Polyaxial Bone Plate Assembly for Irregular Surfaces
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Solution Overview
Problem
Existing bone plates face challenges in securely stabilizing irregular bone surfaces due to their regular geometric designs, which can cause collateral damage to cortical and cancellous bone, and may leave defects when removed, limiting subsequent surgical options.
Innovation Solution
A polyaxial bone plate assembly with adjustable pads and a locking mechanism that can rotate and translate to fit congruently on irregular bone surfaces, achieving fixation in cortical bone without damaging it, and allowing for secure locking without invasive penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a regular geometric bone plate is used, then the device structure is simple, but it cannot securely stabilize irregular bone surfaces
Solution Approach 1:
The bone plate incorporates adjustable pads that can be repositioned and locked at different locations along the plate's length, allowing the device to dynamically adapt to varying bone surface geometries. The pads are movable relative to the plate body and can be secured at multiple positions to match irregular bone contours.
Solution Approach 2:
The bone plate is divided into multiple functional segments including the plate body, individual adjustable pads, and locking mechanisms. Each pad can be independently positioned and locked, allowing segmented adaptation to different portions of the irregular bone surface rather than requiring the entire plate to conform to a single geometry.
2Strength
If invasive fixation elements (screws, pegs) are used, then fixation strength is achieved, but collateral damage to cortical and cancellous bone occurs
Solution Approach 1:
The invention introduces a non-invasive intermediary mechanism where the adjustable pads make contact with the bone surface to provide fixation. Instead of penetrating the bone with screws or pegs, the pads press against the bone surface, distributing fixation forces without causing invasive damage to cortical or cancellous bone structures.
3Reliability
If invasive fixation elements are used, then fixation is achieved, but defects are left when removed limiting subsequent options
Solution Approach 1:
The invention extracts the fixation function from invasive penetrating elements and relocates it to non-invasive surface-contacting pads. This allows the fixation mechanism to be removed without leaving permanent defects in the bone, preserving the bone's integrity and future surgical options while maintaining reliable fixation during the treatment period.
4Strength
If cortical bone fixation is attempted with traditional elements, then strong load bearing is achieved, but alignment with cortical surface is required making seating difficult
Solution Approach 1:
The invention changes the fixation approach from point-contact penetrating elements to surface-contacting pads that distribute load across a larger area of the cortical bone. This parameter change in contact geometry allows the pads to conform to and seat on irregular cortical surfaces without requiring precise alignment, while still achieving strong load-bearing capacity through distributed pressure.
Data Source
AI summary
A bone plate assembly including at least one bone plate, polyaxially adjustable fixation elements and a polyaxially adjustable locking mechanism. A first plate includes at least one polyaxial element for lockable connection with a fixation pad, and a connection feature which allows the plate to translate and polyaxially rotate relative to the locking mechanism. A second plate includes at least one polyaxial element for connection with a fixation pad and a connection feature for non-rotatable connection with the locking mechanism. The locking mechanism allows translation and polyaxial adjustment of the first plate relative to the second plate and locks the first and second plates via a taper lock. The fixation pad includes a deflectable spacer configured to prevent premature locking of the pad. Methods for implantation of the bone plate assembly between two bone structures are disclosed. Instrumentation for implantation, compression and locking of the bone plate assembly is disclosed.