Patient-Specific Orthopaedic Surgical Instruments Using 3D Printed Negative Contours

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Solution Overview

Problem

Current orthopaedic surgical instruments are generic and reusable, which can lead to inefficiencies and inaccuracies in joint replacement surgeries as they do not account for the unique anatomy of individual patients, potentially resulting in suboptimal surgical outcomes.

Innovation Solution

Customized patient-specific orthopaedic surgical instruments are designed using 3D printing technology, such as Direct Metal Laser Sintering (DMLS), to create instruments with negative contours that match the patient's bone anatomy, including cutting guides and drill guides, reducing the need for intra-operative guesswork and improving precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If generic reusable orthopaedic surgical instruments are used, then device complexity is reduced and ease of manufacture is improved, but manufacturing precision and measurement precision deteriorate due to inability to account for unique patient anatomy

Engineering Contradiction:

Improvealignment accuracyVSAvoidinstrument customization

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Patient-specific instruments are designed and manufactured before surgery based on pre-operative imaging data (CT or MRI scans). The instruments incorporate patient-specific anatomical surface contours that are determined and fabricated in advance, allowing precise alignment and positioning during surgery without requiring complex intraoperative adjustments.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patient-specific instruments include bone-contacting surfaces that are negative impressions or copies of the patient's actual bone surface geometry. These copied surfaces enable precise registration and alignment by matching the unique anatomical features of the individual patient's bone structure.

Inventive Principle:

Principle #26Copying

2Measurement precision

If customized patient-specific instruments are used, then manufacturing precision and surgical accuracy are improved, but device complexity and loss of time in manufacturing increase

Engineering Contradiction:

Improvesurgical accuracyVSAvoidmanufacturing time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The invention changes the manufacturing approach from traditional metal machining to additive manufacturing (3D printing). This parameter change in the manufacturing process enables complex patient-specific geometries to be produced more efficiently, reducing manufacturing time while maintaining high precision. The additive process can directly create complex surfaces and internal structures that would be time-consuming or impossible to manufacture using conventional methods.

Inventive Principle:

Principle #35Parameter changes

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

These customized instruments allow for precise alignment and resection of bones, reducing surgical complexity and improving the accuracy of joint replacements by directly matching the patient's anatomy, thereby enhancing surgical outcomes and reducing recovery time.

Implementation Method 1

The base plate has a bone-facing surface including a customized patient-specific negative contour configured to receive a corresponding positive contour of the patient's bone

Methodology Applied

Scientific EffectNegative contour matching: Geometry