Negative-Rake Burr for Selective Cartilage Removal in Joints
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Solution Overview
Problem
Conventional surgical burrs used in minimally invasive surgery (MIS) arthrodesis procedures struggle to differentiate between cartilage and subchondral bone during removal, often inadvertently cutting into the subchondral bone due to the lack of tactile feedback and the burrs' effectiveness in cutting through both tissues.
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 the subchondral bone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional burrs are used for cartilage removal, then the burr cutting action is effective, but the surgeon cannot detect when the burr has cut through the cartilage and is contacting the subchondral bone
Solution Approach 1:
The patent applies feedback by designing the burr with specific geometric parameters (negative rake angle between -10 to -50 degrees, specific diameter range of 2 to 4 mm) that create distinct tactile feedback signals. When the burr contacts the subchondral bone, the surgeon perceives a change in resistance or vibration pattern, providing real-time feedback about the transition from cartilage to bone tissue.
Solution Approach 2:
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 alter the cutting characteristics to enable preferential cartilage removal while maintaining distinguishable tactile feedback when contacting the underlying bone.
2Productivity
If the burr cutting action is made more effective, then cartilage removal is improved, but the burr removes undesirable amounts of subchondral bone
Solution Approach 1:
The patent modifies the burr parameters by implementing a negative rake angle between -10 to -50 degrees and a diameter of 2 to 4 mm. These parameter changes optimize the cutting action for cartilage while reducing the burr's ability to penetrate the harder subchondral bone, thereby minimizing harmful bone removal.
Solution Approach 2:
The patent applies local quality by designing the burr with specific geometric characteristics that create different cutting behaviors for different tissues. The negative rake angle and diameter combination enable the burr to effectively cut soft cartilage while requiring significantly more force to penetrate the harder bone, allowing selective removal of cartilage only.
3Manufacturing precision
If visual observation of joint surfaces is performed, then cartilage removal precision is improved, but the procedure complexity increases
Solution Approach 1:
The patent applies self-service by designing the burr to provide its own feedback mechanism through tactile signals. The burr's geometric parameters create inherent tactile feedback that guides the surgeon during cartilage removal, eliminating the need for additional visual observation systems or complex monitoring equipment.
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 the 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.