Knee Implant Fins and Visualization Contradiction
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Solution Overview
Problem
Existing orthopaedic implants, such as tibial trays, face challenges in visualization during imaging due to fins or keels, difficulty in removal or revision, and instability, particularly in uneven bone distribution, leading to potential subsidence or migration.
Innovation Solution
Designs featuring a finned platform, tibial trials with fins for bone reinforcement, modular stems with fluting for improved fixation, and instruments like reamers and fixation pegs with openings for enhanced visualization and easy removal, along with rasp features for surface preparation, address these issues by reducing stiffness while maintaining strength, facilitating visualization, and enhancing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fins or keels are added to the implant to increase strength and prevent rotation, then the implant's rigidity and rotational stability are improved, but the visualization of the implant and surrounding anatomy using x-ray is impaired
Solution Approach 1:
The patent removes the fin or keel structure from the implant design. By extracting this obstructive element, the implant maintains its primary function while eliminating the interference with x-ray imaging, allowing clear visualization of the implant and surrounding bony anatomy without the blocking effect of protruding fins or keels
Solution Approach 2:
The patent employs a porous coating on the implant surface that provides structural integrity and rotational stability while being radiolucent. This porous structure allows x-rays to pass through, enabling clear imaging of the implant-bone interface and surrounding anatomy without requiring dense solid fins or keels for fixation
2Stability of the object's composition
If a fin or keel structure is used to prevent rotation, then the implant's resistance to rotation is improved, but the access to certain areas of the bone-implant interface is impeded
Solution Approach 1:
The patent eliminates the fin or keel structure that physically blocked surgical access. By removing this obstructive component, surgeons gain unimpeded access to all areas of the bone-implant interface for inspection, cleaning, and revision procedures, while rotational stability is achieved through alternative means such as porous coating and precise fit
Solution Approach 2:
The patent replaces the mechanical fin/keel system with a surface-level fixation mechanism using porous coating and precise dimensional fit. This substitution maintains rotational stability through surface engagement and bone ingrowth rather than through protruding mechanical structures that block access
3Strength
If the implant is designed with a keel structure, then the strength and fixation are improved, but the removal or revision becomes difficult
Solution Approach 1:
The patent removes the keel structure that created removal difficulties. By extracting this permanent-looking component, the implant becomes easily removable through standard surgical techniques, while initial fixation strength is achieved through porous coating and precise fit that allow for controlled revision when needed
Solution Approach 2:
The patent designs the implant with a focus on recoverability and revisability. The implant can be easily removed and replaced if necessary, with the porous coating allowing for controlled integration that doesn't permanently anchor the device, enabling future revisions without excessive bone removal
4Strength
If the implant stiffness is increased to maintain structural integrity, then the strength is improved, but the flexibility to conform to uneven resected surfaces is reduced
Solution Approach 1:
The patent applies different properties to different parts of the implant. The overall structure maintains sufficient stiffness for structural integrity, while the surface layer features porous coating with varying porosity and compliance to allow conformability to uneven resected surfaces. This local differentiation enables both strength and adaptability
Data Source
AI summary
There are provided various embodiments of medical instruments to perform knee surgery. In one embodiment a finned platform for mounting a cutting block is provided. The finned platform can be used on either a femur or tibia to allow for the proper cuts when performing a knee surgery. In another embodiment, a tibial trial is shown having a fin. The fin is useful to reinforce the bone to reduce the risk of fracture during bone preparation. In another embodiment, a reamer is provided having a plurality of cutting flutes. It may be desirable to utilize a guide with the reamer to allow the reamer to cut a non-circular portion of the tibial bone. In yet another embodiment, a plurality of fixation pegs are provided on the tibial implant to allow for easy removal of such implant if a revision surgery becomes necessary.