Locking Pin Plate Assembly with Self-Locking U-Pin Mechanism
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Solution Overview
Problem
Existing bone fracture fixation methods using screws can weaken small bone fragments and fail due to inadequate thread purchase, especially in poor quality bone, and pin plate designs often lack sufficient angular stability and are cumbersome to manufacture and use.
Innovation Solution
A locking pin plate assembly with a U-shaped pin that automatically self-locks into the plate upon insertion, providing stability against axial and angular movement without the need for additional instrumentation or complex surgical techniques, and featuring a design that avoids protrusion into soft tissues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If screws are used to secure bone fragments to the plate, then fixation strength is improved, but small bone fragments are weakened and may fragment further due to the required hole size
Solution Approach 1:
The invention extracts the threading function from the fixation element. Instead of using threaded screws that require large holes, the patent uses smooth pins that pass through the bone fragment and lock into the plate, eliminating the need for threads and reducing hole size requirements.
Solution Approach 2:
The locking mechanism is inverted from the conventional approach. Rather than the bone fragment holding the screw through threads, the plate actively locks the pin in place through a locking mechanism that engages with the pin, reversing the traditional load-bearing relationship.
2Strength
If standard bone screws are used, then compression of bone fragments is achieved, but fixation fails in poor quality bone due to inadequate thread purchase
Solution Approach 1:
The invention removes the threading component entirely from the system. The fixation element is a smooth pin without threads, eliminating the dependency on thread purchase in the bone. The locking function is transferred to the plate's locking mechanism instead.
Solution Approach 2:
The locking mechanism in the plate serves as an intermediary that provides the necessary fixation reliability. Instead of relying on threads to engage with poor quality bone, the locking mechanism mediates the connection between the pin and plate, ensuring secure fixation regardless of bone quality.
3Object-affected harmful factors
If pin plates are used to avoid bone fragmentation, then bone fragment integrity is improved, but angular stability is insufficient and additional instrumentation is required
Solution Approach 1:
The invention merges the functions of pin fixation and angular stabilization into a single integrated locking mechanism. The locking mechanism simultaneously prevents axial movement and constrains angular movement of the pin, eliminating the need for separate instrumentation.
Solution Approach 2:
The locking mechanism is designed to perform multiple functions: it prevents axial movement of the pin, constrains angular movement, and provides secure fixation. This multi-functional design eliminates the need for additional components or instrumentation.
4Stability of the object's composition
If pin plates with tabs or crimping are used to secure pins, then axial movement is limited, but manufacturing complexity and surgical procedure complexity increase
Solution Approach 1:
The locking mechanism is designed to be self-activating. When the pin is inserted into the plate, the locking mechanism automatically engages without requiring external tools, crimping, or additional surgical steps. The system serves itself by automatically securing the pin in place.
Solution Approach 2:
The invention extracts the complex manufacturing steps (tabs, crimping) from the design. The locking mechanism is integrated into the basic structure of the plate and pin, eliminating the need for separate tabs or crimping operations during manufacturing or surgery.
5Ease of operation
If pins extend out of the plate to allow insertion, then pin insertion is enabled, but soft tissue irritation and tendon rupture occur
Solution Approach 1:
The invention inverts the sequence of locking and protrusion. Instead of the pin protruding and then being locked, the locking mechanism engages first during insertion, and only after locking does the pin become flush with the plate surface. This ensures the pin is secured before it can cause tissue irritation.
Solution Approach 2:
The locking action is performed preliminarily during the insertion process itself. As the pin is being inserted, the locking mechanism automatically engages, securing the pin before it can protrude and irritate soft tissues. The flushing action occurs after locking is complete.
Data Source
AI summary
A lockable pin plate assembly which has a pin plate adapted to be secured to stable bone and provided with pin holes for pins for pinning an unstable bone fragment. One or more pin holes are engageable by pins of an integral U-pin. The pins have stop surfaces thereon which are resiliently displaced when the pins are seated to automatically and self-lock the pin and the pin plate to oppose withdrawal and backing out of the pins from the pin plate. In a preferred embodiment, each pin of the U pin has a leading portion and a trailing portion, the leading portion being of smaller diameter to pass freely through an elliptical hole in the pin plate whereas the trailing portion is of larger size to become locked in the pin hole as it is advanced therein.