Intramedullary Nail Endcap Driver with Nested Retention Pin

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Solution Overview

Problem

Existing systems for fixing fractured bones, particularly in the femur, face challenges in efficiently and securely engaging an endcap within the channel of an intramedullary nail for internal fixation.

Innovation Solution

A system comprising a driver with a handle and shaft, a retention pin with threading, and an endcap with a head portion and body configured to engage the intramedullary nail, allowing for reversible locking and secure insertion of the endcap into the nail's channel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional driver system is used to engage the endcap, then the endcap can be inserted into the intramedullary nail channel, but the risk of accidental disengagement during implantation increases

Engineering Contradiction:
Improveendcap retentionVSAvoiddriver system structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The retention pin is nested within the shaft channel, sliding freely within it during insertion and then engaging the endcap head portion. This nested configuration allows the retention mechanism to be integrated into the existing driver structure without adding external components, thereby improving reliability while minimizing increased complexity

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The retention pin transitions from a static component to a dynamic one that can slide longitudinally within the shaft channel. During insertion, the pin moves freely to allow endcap engagement, then locks in place to prevent disengagement. This dynamic behavior provides reliable retention while maintaining a relatively simple driver system structure

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If the retention pin is made fixed in the shaft, then the driver structure is simplified, but the ability to reversibly lock and unlock the endcap is lost

Engineering Contradiction:
Improveendcap engagement controlVSAvoidretention pin mechanism
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The driver system is segmented into distinct functional components: the shaft for guiding the endcap, the retention pin for locking/unlocking, and the handle for operator control. This segmentation allows each component to perform its specific function efficiently, making the engagement control intuitive while keeping the overall mechanism manageable in complexity

Inventive Principle:
Principle #1Segmentation

3Ease of operation

If the driving element is exposed at the distal end of the shaft, then engagement with the endcap head portion is facilitated, but the risk of misalignment increases

Engineering Contradiction:
Improvedriving element engagementVSAvoidalignment accuracy
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The guidewire is inserted through the intramedullary nail channel and endcap lumen beforehand to establish the correct alignment path. The driver and endcap are then guided along this pre-established path, ensuring precise alignment between the driving element and head portion while keeping the driving element accessible for engagement

Inventive Principle:
Principle #10Preliminary action

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 system enables efficient and secure engagement of the endcap within the intramedullary nail, providing stable fixation of the bone while minimizing the risk of accidental disengagement during implantation.

Implementation Method 1

The head portion of the end cap comprises threading configured to threadedly engage a corresponding threading of the retaining pin

Methodology Applied
Scientific EffectThreading: Screw

Data Source

PatentEP4027924B1Driver and system for threaded intramedullary nail retaining endcaps
Publication Date: 2025.04.30 DEPUY SYNTHES PROD INC
  • EP4027924B1 patent drawingFigure 1A~2
  • EP4027924B1 patent drawingFigure 1B~1D
  • EP4027924B1 patent drawingFigure 1E~1F

AI summary

A driver for engaging an endcap of an intramedullary nail. The driver includes a handle extending along a longitudinal axis of the driver from a proximal end to a distal end. The handle having a handle channel extending longitudinally therethrough. The driver also includes a shaft extending through the handle channel from a proximal end to a distal end along the longitudinal axis. The shaft having a shaft channel extending longitudinally therethrough. The distal end of the shaft extends distally from the handle. The distal end of the shaft forms a driving element to be inserted into a head portion of the endcap. The driver further includes a retention pin slidably received in the shaft channel. The retention pin extends also extends along the longitudinal axis. The distal end of the retention pin is configured to reversibly lock the shaft to the head portion of the endcap.