Blade-like Osteosynthetic Device with Twisted Wings
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Solution Overview
Problem
Existing blade-like implants for weakened bone structures, such as osteoporotic bone tissue, lack sufficient pull-out strength and fatigue resistance, and existing combinations with bone screws are not suitable for pedicle insertion due to structural weaknesses and biomechanical incompatibilities.
Innovation Solution
A blade-like bone anchor with twisted surfaces and a threaded bushing that engages with the cortical pedicle, combined with a polyaxial tulip head, to absorb bending and axial forces, featuring thickened wing portions and mechanical stops to enhance fatigue strength and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a blade-like implant is used to provide greater stability against bending loads, then stability is improved, but pullout strength is limited
Solution Approach 1:
The patent combines a blade-like implant with a bone screw to create a hybrid osteosynthetic device. The blade portion (with twisted wing surfaces) provides stability against bending loads, while the integrated bone screw provides pullout strength. This merging of two different implant types resolves the contradiction by allowing both functions to work simultaneously in a single device.
Solution Approach 2:
The implant uses a composite structure combining blade-like elements (for bending resistance) with threaded screw elements (for pullout resistance). The device integrates two different functional components with complementary mechanical properties to achieve both stability and pullout strength that neither component could provide alone.
2Strength
If a combination of blade with bone screw is used to provide both stability and pullout strength, then both mechanical advantages are achieved, but the implant is not suitable for insertion into the pedicle
Solution Approach 1:
The blade portion of the implant features locally twisted wing surfaces with specific interlacing patterns adapted for pedicle anatomy. The twisting angle and orientation are optimized for the specific geometry of the pedicle, allowing the device to be inserted dorsally through the pedicle into the vertebral body while maintaining its mechanical advantages.
Solution Approach 2:
The implant incorporates a spherical segment in the head region that allows polyaxial adjustment. This spherical interface enables the blade-screw combination to be oriented at various angles relative to the pedicle axis, making the device adaptable to different pedicle orientations and anatomical variations while maintaining structural integrity.
3Ease of operation
If a window for transport screw is provided in the blade area, then transport function is enabled, but fatigue strength is significantly reduced
Solution Approach 1:
The transport function is separated from the load-bearing blade structure by providing a distinct longitudinal bore through the shaft. The window in the blade area is positioned and sized to minimize structural compromise while still allowing access for the transport screw. The driver element and threaded bushing are designed as separate components that can be inserted through this minimized opening.
Solution Approach 2:
A threaded bushing is introduced as an intermediary component between the driver element and the blade structure. This bushing distributes loads more evenly and provides a controlled interface for the transport function, reducing stress concentrations that would otherwise occur at the window opening and thereby preserving fatigue strength.
4Ease of manufacture
If the distal portion of the blade is positioned vertically in the vertebral body, then insertion is simplified, but bending loads cannot be absorbed at the distal implant area
Solution Approach 1:
The twisted wing surfaces create a curved, interlaced pattern that naturally follows the load paths in the vertebral body. The twisting angle is designed so that when inserted dorsally, the distal portion of the blade achieves optimal orientation for absorbing bending loads while the overall insertion path remains relatively straightforward.
Data Source
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AI summary
The invention relates to an osteosynthetic device (10) for fixing bone components and bone fragments, in particular vertebrae, consisting of a shaft (13), which extends along a central axis (103) and thereby defines a distal direction (102) and a proximal direction (101). The shaft (13) has at least one blade region (14) having a first wing (15) and a second wing (16) and proximally (101) adjoins a neck region (12) and further along has a head (11) having at least one ball segment (111). The shaft (13) has a central and continuous cannulisation opening (18) with a diameter (183). At least one window (17) with an opening width (171) is provided in the blade region (14), and the window (17) communicates with the cannulisation opening (18). The head region (11) has an opening (112) with an opening diameter (113), which likewise communicates with the cannulisation opening (18), wherein the diameter of the cannulisation opening (183) is smaller than the opening width of the window (171), and the diameter of the cannulisation opening (183) is likewise smaller than the opening diameter at the head (113). The shaft (13) with the blade region (14), the neck region (12) and the head (11) with the ball segment (111) is formed as a whole in one piece.