Disposable Reamer Shaft Centerline Alignment
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Solution Overview
Problem
Existing surgical reamers used in orthopedic procedures, particularly for hip and shoulder replacements, face issues with dull cutting edges after single use, leading to inefficient bone cutting, heat generation, and potential bone damage due to friction, along with alignment problems causing wobble during rotation, which affects the precision and safety of bone cavity preparation.
Innovation Solution
A modular disposable reamer shaft system with precise concentric attachment to a reusable shaft, utilizing small-diameter, long-length rods or tubes with epoxy-glued attachment pieces for secure alignment, and optionally cannulated or flexible designs made from stainless steel or fiber-reinforced polymers, ensuring wobble-free rotation and efficient bone cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solid spherical reamers are used for multiple surgeries, then the initial cutting efficiency is high, but the cutting edges dull quickly causing friction heat generation and bone damage
Solution Approach 1:
The patent implements a disposable hollow reamer system where the entire reamer assembly including cutting elements is discarded after a single use. This eliminates the dulling problem entirely by ensuring every reamer has sharp cutting edges, preventing friction heat generation and bone damage while maintaining consistent cutting efficiency throughout its service life.
Solution Approach 2:
The hollow reamer design allows for collection of bone debris through the hollow shaft during the reaming process. The bone debris is captured and removed from the surgical site, preventing it from being incorporated into the bone tissue or causing interference with the surgical procedure, thereby improving the overall surgical outcome.
2Ease of manufacture
If reusable reamers are used across multiple patients, then equipment cost is reduced, but contamination risk and bone debris incorporation increase
Solution Approach 1:
The patent employs a disposable hollow reamer that is discarded after single use, completely eliminating cross-contamination risks between patients and preventing bone debris from being incorporated into the bone tissue. The disposable nature ensures sterility and prevents bone healing problems while maintaining cost-effectiveness through the hollow design that enables bone debris collection.
3Device complexity
If non-concentric attachment methods are used between shaft and cutting bowl, then assembly is simpler, but wobble occurs during rotation affecting precision
Solution Approach 1:
The patent integrates the cutting bowl and shaft into a unified concentric assembly where the cutting bowl is precisely mounted on the shaft's central axis. This merging of components with built-in concentricity ensures wobble-free rotation and high cutting precision while maintaining assembly simplicity through the integrated design.
4Strength
If solid shaft reamers are used, then structural strength is high, but heat dissipation and bone debris removal efficiency are reduced
Solution Approach 1:
The patent utilizes a hollow shaft configuration that functions similarly to porous structures by providing internal channels for bone debris removal and heat dissipation. The hollow interior allows efficient evacuation of bone debris during reaming while enabling thermal management, maintaining structural strength through optimized wall thickness and material selection.
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 provides a cost-effective, low-cost, and contamination-free disposable reamer shaft that maintains precise alignment and cutting efficiency throughout multiple surgeries, minimizing heat generation and ensuring accurate bone preparation without compromising the integrity of surrounding tissue.
Implementation Method 1
one end of said rod or tube stock glued with epoxy or other suitable glue to a hollow reamer attachment piece
Data Source
AI summary
A low cost disposable reamer shaft is made from a rod or tube stock of stainless steel, Nitinol or fiber reinforced polymer having a precise outer diameter in the range of 4 to 14 millimeter and is cut to a shaft length of 250 to 400 millimeters. An attachment piece with male or female thread matching a spherical hollow or tapered hollow reamer is machined and glued with epoxy on one end of the rod of tube stock using a precision centerline aligning jig. An attachment piece for connecting to a drive power unit is machined and glued with epoxy to the other end of the rod or tube stock thus forming a low cost disposable reamer shaft that aligns the centerline of the shaft with that of the reamer. The shaft contacts the reamer at two attachment locations that are displaced from each other, providing precise centerline alignment.