Self-Countersinking Bone Screw for Flush IM Nail Fixation

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Solution Overview

Problem

Existing orthopedic implants, such as intramedullary nails, face the issue of screw promulgation, where the screw heads protrude from the bone, leading to tissue irritation and the need for additional surgeries to remove them, and current countersinking methods require extra instrumentation and steps.

Innovation Solution

A self-countersinking bone screw with cutting flutes and a tapered neck portion that allows the screw head to be flush with the bone surface without pre-drilling, using a screwdriver with depth markings for precise insertion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If pre-drilling countersink holes in the patient's cortex is performed to countersink the bone screw head, then screw promulgation is eliminated, but additional instrumentation and steps are required

Engineering Contradiction:
Improvescrew promulgationVSAvoidinstrumentation and steps
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent combines the countersinking function with the bone screw itself by integrating cutting flutes and a tapered neck portion directly into the screw structure. This eliminates the need for separate countersinking instrumentation while achieving the same beneficial effect of preventing screw promulgation.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The bone screw is designed to perform its own countersinking function through its integrated cutting flutes and tapered geometry. As the screw is inserted and driven into the bone, it automatically creates the countersink hole and positions its head flush with the bone surface without requiring external countersinking tools or additional surgical steps.

Inventive Principle:
Principle #25Self-service

2Object-affected harmful factors

If pre-drilling countersink holes is performed to enable countersinking of bone screws, then tissue irritation is prevented, but surgical time is increased

Engineering Contradiction:
Improvetissue irritationVSAvoidsurgical time
Core Design Contradiction:
Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The bone screw automatically creates its own countersink hole during insertion through its integrated cutting flutes and tapered design, eliminating the need for separate pre-drilling steps. This self-service capability prevents tissue irritation while reducing surgical time by consolidating multiple operations into a single insertion action.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The cutting flutes and tapered geometry are pre-configured into the screw structure before implantation, enabling the countersinking action to occur automatically during the insertion process itself, rather than requiring separate preliminary drilling operations.

Inventive Principle:
Principle #10Preliminary action

3Ease of operation

If the bone screw head extends away from the bone surface, then insertion is simpler, but tissue irritation occurs requiring second surgery

Engineering Contradiction:
Improveinsertion simplicityVSAvoidtissue irritation
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The bone screw automatically positions its head flush with the bone surface during insertion through its self-countersinking mechanism, eliminating the need for complex pre-drilling procedures while preventing tissue irritation that would otherwise require a second surgical intervention.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent merges the countersinking function with the insertion process itself, allowing the screw to be driven into the bone while simultaneously creating the countersink hole and positioning the head flush with the surface, thereby maintaining insertion simplicity while preventing harmful tissue irritation.

Inventive Principle:
Principle #5Merging (Combining)

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 solution minimizes screw promulgation and eliminates the need for additional instrumentation, providing secure implantation and tactile feedback for surgeons, ensuring the screw head is flush with the bone surface.

Implementation Method 1

one or more cutting flutes extending from the enlarged head portion towards the distal end portion

Methodology Applied
Scientific EffectCutting: Abrasion

Implementation Method 2

The tapered outer surface is configured as a linear taper

Methodology Applied
Scientific EffectTactile feedback: Friction

Data Source

PatentEP4312838B1Self-countersinking bone fastener
Publication Date: 2026.04.15 SMITH & NEPHEW INC
  • EP4312838B1 patent drawingFigure 1
  • EP4312838B1 patent drawingFigure 2A~2C
  • EP4312838B1 patent drawingFigure 3A

AI summary

Disclosed herein is a self-countersinking bone screw and a system and a method for countersinking a bone screw or fastener used in connection with an orthopedic implant such as, for example, an intramedullary nail. The bone screw includes one or more cutting features configured to self-countersink the head of the screw. The system and method utilize instrumentation including a plurality of markings or indicia configured to indicate a position of the head of the screw relative to an outer surface of the patient's bone. In use, the method enables a surgeon to quickly and easily countersink one or more bone screws used to couple an IM nail to a patient's bone without requiring additional instrumentation to form a countersunk hole in the patient's bone.