Angled Bone Fixation Assembly for Uniform Compression and Alignment
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Solution Overview
Problem
Existing bone fixation assemblies, such as screws, plates, and K-wires, fail to provide uniform compression, maintain anatomically correct bone alignment, minimize incision size, reduce soft tissue disruption, and prevent screw head breakage, leading to increased infection risk and reduced effectiveness in procedures like MTP fusion and arthrodesis.
Innovation Solution
A fixation assembly comprising a post member with a tapered connection to a screw member, allowing for multi-point fixation and intraosseous bicortical anchoring, which translates uniform compression and maintains bone alignment, minimizing incision size and soft tissue disruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple screws and plates are used for fixation, then bone fixation strength is improved, but wound closure difficulty and infection risk increase
Solution Approach 1:
The patent combines multiple fixation functions (screw anchoring, plate fixation, and compression) into a single integrated device. The bone fixation device includes a plate with multiple threaded holes that can receive screws, while also incorporating a compression mechanism that applies uniform force across the bone interface, eliminating the need for separate compression devices and reducing hardware profile.
Solution Approach 2:
The device performs multiple functions simultaneously: it provides structural support through the plate, secures bones through threaded screw holes, applies compression across the fracture site, and maintains alignment. This multi-functional design reduces the number of separate implants needed and minimizes soft tissue disruption.
2Strength
If devices with surface prominence (plates or exposed screws) are used, then bone fixation is achieved, but wound closure difficulty increases
Solution Approach 1:
The patent relocates the fixation hardware from the superficial soft tissue layer to the deep intraosseous space. The plate is positioned within the medullary canal or on the inner surface of the bone, with screws anchoring into the bone from the inside. This dimensional relocation eliminates surface prominence that would otherwise interfere with wound closure.
Solution Approach 2:
The device nests the plate and screw assembly within the bone structure itself. The plate fits within the medullary canal or against the inner cortical surface, and screws are inserted through the plate and anchored into the bone, creating a nested configuration that minimizes external profile and soft tissue disruption.
3Strength
If conventional screws are used for MTP fusion, then fixation is provided, but uniform compression and bone alignment are not achieved
Solution Approach 1:
The device incorporates a dynamic compression mechanism that allows adjustment of compression force and distribution. The compression applied by the device can be modified to achieve optimal uniform compression across the bone interface, and the device maintains this compression dynamically during healing, rather than relying on fixed static screw pressure.
Solution Approach 2:
The patent changes the compression parameter from localized point pressure (conventional screws) to distributed uniform pressure across the entire bone interface. The plate's large surface area in contact with the bone, combined with the compression mechanism, transforms the compression distribution parameter to achieve uniform force application, improving alignment and fusion outcomes.
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 fixation assembly provides stable, rigid fixation, maximizes cortical bone contact, reduces hardware profile, and allows early patient mobilization by minimizing incision size and soft tissue disruption, while maintaining bone alignment and preventing screw head breakage.
Implementation Method 1
The screw member is coupled to the post member by advancing the elongated portion of the screw member through the tapered bore of the post member until the tapered bulbous portion of the screw member abuts the tapered bore of the post member
Data Source
AI summary
A fixation assembly for bone fixation and a method for joining bones or bone fragments of a single bone and translating uniform compression to the bones. The fixation assembly comprises a post member coupled to a screw member. The post member comprises a head portion connected to an anchoring portion, wherein the head portion is offset from the anchoring portion by a first angle. The head portion may comprise a curved body annularly extending from a first end to a second end, wherein the first end is separated from the second end by a slot, and wherein the curved body defines a tapered annular bore therein. The anchoring portion comprises a first leg extending from the first end of the curved body and a second leg extending from the second end of the curved body. The screw member comprises a tapered bulbous portion connected to a threaded elongated portion. The screw member is coupled to the post member by advancing the elongated portion of the screw member through the tapered bore of the post member until the tapered bulbous portion of the screw member abuts the tapered bore of the post member thereby creating an interference fit. The first angle of the post member determines the angle of fixation of the post member with respect to the screw member.