Variable Angle Cephalomedullary Nail for Femur Fracture Stability

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Solution Overview

Problem

Conventional cephalomedullary nailing systems face challenges in providing adequate biomechanical stability and predictability for femur fractures, particularly in subtrochanteric and pertrochanteric fractures, due to insufficient locking systems and risk of implant rupture, which can lead to complications like femoral neck collapse and limb length loss.

Innovation Solution

A cephalomedullary nailing system with a variable angle cephalic screw and additional locking screws, featuring a toroidal or double truncated cone channel geometry for enhanced rotational stability and a homogeneous nail support surface, allowing 360° nail rotation and random locking within specific varus-valgus inclination ranges, along with a trochanteric support plate for additional stabilization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional cephalomedullary nailing systems are used, then the basic fixation function is provided, but biomechanical stability and predictability are insufficient

Engineering Contradiction:

Improvebiomechanical stabilityVSAvoidlocking system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The locking system is segmented into multiple independent locking screws that can be positioned at different angles and locations along the nail, allowing distributed stabilization across multiple bone interfaces. This segmentation enables progressive load distribution and enhanced biomechanical stability without requiring a monolithic complex structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The nail geometry is pre-configured with predetermined locking surfaces and angular orientations that facilitate stable fixation before final tightening. The pre-shaped canal and locking mechanisms are designed in advance to guide proper alignment and provide immediate initial stability upon insertion.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If conventional locking systems are used, then basic fixation is achieved, but risk of implant rupture increases

Engineering Contradiction:

Improveimplant failure riskVSAvoidimplant strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The nail incorporates locally optimized geometries at critical stress points, including varied wall thicknesses, reinforcement zones, and angle-specific strengthening features. These local quality modifications address high-stress areas without requiring uniform strengthening throughout the entire implant, reducing overall material stress concentrations and rupture risk.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system utilizes composite construction principles with materials and geometries optimized for specific functional requirements - combining cortical and cancellous bone engagement features, varying material densities in different nail sections, and integrating multiple locking mechanisms that distribute stress across composite structural elements.

Inventive Principle:

Principle #40Composite materials

3Adaptability or versatility

If fixed angle nails are used, then simple insertion is possible, but adaptability to different fracture patterns is limited

Engineering Contradiction:

Improvefracture pattern adaptabilityVSAvoidsystem complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The nail system incorporates dynamic adjustment capabilities allowing post-insertion modification of locking angles and positions. The variable angle locking mechanisms enable adaptation to different fracture patterns and bone geometries after the initial insertion, providing versatility without requiring multiple pre-configured fixed-angle implants.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The nail design integrates multiple functions into a single device - combining cephalic and medullary functions, integrating multiple locking mechanisms for different fracture types, and incorporating both fixed and variable angle capabilities. This multi-functionality provides adaptability across various fracture patterns while maintaining a unified system architecture.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11471201B2Cephalomedullary nailing system of variable angle to treat femur fractures and the utensils used to place the system

Publication Date: 2022.10.18 FERRERO MANZANAL FRANCISCO

AI summary

The cephalomedullary nailing system of this invention contributes to solving three main problems: reduce fractures, improve assembly biomechanics to ensure the load axis is favorable as possible for bony fragments and prevent femoral neck collapse as well as offset and limb length loss, hence avoiding the possibility of reduced abductor power. The system is based on specific screw channel geometry and the placement of an additional locking screw, allowing the nail to turn 360° and facilitating nail insertion through the screw.