° to 8°) transforms the mechanical interaction between the locking element and the bone screw. This geometric parameter change allows the ring element to be radially compressed by the locking element, creating reliable angular stability and preventing rotary movement while maintaining a compact implant height. The bearing surface geometry also changes the force distribution to ensure reliable locking.
3Adaptability or versatility
If polyaxial adjustment range is increased, then adaptability is improved, but locking reliability may worsen
Solution Approach 1:
The bearing surface acts as an intermediary between the bone screw head and the ring element. It provides a controlled interface that allows polyaxial adjustment within a predetermined range while maintaining reliable locking. The bearing surface geometry enables the bone screw to be positioned at different angles relative to the implant axis before final locking, and then prevents rotary movement once locked, thus mediating between the need for adaptability and locking reliability.
Solution Approach 2:
The locking mechanism transitions from a dynamic state allowing polyaxial adjustment to a static locked state. Before locking, the bone screw can be freely adjusted within a predetermined angular range relative to the implant axis, with the head resting on the bearing surface. After the locking element is activated and radially compresses the ring element, the system becomes static with the ring element preventing both angular movement and rotary movement, thus providing reliable locking while maintaining adaptability during the adjustment phase.
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
This solution achieves a low overall height of the implant, ensures reliable locking of anchoring elements, and allows for angular stability and decoupling from rotary movement, enhancing the fixation of bone fragments and joint replacements.
Implementation Method 1
a radially deformable ring element that can be pressed against the head of the anchoring element by actuating the locking element
Implementation Method 2
the ring element can be radially elastically compressible and/or compressible, in particular by the locking element
Implementation Method 3
a radially outer geometry of the ring element is conical at least in sections, with an opening angle of the conical section being in particular 1° to 12°, in particular 2° to 8°
Implementation Method 4
the head rests directly on the implant, in particular not indirectly via the ring element, rotation of the bearing surface relative to the head when tightening the locking element can be prevented
Data Source
Figure 1~2
Figure 3
AI summary
An implantable device is described, comprising an implant (12), wherein the implant comprises at least one opening (22), at least one anchoring element (14) for fixing the implant to at least one bone, wherein the respective anchoring element comprises a shank (20) and a head (18) and wherein at least a part of the shank can be guided through the respective opening while the head can be seated in the respective opening, and a locking mechanism with a fixation element (16) and a radially deformable annular element(26) that can be pressed against the head of the anchoring element by actuation of the fixation element, in order to fix the head in the opening of the implant. The opening of the implant has a recess (28) having a support surface (24) for the head of the anchoring element.