Bone Screw Tip Geometry for Low-Torque Pedicle Placement

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Solution Overview

Problem

Existing bone screws face challenges in achieving quick and accurate placement, particularly in pedicle screws, which can complicate surgical procedures and require additional equipment for correct screw placement.

Innovation Solution

The bone screws feature a distal tip with cutting edges having a positive rake angle and a leading surface extending at an acute angle, along with trailing surfaces angled to minimize drag, facilitating efficient insertion into bone.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional bone screw designs are used, then the screw can be placed in bone, but the torque and downward force required for advancement are high, making the procedure time-consuming and difficult

Engineering Contradiction:

Improveease of screw advancementVSAvoidtorque and downward force required

Core Design Contradiction:

Ease of operationVSForce

Solution Approach 1:

The patent changes the geometric parameters of the screw tip by introducing a positive rake angle (5-30 degrees) on the leading surface and specific trailing surface angles (30-60 degrees). These parameter changes optimize the cutting geometry to reduce the force required for bone advancement while maintaining effective bone engagement.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies curvature to the tip geometry by creating a rounded or awl-shaped tip with specific surface angles rather than sharp edges. This curved geometry distributes the insertion force more effectively and reduces the peak torque required during advancement.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Productivity

If conventional screw designs are used, then the screw can engage bone, but frictional drag during insertion is high, reducing surgical efficiency

Engineering Contradiction:

Improvesurgical efficiencyVSAvoidfrictional drag

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent optimizes the thread geometry parameters including pitch, depth, and angle to minimize frictional contact during insertion. The specific configuration of leading and trailing surfaces reduces the normal force between screw and bone, thereby reducing frictional drag and energy loss during the insertion process.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If pedicle screws are used for spinal procedures, then the spine can be stabilized, but accurate placement is difficult and may require additional equipment

Engineering Contradiction:

Improvescrew placement accuracyVSAvoidequipment required

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The rounded or awl-shaped tip geometry with specific surface angles allows the screw to self-center and follow the drill hole more accurately during insertion. This curved tip design provides inherent guidance that reduces placement errors and minimizes the need for complex guidance equipment while maintaining high placement accuracy.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Data Source

PatentUS12471974B2Bone screw

Publication Date: 2025.11.18 MEDOS INT SARL

AI summary

Various bone screws configured to be implanted into bone and methods of use are provided. In an exemplary embodiment, a bone screw is provided with an elongate shank and a head with a drive feature configured to couple with a driver tool for being advanced into bone and a threaded shank. The screw can have a distal end or tip that has one or more cutting edges thereon configured to cut bone as the bone screw is inserted into bone.