Negative-Rake Burr Geometry for Selective Cartilage Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional surgical burrs used in minimally invasive surgery (MIS) arthrodesis procedures struggle to differentiate between cartilage and subchondral bone during removal, leading to unintended cutting of the subchondral bone due to the lack of tactile feedback and the burrs' effectiveness in cutting both tissues similarly.
Innovation Solution
A burr with a negative rake angle between −10 to −50 degrees, a diameter of 2 to 4 mm, and a rotational speed not exceeding 10,000 rpm is used to preferentially remove cartilage, providing tactile feedback when it contacts subchondral bone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional burrs are used for cartilage removal, then cartilage can be removed effectively, but subchondral bone is unintentionally removed due to lack of tactile feedback
Solution Approach 1:
The patent changes the geometric parameters of the burr by specifying a negative rake angle between -10 to -50 degrees and a diameter of 2 to 4 mm. These parameter modifications create differential cutting characteristics that allow the burr to effectively remove cartilage while providing tactile feedback when contacting subchondral bone, preventing unintended bone removal.
Solution Approach 2:
The patent utilizes tactile feedback as a control mechanism. The modified burr geometry creates a noticeable change in resistance or tactile sensation when the burr transitions from cutting cartilage to contacting subchondral bone. This feedback allows the surgeon to recognize the boundary between cartilage and bone and adjust cutting pressure accordingly, preventing excessive bone removal.
2Productivity
If burrs with high cutting effectiveness are used, then cartilage removal is efficient, but tactile feedback becomes indistinguishable between cartilage and bone
Solution Approach 1:
By precisely controlling the burr's geometric parameters (negative rake angle of -10 to -50 degrees and diameter of 2 to 4 mm), the patent creates a cutting profile that maintains high effectiveness for cartilage removal while generating distinct tactile feedback signals. The specific parameter range ensures the burr cuts cartilage efficiently but produces noticeable resistance changes when encountering the denser subchondral bone.
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 method effectively removes cartilage while minimizing contact with subchondral bone, offering clear tactile feedback to surgeons to avoid unnecessary bone removal.
Implementation Method 1
maneuvering the burr within the joint against the cartilage while rotating the burr at a speed not more than about 10,000 revolutions per minute (rpm), wherein the burr comprises a plurality of cutting flutes that have a negative rake angle of −10 to −50 degrees
Data Source
AI summary
Disclosed is a method for preferentially removing cartilage from a bone in a joint that is effective at removing the cartilage while minimizing any removal of the cortical bone.