Bone Cutting Geometry for Stable Reassembly
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Solution Overview
Problem
Conventional bone cutting tools lack precision, leading to unsatisfactory reassembly of bone tissue in reconstructive surgery, with cut portions often shifting or being inadequately shaped, necessitating external fixation and auxiliary constructions.
Innovation Solution
A computer-implemented method for planning a cutting process that computes a cut geometry allowing bone tissue to be reassembled in a specific, stable position by shaping the cut to restrict movement in one or multiple degrees of freedom, using initial and target data obtained through measurements like CT scans, and applying this geometry with a laser-guided robot arm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cutting tools are used to cut bone tissue, then the cutting process is simple and quick, but the precision of the cut is insufficient causing bone portions to shift during reassembly
Solution Approach 1:
The cutting method divides the bone into multiple portions along a planned cut geometry that creates complementary fitting surfaces. These segmented portions are designed to fit together like puzzle pieces, with each cut surface containing geometric features (protrusions, recesses, interlocking patterns) that prevent shifting during reassembly. The segmentation principle transforms a single precision-critical operation into multiple controlled cuts that collectively achieve both precision and stability.
Solution Approach 2:
The cut geometry employs asymmetric designs where the cutting surfaces on different bone portions are non-mirror images but complementary to each other. Features such as asymmetric grooves, angled surfaces, and irregular patterns are created on opposing faces to ensure that only one specific orientation and position allows proper reassembly. This asymmetry eliminates the possibility of incorrect positioning or shifting during surgical reassembly.
2Productivity
If conventional cutting tools are used, then the surgical procedure is faster, but external fixation means are required which increases operation time and complexity
Solution Approach 1:
The invention merges the cutting function with the fixation function into a single integrated process. The cut geometry itself serves dual purposes: it separates the bone portions while simultaneously creating self-aligning and self-locking features that eliminate the need for separate fixation devices. By combining these functions, the surgical procedure achieves both speed (through efficient laser cutting) and stability (through integrated geometric interlocking) without requiring additional fixation steps.
Solution Approach 2:
The bone portions are designed to be self-fixating through their cut geometry. The complementary surfaces with interlocking features automatically align and secure the bone portions in the correct position during reassembly without requiring external fixation means. The structure serves its own fixation needs through carefully designed geometric features that provide mechanical interlocking and positional stability inherent to the cut surfaces themselves.
3Object-affected harmful factors
If conventional cutting tools are used, then the equipment is simpler, but collateral damage to surrounding bone tissue occurs
Solution Approach 1:
The invention replaces conventional mechanical cutting tools with a laser-based cutting system. The laser beam delivers precise energy to the bone tissue, vaporizing or melting the material along the planned cut path with minimal thermal affect to surrounding areas. This substitution of mechanical force with optical/thermal energy enables extremely precise cuts with clean edges and minimal collateral damage to adjacent bone structures, while the controlled energy delivery prevents excessive heat spread.
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
Enables precise and stable reassembly of bone tissue without additional fixation means, minimizing inaccuracies and ensuring the bone is reshaped accurately in the target position, with the cut geometry providing additional contact surfaces for stronger healing connections.
Implementation Method 1
WO 2011/035792 A1 describes a computer assisted and robot guided laser osteotome medical device. This device uses a robot arm guided laser, such as an Er:YAG laser, to cut human or animal bone tissue by photoablating the tissue along a predefined osteotomic line.
Data Source
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AI summary
A method for planning a process of cutting human or animal bone tissue (9) comprises: obtaining initial data of an initial situation of the bone tissue (9); defining target data of a target situation of the bone tissue (9); and computing a cut geometry using the initial data and the target data for cutting the bone tissue (9) apart. The cut geometry comprises a structure being shaped such that the bone tissue (9) is reassemblable in an at least in one degree of freedom distinct manner in the target situation after being cut apart along the cut geometry. By shaping the structure of the cut geometry in accordance with the target situation of the bone the planned cut can be provided with a particular function. I.e., such a functional cut can geometrically define and restrict possible movements of cut apart bone portions in relation to each other. Thereby, the functional cut can allow for comparably precisely repositioning the bone into the target position and any movement therefrom at least in the one degree of freedom can be prevented. Thus, the method according to the invention allows for cutting bone tissue whereas reassembling cut apart portions of the bone tissue in accordance with the intended application is already initially considered. Thereby, it is possible to assure that the bone tissue can be comparably precisely and stably reassembled in the target position without mandatorily requiring additional fixing means or the like. Inaccuracies of manual or similar positioning of the cut apart bone portions while reassembling can be minimized or even excluded.