Radial Bone Rasp Milling for Controlled Graft Particle Size
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Solution Overview
Problem
Conventional bone mills fail to effectively morselize both cortical and cancellous bone, often damaging the bone structure and producing unsuitable particle-size distributions for bone grafting, leading to inefficiencies and increased costs in surgical procedures.
Innovation Solution
A radial bone-milling apparatus with a rasp system featuring negative relief angles and angled side-cutting edges, combined with a power-driving module and centrifugal forces, is designed to produce morselized bone with a predictable particle-size distribution, utilizing a hollow radial rasp and a rotor with a cavity for efficient bone chip collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional powered bone mills use high-speed rotating blades to mill bone, then milling speed increases, but bone tissue structure is damaged and heat is generated causing necrosis
Solution Approach 1:
The patent replaces the conventional high-speed rotating blade cutting mechanism with a low-speed impactor system that uses controlled mechanical impacts to fracture bone into morsels. This substitution maintains milling productivity while eliminating the heat generation and tissue damage caused by high-speed friction and cutting forces.
Solution Approach 2:
The patent fundamentally changes the operating parameters from high-speed rotation to low-speed impact, and from continuous cutting to intermittent fracturing. This parameter change allows bone to be morselized efficiently without generating harmful heat or damaging the osteogenic tissue structure.
2Stability of the object's composition
If manually operated bone mills are used to preserve bone tissue structure, then tissue structure is preserved, but excessive manual force is required and productivity is low
Solution Approach 1:
The patent employs a self-feeding mechanism where the impactor automatically advances bone material into the milling zone and ejects finished morsels through vibration and gravity. This eliminates the need for continuous manual feeding and force application, significantly increasing productivity while maintaining tissue structure preservation through controlled low-speed impact.
Solution Approach 2:
The patent incorporates vibration mechanisms to facilitate the ejection of morselized bone from the milling chamber and to maintain continuous operation without manual intervention. The vibration assists in separating finished morsels from the bone material being processed, enhancing productivity while preserving tissue integrity.
3Manufacturing precision
If coffee grinder-style bone mills are used to achieve fine particle size, then particle size is reduced, but bone structure is mashed and heat energy damages particles
Solution Approach 1:
The patent uses periodic impact cycles where the impactor strikes bone material at controlled intervals to progressively reduce particle size. This periodic fracturing action achieves the desired fine particle size distribution without the continuous mashing and heat generation that occurs in coffee grinder-style mills, preserving bone tissue structure throughout the process.
4Productivity
If saw-crusher style bone mills are used to process bone, then large bone slivers are produced, but these are not suitable for bone grafting
Solution Approach 1:
The patent employs multiple impactors or a multi-faceted impactor that simultaneously fractures bone into multiple smaller pieces in a single processing cycle. This segmentation approach produces the required fine particle size distribution suitable for bone grafting while maintaining high processing capacity, unlike saw-crushers that produce oversized slivers.
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 solution consistently provides morselized corticocancellous, cancellous, or cortical bone with preserved tissue structures and appropriate particle-size distribution, enhancing the efficiency and effectiveness of bone grafting procedures while reducing manual effort and minimizing waste.
Implementation Method 1
a power-driving module and centrifugal forces, is designed to produce morselized bone with a predictable particle-size distribution
Data Source
AI summary
Rasp systems for controlled milling of cortical, cancellous or combinations disclosed. The disclosed rasp system may provide morselized bone with predetermined particle-size distribution for automatic milling apparatus. The rasp systems comprises a rasp for cutting material and a push surface to effect directing and sweep the material over surface of the rasp for controlled milling material disclosed. The bone-cutting tooth having side cutters disclosed. In addition, radial rasp systems with self-generating centrifugal forces for pushing material against the rasp surface for automatic milling apparatus disclosed. Furthermore, embodiments can include a battery-powered autoclaveable milling apparatuses for automatic milling cortical, cancellous or combinations of bone material utilizing said radial rasp systems disclosed.