Retrograde Intramedullary Nail Relief Structures for Proximal Fixation
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Solution Overview
Problem
Retrograde intramedullary nails face challenges in targeting and fixing fractures at the proximal regions of the femur due to stress concentrations and deflection issues at the leading end, particularly as nail length increases, making it difficult to insert fixation members accurately.
Innovation Solution
The retrograde intramedullary nail features a leading portion with locking holes and relief formations to reduce stress concentrations, along with an aiming assembly for precise targeting and insertion of fixation members, allowing for effective fixation at proximal femur regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the nail length is increased to provide sufficient coverage from intercondylar to subtrochanteric region, then the fixation coverage is improved, but the stress concentration and deflection at the leading end worsen
Solution Approach 1:
The patent applies local quality by providing relief formations (such as relief grooves or notches) specifically at the leading end portion of the nail where stress concentrations occur. This localized structural modification reduces stress concentration at the critical leading end region without compromising the overall nail length needed for fixation coverage from the intercondylar to subtrochanteric region.
2Length of moving object
If the nail length is increased to provide sufficient coverage from intercondylar to subtrochanteric region, then the fixation coverage is improved, but the deflection at the leading end worsens
Solution Approach 1:
The patent applies local quality by providing relief formations (such as relief grooves or notches) specifically at the leading end portion of the nail where stress concentrations occur. This localized structural modification reduces stress concentration at the critical leading end region without compromising the overall nail length needed for fixation coverage from the intercondylar to subtrochanteric region.
3Reliability
If locking holes are positioned to target proximal femur fractures, then the fixation effectiveness is improved, but the insertion difficulty worsens due to stress and strain
Solution Approach 1:
The patent applies preliminary action by pre-positioning the locking holes at specific locations and orientations during nail manufacturing, designed to align with target fracture sites in the proximal femur. This preliminary configuration allows surgeons to directly insert fixation members through the pre-aligned locking holes without requiring complex real-time adjustment, thereby maintaining fixation effectiveness while simplifying the insertion procedure.
4Reliability
If locking holes are positioned to target proximal femur fractures, then the fixation effectiveness is improved, but the insertion difficulty worsens due to manufacturing tolerances
Solution Approach 1:
The patent applies local quality by providing relief formations (such as relief grooves or notches) specifically at the leading end portion of the nail where stress concentrations occur. This localized structural modification reduces stress concentration at the critical leading end region without compromising the overall nail length needed for fixation coverage from the intercondylar to subtrochanteric region.
Data Source
AI summary
A retrograde intramedullary nail for insertion in the medullary canal of a femur includes a body that is elongate and defines a leading end and a trailing end spaced from each other at a length sufficient to extend from an intercondylar region at least to a subtrochanteric region of the femur. The body further defines a leading portion that extends to the leading end. The leading portion defines at least one locking hole configured to receive a fixation member. The at least one locking hole defines a central hole axis that is oriented to extend through the neck and head of the femur.