Biphasic Bone Plate Straight Slot Undercut Design
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Solution Overview
Problem
Existing biphasic bone plates require complex and costly manufacturing processes due to their Ω-shaped slot design, which limits the production of small slot widths and increases the risk of catastrophic failure under unphysiological loading conditions.
Innovation Solution
A bone plate with a straight slot manufactured in a single step using standard wire-erosion or waterjet cutting processes, featuring an undercut feature shifted away from the lower plate surface, allowing for the production of small slot widths without assembling different parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an Ω-shaped slot design is used to provide resistance against tensile forces and valgus bending, then the bone plate's mechanical resistance is improved, but the manufacturing complexity and cost increase significantly
Solution Approach 1:
The slot is segmented into three distinct sections (lower, central, upper) with different functional characteristics. The lower section provides mechanical resistance through its Ω-shaped base, while the central and upper sections facilitate controlled motion. This segmentation allows each section to be optimized independently for its specific function, resolving the contradiction between mechanical strength and manufacturing simplicity.
Solution Approach 2:
The slot design transitions from a two-dimensional planar feature to a three-dimensional structure with varying cross-sections along its length. The Ω-shaped base in the lower section creates vertical dimensionality that provides mechanical resistance, while the cylindrical sections in the central and upper portions enable lateral motion. This dimensional transition allows the slot to achieve both strength and manufacturability.
2Reliability
If an Ω-shaped slot design is used to control interfragmentary motion, then the bone healing outcome is improved, but the production time and cost increase
Solution Approach 1:
The slot design incorporates dynamic characteristics that allow it to adapt its behavior based on loading conditions. At low functional loading, the slot permits required interfragmentary motion (0.5 mm) to promote secondary bone healing. At higher magnitudes of functional loading, the slot closes to limit motion to a maximum, preventing healing complications. This dynamic response is achieved through the specific geometry of the Ω-shaped base and cylindrical sections, which are manufactured in a single process step.
3Reliability
If the slot width is reduced to less than 0.3 mm to avoid overstimulation of the fracture, then the healing complications are avoided, but the manufacturing precision requirements increase
Solution Approach 1:
The slot design applies different quality characteristics to different sections. The lower section has an Ω-shaped base that provides mechanical resistance and controls motion at the fracture site, while the central and upper sections have cylindrical shapes that facilitate smooth movement. The width of the slot is precisely controlled at the lower surface (less than 0.3 mm) to avoid overstimulation, while the upper sections have larger dimensions that are easier to manufacture with standard precision.
4Manufacturing precision
If the lower section and central/upper sections are manufactured separately to achieve the orthogonal cylinder arrangement, then the slot geometry precision is improved, but the device assembly complexity increases
Solution Approach 1:
The manufacturing process merges the creation of the lower section, central section, and upper section into a single integrated operation. The wire-erosion or waterjet cutting process is capable of producing the complex three-dimensional slot geometry with orthogonal cylinder arrangements in one continuous pass, eliminating the need for separate manufacturing steps and subsequent assembly. This merging maintains geometric precision while simplifying the overall manufacturing process.
Data Source
AI summary
Bone plate (1) with a lower surface (2), an upper surface (3), a maximum thickness measured between the lower and upper surfaces a left lateral surface (4), a right lateral surface (5), a longitudinal axis (6) and a plurality of plate holes (7) miming from the lower surface to the upper surface, the bone plate further having a slot (8) in the lower surface extending from the left lateral surface to the right lateral surface having a width measured in a plane parallel to the longitudinal axis and a central plane (16) between the lateral surfaces, wherein (i) the hollow space defined by the slot extends in the form of a straight cylinder from the left lateral surface to the right lateral surface and (ii) the slot comprises an undercut feature (9) limiting the opening of the slot when the bone plate is bent longitudinally in a direction aimed at widening the slot.