Surgical Drill Bit Segmentation for Hole Precision

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Solution Overview

Problem

Current surgical drills used in osteosynthesis procedures often unintentionally widen hole diameters due to high-speed cutting and vibrations, leading to thermal damage and inconsistent hole sizes, which compromises the performance of bone screws.

Innovation Solution

A surgical drill bit design featuring an elongate body with a distal cutting segment and a guiding segment, including helical flutes with distinct outer profiles to maintain hole size precision and reduce thermal damage, allowing the drill bit to operate effectively at high speeds without substantial cutting into the bone wall.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the drill operates at high speeds to improve productivity, then drilling efficiency is improved, but the hole diameter becomes inconsistent and thermal damage occurs

Engineering Contradiction:

Improvedrilling speedVSAvoidhole diameter consistency

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The drill bit is divided into two distinct segments: a cutting segment with a first outer profile and a guiding segment with a second outer profile. The cutting segment performs the actual bone cutting, while the guiding segment maintains hole diameter consistency by contacting the hole wall without cutting, thereby resolving the contradiction between high-speed drilling and precise hole diameter control

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different segments of the drill bit are given different geometric properties: the cutting segment has cutting edges angled to remove bone material, while the guiding segment has a cylindrical outer profile that contacts the hole wall at a single point or narrow band, allowing it to guide the drill without widening the hole, thus maintaining local functional differentiation to achieve both speed and precision

Inventive Principle:

Principle #3Local quality

2Productivity

If the drill operates at high speeds to improve productivity, then drilling efficiency is improved, but thermal damage to bone segments occurs

Engineering Contradiction:

Improvedrilling speedVSAvoidthermal damage to bone

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The harmful cutting function is extracted from the guiding segment and confined only to the cutting segment. The guiding segment is designed to contact the hole wall without cutting, thereby eliminating the source of frictional heat generation in the guiding portion and reducing overall thermal damage to the bone while maintaining high drilling speed

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The outer profile parameters of the drill bit are changed along its length: the cutting segment has a larger outer diameter and cutting edges optimized for material removal, while the guiding segment has a smaller, precisely controlled outer diameter that contacts the hole wall minimally. This parameter variation allows high-speed operation with reduced frictional heating

Inventive Principle:

Principle #35Parameter changes

3Productivity

If the drill operates at high speeds to improve productivity, then drilling efficiency is improved, but the hole wall is unintentionally cut and widened

Engineering Contradiction:

Improvedrilling speedVSAvoidhole diameter accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of having the entire drill bit surface engage with the hole wall (which causes widening), the invention inverts the approach by having only a minimal portion of the guiding segment contact the wall, while the majority of the surface is recessed. This inverted geometry prevents unwanted cutting and maintains precise hole diameter control

Inventive Principle:

Principle #13The other way round (Inversion)

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 drill bit maintains hole diameters within 6% of the desired size even at high speeds, reducing thermal damage and ensuring consistent hole sizes for secure bone screw fixation.

Implementation Method 1

The second leading edge can be spaced from the central axis by a second length that is less than the first length and the second bearing surface is spaced from the central axis so as to define a second radius that is substantially equal to the first radius

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentEP2836134B1Surgical drill bits

Publication Date: 2017.05.17 SYNTHES GMBH

Figure 1
Figure 2A~2B
Figure 2C~2E

AI summary

A surgical drill bit (10) can include a body portion (30) that defines a central axis (C) that extends along a first direction. The body portion can be separated along the first direction into a distal cutting segment (70), and a guiding segment (74). The body portion can include a helical flute (78) that winds about the central axis. The helical flute can define a first outer profile along the cutting segment and a second outer profile along the guiding segment, the first outer profile has a first leading edge (90) and a first bearing surface (98) and the second outer profile has a second leading edge (120) and a second bearing surface (128. The first leading edge can be configured to cut into bone and can be spaced from the central axis by a first length (LL1). The second leading edge can be spaced from the central axis by a second length (LL2) that is less than the first length.