Intramedullary Fixation Device With Barbed Arrowhead Heads
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Solution Overview
Problem
Current surgical methods for hammertoe correction using external K-wires face challenges such as non-unions, K-wire migration, loss of fixation, pin tract infections, and bone rotation due to the smooth surface of the wires, necessitating alternative fixation methods for effective bone stabilization and pain relief.
Innovation Solution
An intramedullary fixation device with arrowhead-shaped distal and proximal heads and a rigid body, featuring barbs and undercuts to engage tissue and resist rotational and axial movements, providing secure bone fixation without external exposure, allowing for faster and less invasive implantation procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If external K-wires are used for fixation, then the procedure is simple and external fixation is achieved, but the smooth wire surface causes rotational movement and axial migration of bone
Solution Approach 1:
The fixation device employs an asymmetric arrowhead-shaped distal head with non-circular geometry featuring barbs and undercuts. This asymmetric design prevents rotational movement by engaging the bone cortex in a direction-dependent manner, while the barbs provide directional resistance against axial migration, solving the stability problem without compromising procedural simplicity.
Solution Approach 2:
The invention transitions from a one-dimensional smooth wire to a three-dimensional arrowhead-shaped structure with barbs and undercuts. This dimensional enhancement allows the device to engage the bone in multiple directions simultaneously, providing rotational and axial stability that a simple wire cannot achieve.
2Ease of operation
If external K-wires are used for fixation, then the procedure is minimally invasive, but pin tract infections and loss of fixation occur
Solution Approach 1:
The invention extracts the problematic external portion of the K-wire system by providing a completely intramedullary fixation device. The arrowhead-shaped head and barbed structure are contained entirely within the bone marrow cavity, eliminating pin tracts and their associated infection risks while maintaining the minimally invasive nature of the procedure.
Solution Approach 2:
The intramedullary fixation device acts as an intermediary between the two bone fragments, providing stable internal fixation without requiring external hardware. The barbed arrowhead structure mediates the mechanical connection between bone segments while remaining concealed within the bone, eliminating external infection pathways.
3Ease of manufacture
If smooth K-wires are used for fixation, then the procedure is straightforward, but bone rotation and movement along the wire occur
Solution Approach 1:
The asymmetric arrowhead geometry with barbs and undercuts provides directional engagement with the bone cortex. This design creates mechanical interlocking that resists rotational forces and axial migration, significantly enhancing the strength of fixation compared to smooth wires while maintaining procedural simplicity.
Solution Approach 2:
The curved barbs and undercut contours of the arrowhead shape create a geometry that naturally engages with the cylindrical bone structure. This curved design allows the device to conform to the bone's shape while providing multi-directional resistance to movement, enhancing fixation strength without complicating the insertion procedure.
Data Source
AI summary
An internal intramedullary fixation device for the stabilization of bone in arthrodesis and fractures of the foot and hand is disclosed. During implantation in medullary canals of bones, the device grasps the edges of the canals, stabilizing the bones, internally, during a healing process. The intramedullary fixation device comprises arrow-shaped proximal and distal heads comprising tips and a pairs of wings, the heads being sized to fit within an intramedullary canal of a bone. The intramedullary fixation device also comprises a rigid body defining a longitudinal axis connecting the proximal and distal heads. The rigid body comprises an intermediate portion, a distal neck portion connecting the rigid body to the distal head, and a proximal neck portion connecting the rigid body to the proximal head, the neck portions having a cross-sectional area smaller than a cross-section area of the intermediate portion.