Cross Screw Bone Fixation Device for Femoral Neck Fractures

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Solution Overview

Problem

Current bone fracture fixation technologies for femoral neck fractures, such as cannulated screws, dynamic hip screws, and femoral neck systems, face issues like femoral neck shortening, rotation of the femoral head, screw cutout, and avascular necrosis, with high complication rates and failure rates up to 30%.

Innovation Solution

The development of a device with a main screw and cross screw system that includes features like a removable screw head, a slot to prevent lateral movement, a telescoping mechanism, and extendible hooks to secure the fracture site, along with biocompatible materials like polymers and metals, to address the challenges of femoral neck fractures by preserving length, controlling rotation, preventing screw cutout, and minimizing hardware volume within the bone.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If cannulated screws are used to fix femoral neck fractures, then the procedure is simple and quick, but the failure rate is high (up to 30%) due to screw cutout, rotation, and shortening

Engineering Contradiction:

Improvesimplicity of procedureVSAvoidfailure rate

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent combines multiple fixation functions into a single integrated device that incorporates both vertical and transverse screw components, eliminating the need for separate cannulated screws while providing enhanced stability and preventing the complications (cutout, rotation, shortening) that caused high failure rates in traditional single-screw approaches

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The device allows controlled movement between the main screw and cross screw through a slot mechanism, enabling dynamic adjustment during healing while maintaining overall structural integrity. This dynamic capability prevents rigid fixation failures while keeping the procedure relatively simple

Inventive Principle:

Principle #15Dynamics

2Reliability

If dynamic hip screw (DHS) is used to fix femoral neck fractures, then screw cutout may be prevented, but surgical time increases, blood loss increases, and healthy bone must be removed

Engineering Contradiction:

Improveprevention of screw cutoutVSAvoidsurgical time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The device segments the fixation function into two independent screw components (main screw and cross screw) that work together, allowing prevention of screw cutout through distributed load bearing without requiring the extensive bone removal and complex plate structure of DHS, thereby reducing surgical time and blood loss

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cross screw provides localized reinforcement at the critical fracture site where cutout is most likely to occur, while the main screw provides overall fixation. This localized quality enhancement prevents cutout without requiring the extensive modifications to healthy bone that DHS demands

Inventive Principle:

Principle #3Local quality

3Stability of the object's composition

If femoral neck system (FNS) is used to prevent complications, then some stability is improved, but femoral neck shortening, rotation, and cutout still occur with considerable complication rates

Engineering Contradiction:

Improvefracture stabilityVSAvoidcomplication rate

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The device uses asymmetric positioning and orientation of the cross screw relative to the main screw, creating optimal load distribution that prevents the symmetric failure modes (shortening, rotation, cutout) that plague conventional systems. The asymmetric design provides enhanced stability without the high complication rates of FNS

Inventive Principle:

Principle #4Asymmetry

4Strength

If larger quantities of hardware are used to secure the fracture, then fixation strength may be improved, but the risk of avascular necrosis increases due to greater hardware volume in the bone

Engineering Contradiction:

Improvefixation strengthVSAvoidrisk of avascular necrosis

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The dynamic slot mechanism allows the cross screw to move within a controlled range, distributing mechanical stresses more evenly across the fracture site. This dynamic load distribution maintains fixation strength while reducing peak stresses that would require excessive hardware volume, thereby lowering AVN risk

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS20230355287A1Bone fracture fixation device

Publication Date: 2023.11.09 STABILIZ ORTHOPAEDICS INC

AI summary

A device for securing a fractured bone together includes a main screw configured to be driven through a bone fracture, where the main screw engages a removable screw head. Another device secures a fractured bone together and includes a main screw driven through a bone fracture where the main screw includes a slot configured to engage a cross screw therethrough, where the slot includes a system that prevents lateral movement of the main screw relative to the cross screw. Yet another includes a main screw with a main portion and a movable portion, where the movable portion moves within the main portion, and where one of the main portion or movable portion includes threads configured to engage bone. And another device includes a main peg with a hook that: extends from a channel through the peg configured to engage bone.