J-Shaped Extraction Instrument for Controlled Revision Arthroplasty
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Solution Overview
Problem
Current orthopedic instruments used in revision arthroplasty are inadequate for safely and efficiently removing prosthetic components due to their inability to deliver controlled forces in tight spaces, leading to potential injury and excessive bone loss.
Innovation Solution
Development of extraction instruments with unique shapes and configurations, such as J-shaped and L-shaped designs, that provide leverage and mechanical advantage, allowing for controlled force application and reduced risk of injury, along with a reverse force hammer for safer bone-prosthesis bond disruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional orthopedic instruments (thin flexible osteotomes, solid single end cutting osteotomes, jiggly saws, oscillating saws, reciprocating saws) are used to remove implanted prosthetic components, then the surgeon can attempt to disrupt the bone-to-prosthesis bond, but the instruments are too broad, too thick and/or otherwise unable to fit within the tight confines of a typical revision arthroplasty, challenging the surgeon's abilities to deliver strong but controlled forces in a variety of directions and limiting unwanted residual movement of the cutting edge immediately after disruption occurs
Solution Approach 1:
The extraction instrument is divided into distinct functional segments: a long thin shaft for access, a bridge component for positioning, and an extraction blade for force application. This segmentation allows each component to be optimized independently - the shaft can be sufficiently thin to access tight spaces while the blade can be designed to deliver controlled extraction forces.
Solution Approach 2:
The instrument introduces a bridge component that extends perpendicular to the shaft axis, creating a three-dimensional configuration. This allows the extraction blade to be positioned at a distance from the shaft, enabling the surgeon to apply forces in multiple directions and achieve mechanical advantage while maintaining access through tight spaces.
2Reliability
If traditional osteotomes are used to disrupt the bone-to-prosthesis bond, then the cutting edge can be driven between the prosthetic component and host bone, but when the bond is broken the residual axial force causes a sudden and somewhat uncontrolled movement of the cutting surface towards the body of the patient and important anatomical structures, increasing the risk of inadvertent injury
Solution Approach 1:
Instead of applying force in the traditional anterior-to-posterior direction that risks injury to posterior structures, the extraction blade is designed to apply force in the opposite direction (posterior-to-anterior or laterally), pulling the prosthesis away from vulnerable anatomical structures. The bridge configuration enables this reverse force application.
Solution Approach 2:
The bridge component acts as an intermediary between the shaft and the extraction blade, providing a pivot point and mechanical advantage. This intermediary structure allows the surgeon to control the direction and magnitude of forces applied to the prosthesis, reducing uncontrolled movements and improving safety.
3Loss of substance
If traditional instruments are used to remove pre-existing implants which have been in the patient for a number of years, then the bone-to-prosthesis bond must be disrupted, but maximization of bone preservation is especially important and the use of known instruments may result in the removal of excess quantities of the patient's essential bone during a revision arthroplasty, leaving undesirably large cavities or bone gaps
Solution Approach 1:
The extraction blade is designed with specific local qualities - a thin profile for minimal bone contact, a specific geometry for targeted force application at the bone-prosthesis interface, and a length that extends beyond the prosthesis to engage the bone interface without requiring excessive force that would damage surrounding bone.
Solution Approach 2:
The instrument changes the parameters of force application - distributing forces over a larger area through the bridge configuration, applying forces in multiple directions rather than single-axis impact, and controlling the magnitude and direction of disruptive forces to minimize bone loss while achieving prosthesis removal.
4Strength
If the three-dimensional configuration of prosthetic implants is optimized for functionality and strong bone-to-prosthesis bond, then the bone-contacting surface comprises complex shapes with curved, angled and flat surfaces of various dimensions, but this makes it difficult to gain the necessary exposure of the bonded interface between natural bone and implanted component
Solution Approach 1:
The complex three-dimensional geometry of the prosthesis is addressed by segmenting the extraction approach - the long thin shaft provides access to deep interfaces, the bridge provides positioning flexibility, and the extraction blade can be oriented to engage specific portions of the bone-prosthesis interface, allowing systematic exposure and removal.
Solution Approach 2:
The bridge component extends the instrument into a third dimension perpendicular to the shaft, allowing the extraction blade to access bonded interfaces that are not reachable by linear instruments. This enables engagement of complex three-dimensional prosthesis geometries from multiple angles.
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 instruments enable quicker and safer revision arthroplasty procedures by minimizing the risk of accidental injury and excessive bone removal, facilitating controlled force application and improved bone preservation.
Implementation Method 1
extraction instruments with unique shapes and configurations, such as J-shaped and L-shaped designs, that provide leverage and mechanical advantage
Implementation Method 2
allowing for controlled force application and reduced risk of injury
Data Source
AI summary
Extraction instruments and systems for use in revision arthroplasty are provided. The extraction instruments are shaped and configured to fit within the typically tight confines in which revision arthroplasty is performed, and to enhance the surgeon's control over the axis, quantum and speed of the force that is required be applied to disrupt a bone-to-prosthesis bond. This enables completion of a revision arthroplasty to proceed more quickly, and with reduced risk that unwanted movements might cause accidental injury to nearby vital structures.