Anatomical Fibula Nail Geometry for Rotationally Stable Fixation
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Solution Overview
Problem
Existing intramedullary nails for fibular fractures lack anatomical fit, leading to issues such as micro-motion, pain, necrosis, and prolonged healing due to inadequate contact with the bone structure, and require complex bone preparation.
Innovation Solution
An intramedullary fibula nail with a non-cylindrical distal portion and a cylindrical proximal portion, featuring anchoring structures like threaded, serrated, and suture-activated mechanisms to enhance stability and alignment, along with a guide reamer system for precise canal preparation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cylindrical intramedullary nail is used to fit the medullary canal, then the nail can be easily inserted and positioned, but the nail does not provide sufficient contact with the bone structure leading to micro-motion and pain
Solution Approach 1:
The intramedullary nail transitions from a cylindrical proximal portion to a non-cylindrical distal portion with asymmetric geometry. The distal portion includes a first maximum width in a medial-lateral plane and a second maximum width in an anterior-posterior plane, where the second width is larger than the first width. This asymmetric configuration provides enhanced contact with the fibular bone structure while maintaining ease of insertion through the cylindrical proximal portion.
2Reliability
If the outer diameter of the intramedullary nail is selected for the minimum inside diameter of the space, then the nail fits through the canal, but portions of the nail are not in contact with the surrounding bone structure
Solution Approach 1:
The nail design incorporates dimensional variation by transitioning from a cylindrical proximal portion to a non-cylindrical distal portion with different width measurements in different planes. The distal portion has a first maximum width in the medial-lateral plane and a second maximum width in the anterior-posterior plane, utilizing multiple dimensions to maximize bone contact surface area while maintaining compatibility with the medullary canal dimensions.
3Stability of the object's composition
If a metal rod is placed inside the medullary canal to stabilize the fracture, then the fracture can be aligned and stabilized, but the rod may rotate within the canal causing inadequate stabilization
Solution Approach 1:
The non-cylindrical distal portion with asymmetric geometry (different widths in medial-lateral and anterior-posterior planes) provides inherent rotation resistance within the medullary canal. This asymmetric configuration prevents rotational movement of the nail while maintaining fracture alignment and stabilization, eliminating the need for additional anti-rotation mechanisms.
4Stability of the object's composition
If bone plates are attached directly on the bone surface to fixate fractures, then the bone fragments can be stabilized, but substantial surgical exposure is required resulting in lengthy and painful healing
Solution Approach 1:
The intramedullary nail divides the fixation function into two segments: a cylindrical proximal portion for easy insertion and positioning within the medullary canal, and a non-cylindrical distal portion for enhanced bone contact and stabilization. This segmentation allows the nail to be inserted through a minimal incision without requiring substantial surgical exposure of the bone surface, reducing soft tissue trauma and healing time.
Data Source
AI summary
An intramedullary fibula nail kit includes an intramedullary fibula nail. The intramedullary fibula nail includes a proximal portion configured to be positioned within a medullary canal of a fibula, and a distal portion configured to be positioned within the medullary canal of the fibula. The distal portion defines a non-cylindrical cross-section.