Bone Fixation Device with Secondary Compression for Femoral Neck Fractures
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Solution Overview
Problem
Existing orthopedic fixation devices for femoral neck fractures face issues with migration, rotation, and insufficient holding power, leading to complications such as femoral head cut-out and thread stripping, especially in geriatric patients with fragile proximal cortical bone.
Innovation Solution
A bone fixation device with a helical distal anchor and a moveable proximal anchor that can be axially advanced to secure the fracture, featuring a tubular sleeve with graduations and retention structures to resist proximal movement, allowing for independent tensioning without relocating the distal anchor, thereby providing improved locking force and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional compression screw assemblies are used for femoral neck fractures, then the fracture can be compressed and fixed, but the device migrates proximally towards the hip joint weight bearing surface causing femoral head cut-out
Solution Approach 1:
The fixation device is divided into multiple functional segments: a proximal portion with compression and fixation features, and a distal portion with anchoring features. This segmentation allows each portion to be optimized for its specific function while working together to provide stable fixation without migration.
Solution Approach 2:
The invention introduces a rotational dimension to the proximal portion, allowing it to rotate within the distal portion. This rotational capability enables the device to adapt to different bone geometries and provides an additional degree of freedom for achieving proper fixation without migration.
2Strength
If externally threaded implants are used to grip the femoral head bone, then the implant can be secured to the bone, but large stress concentrations are generated during implantation leading to thread stripping
Solution Approach 1:
The thread geometry parameters are modified to reduce stress concentrations. The threads are designed with specific pitch, angle, and profile characteristics that distribute stress more evenly during implantation, preventing thread stripping while maintaining secure bone grip.
3Adaptability or versatility
If movable arms are attached to the main body of the implant, then the implant can adapt to bone geometry, but all fatigue loading is concentrated at the attached ends causing large bending moments
Solution Approach 1:
The movable arms are segmented from the main body and connected through a rotational joint. This segmentation allows the arms to move independently for bone geometry adaptation while the rotational connection distributes fatigue loading away from concentrated stress points.
4Ease of operation
If the proximal anchor is axially advanced to compress the fracture, then compression can be applied without relocating the distal anchor, but the device complexity increases
Solution Approach 1:
The proximal anchor is designed with axial movability relative to the distal anchor, creating a dynamic structure that allows compression application without relocating the distal anchor. This dynamic capability simplifies the compression process while maintaining device functionality.
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 device effectively resists migration and rotation, providing stable fixation and minimizing complications like femoral head cut-out and thread stripping, enabling timely recovery and weight-bearing in patients with femoral neck fractures.
Implementation Method 1
A distal anchor of the fixation device is rotated to secure the fixation device to the second fragment
Implementation Method 2
the proximal anchor is axially advanced to engage the first fragment
Data Source
AI summary
Disclosed is a fracture fixation device, for reducing and compressing fractures in a bone. The fixation device includes an elongate body. An axially moveable proximal anchor is carried by the proximal end of the fixation device and comprises a tubular sleeve that includes a plurality of graduations positioned on an outer surface of the tubular sleeve. The device is rotated into position across the femoral neck and into the femoral head, and the proximal anchor is distally advanced to lock the device into place. In certain embodiments, the elongated body includes a distal anchor with a distal cutting tip.