Disposable Plastic Bone Removal Instrument with Temperature-Sensitive Metal Insert
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Solution Overview
Problem
Current bone removal instruments for hip and knee prosthetic surgery, such as rasps and cutting units, are expensive to produce and pose a risk of infection due to potential reuse, necessitating a cost-effective and single-use solution.
Innovation Solution
Manufacturing these instruments primarily in plastic materials with specific hardness and temperature degradation properties, ensuring they deteriorate after a single use, eliminating the need for re-sterilization and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal materials are used for bone removal instruments, then wear resistance and hardness are sufficient to attack bone, but production cost increases and reuse creates infection risk
Solution Approach 1:
The patent applies the disposable principle by designing bone removal instruments made of plastic that are intended for single-use only. The instruments are discarded after one use, eliminating the need for expensive metal materials and complex sterilization processes, while still providing sufficient hardness for bone removal during the single operation.
Solution Approach 2:
The patent changes the material parameter from metal to plastic, specifically selecting plastic with hardness between 5-30% higher than bone hardness. This parameter change enables the instrument to effectively remove bone while being inexpensive enough for single-use disposal, resolving the contradiction between hardness requirements and production cost.
2Duration of action of stationary object
If metal ancillaries are re-sterilized in autoclave, then they can be reused, but the metal inserts come away from the body and the ancillary can no longer be used
Solution Approach 1:
The patent resolves this contradiction by making the ancillary disposable rather than reusable. The plastic construction with embedded metal inserts is designed for single-use, eliminating the structural integrity problem that occurs during autoclave sterilization while avoiding the need for repeated sterilization cycles.
Solution Approach 2:
The patent uses composite materials consisting of plastic with embedded metal inserts. This composite structure provides the necessary hardness for bone removal while the plastic matrix holds the metal inserts in place during single use, and the entire assembly is discarded after one operation, avoiding sterilization-induced structural failure.
3Ease of manufacture
If plastic material is used for bone removal instruments, then manufacturing cost decreases and single-use is enabled, but hardness may be insufficient to attack bone
Solution Approach 1:
The patent changes the hardness parameter of the plastic material to be between 5-30% higher than bone hardness. This specific parameter range ensures the plastic is soft enough to be inexpensive and manufacturable, yet hard enough to effectively remove bone during the single operation.
Solution Approach 2:
The patent employs composite materials by embedding metal inserts within the plastic structure. The metal inserts provide localized hardness for effective bone removal at the contact points, while the plastic body maintains low cost and enables disposable construction.
4Reliability
If plastic ancillary is sterilized by autoclave, then re-sterilization is possible, but the plastic deteriorates due to free radicals and the ancillary cannot be reused
Solution Approach 1:
The patent resolves this contradiction by designing the ancillary for single-use disposal rather than re-sterilization. The initial sterilization is performed by gamma or beta radiation, and the ancillary is discarded after one use, avoiding the free radical degradation that occurs during autoclave sterilization of plastic.
Solution Approach 2:
The patent changes the sterilization method parameter from autoclave (thermal) to radiation (gamma or beta). This parameter change enables effective sterilization without generating free radicals that would deteriorate the plastic, while the single-use design ensures the sterilized ancillary is not subjected to repeated sterilization cycles.
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 use of plastic materials with controlled hardness and temperature-dependent degradation ensures single-use instruments, reducing production costs and minimizing infection risks while maintaining effectiveness for bone removal.
Implementation Method 1
the plastic is chosen so that it deteriorates at or above a Ti temperature between 50° C. and 200° C., preferably between 70° C. and 150° C., specifically at or above a temperature equal to 137° C.
Implementation Method 2
When the ancillary is thus heated in an autoclave for example, to try and 're-sterilise' it at a Ti temperature of 137° for example, the metal inserts irreversibly come away from the body and the ancillary can no longer be used.
Data Source
AI summary
The invention concerns an accessory for removing material, in particular a file (3) or a cutting block, for prosthesis implantation surgery, in particular for hip or knee prostheses. The invention is characterised in that it comprises at least partly one plastic part and at least one insert (4, 10, 5) made of a material harder than the bone material, in particular of metal, which is fixed to the plastic material such that if the device is brought to a temperature Ti, the insert is separated from the plastic material.