Bone Stabilization Implant Using Asymmetric Pegs and Thermoplastic Anchoring
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Solution Overview
Problem
Conventional screw and plate systems for stabilizing separated bone portions after osteotomy or fracture are limited by circular screw cross-sections, reduced load-bearing capability, and the need for thick plates to maintain rigidity, which restricts optimal load distribution and flexibility in design.
Innovation Solution
A method and implant using non-threaded pegs with specific cross-sections for load-bearing functions, connected by a bridge portion and secured with a thermoplastic material that liquefies and solidifies within the bone tissue to provide pull-out retention, allowing for more flexible design and improved load distribution without the need for circular cross-sections or screw threads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If screw and plate systems are used for stabilizing bone portions, then the bone portions can be stabilized, but the load-bearing capability is reduced due to circular cross-section and screw thread constraints
Solution Approach 1:
The patent applies asymmetry by replacing the conventional circular screw cross-section with a non-circular peg cross-section. The peg has a specific asymmetric shape that optimizes load distribution and increases load-bearing capability while eliminating the constraints imposed by circular geometry and screw threads.
Solution Approach 2:
The patent applies local quality by designing the peg with a specific cross-sectional shape tailored for optimal load-bearing in specific directions. The non-circular cross-section allows different portions of the peg to have different structural properties, optimizing strength where needed while reducing material elsewhere.
2Strength
If thick plates are used to maintain rigidity, then the plate stiffness is sufficient, but the plate thickness is larger than necessary and prevents flush implantation with bone surface
Solution Approach 1:
The patent extracts the rigidity function from the thick plate structure by using the peg-bridge system where the bridge portion provides the necessary stiffness while the pegs provide anchorage. This allows the implant to achieve sufficient rigidity with minimal thickness, enabling flush implantation with the bone surface.
Solution Approach 2:
The patent transitions from a two-dimensional plate structure to a three-dimensional peg-bridge assembly. The bridge portion extends in multiple dimensions, providing rigidity through spatial configuration rather than relying on increased thickness in a single dimension.
3Strength
If conventional screws are used for stabilization, then the implant can be secured, but the circular cross-section and screw thread reduce the ratio of load-bearing capability vs. cross-section
Solution Approach 1:
The patent extracts the load-bearing function from the screw thread structure, eliminating the threads entirely. The non-circular peg cross-section provides load-bearing capability through its geometry alone, without requiring threads for mechanical engagement, thus increasing the ratio of load-bearing capability to cross-sectional area.
Solution Approach 2:
The patent replaces the mechanical screw thread system with a geometric interlocking system. The non-circular cross-section of the peg provides mechanical engagement through its shape complementarity with the bone or counter-peg, eliminating the need for threads and improving load-bearing 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 enables more efficient load distribution, reduced bone tissue removal, and cost-effective manufacturing, while providing the necessary stability and flexibility for bone stabilization, allowing for optimal alignment and healing of separated bone portions.
Implementation Method 1
a securing element (4) comprising a material having thermoplastic properties and constituting a form-fit connection between the bone tissue and the securing structures (5, 5.1, 5.2) of the peg and bridge assembly (1) through in situ liquefaction of the material having thermoplastic properties, through penetration of the bone tissue by the liquefied material and through re-solidification of the material having thermoplastic properties in the bone tissue
Data Source
AI summary
An implant for stabilizing two separated bone portions relative to each other an implant includes a peg, a bridge assembly and a securing element. The peg and bridge assembly include at least two peg portions and a bridge portion, wherein the bridge portion is arranged between the peg portions and wherein the peg and bridge portions are rigidly connected. The peg and bridge assembly is positioned relative to the bone portions such that one peg portion extends into the bone tissue of each one of the bone portions and the bridge portion extends across the gap separating the bone portions. The securing element is anchored in the bone tissue of one of the bone portions, its proximal end extending through an opening in an assembly portion extending parallel to a bone surface or across a notch in a proximal edge of an assembly portion.