Variable Angle Bone Fixation via Hourglass Plate Holes
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Solution Overview
Problem
Traditional locked bone fixation assemblies are cumbersome and require multiple components to achieve a surgeon-selected angle of bone screws relative to the fixation device, making them tedious to manipulate during surgery.
Innovation Solution
A bone fixation device with hourglass-shaped holes, featuring a combination of a partial sphere and frustoconical holes, and a bone screw with a threaded spherical head, allowing for single-action locking at variable orientations without the need for rings or bushings, using only two components: the plate and screws.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional polyaxial systems with bushings or rings are used to achieve variable angle locking, then the screw can be locked at different degrees of angulation, but the device becomes cumbersome and requires multiple components increasing operational complexity
Solution Approach 1:
The patent merges the bushing and ring components into a single integrated hourglass-shaped hole structure. The hourglass hole combines the functions of both the bushing (for variable angle insertion) and the ring (for locking), eliminating the need for separate components while maintaining the polyaxial capability to lock screws at various angles relative to the plate.
Solution Approach 2:
The patent extracts and eliminates the bushing and ring components from the traditional polyaxial system, retaining only the essential hourglass-shaped hole in the plate. This extraction simplifies the device by removing unnecessary intermediate components while preserving the core functionality of variable angle screw insertion and locking.
2Adaptability or versatility
If multiple components (bushing, ring, expansion head screw) are used to achieve polyaxial locking, then variable angle insertion is possible, but the surgical procedure becomes tedious and time-consuming
Solution Approach 1:
The hourglass-shaped hole is pre-formed in the plate during manufacturing, incorporating the variable angle insertion geometry and locking features in advance. This preliminary preparation eliminates the need for intraoperative assembly of multiple components, allowing the surgeon to directly insert and lock the screw in a single surgical motion.
Solution Approach 2:
By combining the bushing and ring functions into a single hourglass hole, the patent reduces the number of assembly steps required during surgery. The integrated structure allows for rapid insertion and locking without the tedious manipulation of separate components, significantly reducing surgical time.
3Adaptability or versatility
If traditional multi-component assemblies are used, then variable angle locking is achieved, but the manipulation during surgery becomes cumbersome
Solution Approach 1:
The patent merges the functions of multiple components (bushing, ring, expansion head screw) into a single integrated hourglass-shaped hole structure. This integration simplifies manipulation during surgery by eliminating the need to handle and assemble multiple separate components, while still providing the freedom to select various angles for screw insertion.
Data Source
AI summary
A bone fixation system including a fixation device having an upper surface, a lower surface and at least one opening extending therethrough and defining a first axis substantially perpendicular to the upper surface, the opening including a plurality of isolated protrusions formed on an inner surface thereof and a bone engaging member insertable through the opening at a selected angle of orientation relative to the first axis, the bone engaging member having a threaded head portion, wherein upon tightening of the bone engaging member, the threaded head portion of the bone engaging member mates with one or more protrusions of the opening to lock the bone engaging member to the plate at the selected angle of orientation relative to the first axis, and wherein the protrusions exhibit the same pitch as the threads on the bone engaging member prior to insertion of the bone engaging member in the opening.