Self-Countersinking Bone Screw to Prevent Screw Head Prominence

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Solution Overview

Problem

Orthopedic implants, such as intramedullary nails, often experience screw promulgation, where the screw head protrudes from the bone, leading to tissue irritation and the need for additional surgeries to remove the screws, and current methods to countersink screws require additional 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 markings to guide proper 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 promulgationVSAvoidadditional instrumentation 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 clinical outcome of preventing screw promulgation.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The bone screw is designed to perform its own countersinking function through self-contained cutting flutes and tapered geometry. When the screw is inserted and driven into the bone, the cutting flutes automatically create the countersink cavity and the tapered neck portions guide the screw head to a flush position, eliminating the need for external countersinking tools or 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 countersinking capability is built into the screw design itself, so the countersink cavity is created during the screw insertion process rather than requiring a preliminary separate drilling step. The cutting flutes and tapered geometry perform the countersinking action as the screw is being driven into the bone, saving surgical time while still preventing tissue irritation.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If the 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 screw design incorporates localized tapered neck portions and cutting flutes at specific locations to achieve countersinking only where needed at the bone surface interface. The main body of the screw maintains its standard threaded structure for secure fixation, while the localized modifications enable the head to be flush with the bone surface, preventing tissue irritation without complicating the overall insertion process.

Inventive Principle:

Principle #3Local quality

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 bone fixation and tactile feedback for surgeons during implantation.

Implementation Method 1

The one or more cutting flutes include a distal end and a proximal end, the distal end of the cutting flute being positioned closer to the distal end portion of the bone screw than the distal end of the neck portion so that, in use, the distal end of the one or more cutting flutes contacts a patient's bone prior to the distal end of the neck portion

Methodology Applied

Scientific EffectCutting:

Implementation Method 2

The neck portion includes a distal end and a proximal end, the neck portion configured to provide a transition from the shaft portion to the enlarged head portion, the neck portion including a minor outer diameter that tapers from a minor outer diameter of the shaft portion towards the enlarged head portion

Methodology Applied

Scientific EffectTapered geometry:

Data Source

PatentUS20260020888A1Self-countersinking bone fastener and method for countersinking a bone fastener used in connection with an orthopedic implant

Publication Date: 2026.01.22 SMITH & NEPHEW INC

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.