Conical Patellar Resurfacing for Secure Fixation and Bone Preservation
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Solution Overview
Problem
Existing patellar implants face challenges due to simple planar shapes that limit design flexibility, risk detachment, and require extensive bone removal, leading to potential fractures and improper fixation.
Innovation Solution
A conically shaped patellar implant with a porous and solid layer structure, designed to securely attach to resected patella bone, minimizing bone removal and ensuring uniform thickness and improved fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple planar shape is used for the patellar implant, then the manufacturing process is simplified, but the design flexibility and ability to accommodate varying thickness are limited
Solution Approach 1:
The patent applies a conical shape with curved surfaces instead of simple planar shapes. The conical anterior surface with its curved geometry allows for varying thickness distribution while maintaining manufacturability through standardized conical forming processes. This curved geometry enables the implant to accommodate different bone thickness requirements and provides better mechanical fit.
2Device complexity
If the patellar implant uses a simple planar shape, then the structure is simplified, but the risk of detachment from the patellar bone increases
Solution Approach 1:
The conical shape provides superior attachment security through its geometric interlocking with the prepared patellar bone surface. The conical anterior surface engages with the conical resection cavity, creating mechanical retention that prevents detachment. This conical geometry distributes contact forces more effectively across the implant-bone interface compared to planar shapes.
Solution Approach 2:
The patent incorporates a porous coating on the implant surface to enhance biological integration and attachment. The porous structure allows for bone ingrowth and increases the surface area for mechanical interlocking, thereby improving the reliability of attachment to the patellar bone while maintaining the conical geometric design.
3Reliability
If an onlay technique is used to secure the implant, then fixation is achieved, but extensive bone removal is required which may weaken the patella and increase fracture risk
Solution Approach 1:
The conical implant design with its tapered geometry allows for a more conservative bone resection approach. The conical shape enables the implant to achieve adequate fixation with less bone removal compared to planar onlay techniques, as the conical geometry naturally provides mechanical retention through the tapered interface. This reduces the amount of healthy bone that needs to be removed while maintaining fixation reliability.
4Object-affected harmful factors
If an inlay technique is used to secure the implant, then less bone removal is required, but the implant may not be embedded deep enough to provide sufficient fixation
Solution Approach 1:
The conical implant design inherently provides deeper embedding capability while preserving bone. The conical geometry allows the implant to be pressed into the prepared cavity to a greater depth relative to the bone removal volume, achieving better mechanical interlocking. The tapered conical shape creates a friction fit that enhances fixation depth without requiring excessive bone removal, thus balancing bone preservation with adequate embedding depth.
Data Source
AI summary
Disclosed herein are patellar implants and methods to prepare bone for receiving the same. The patellar implant may include an articulating surface and an anterior surface with a non-planar surface to engage with a resected patella. The non-planar surface may include a conically shaped portion to receive the resected patellar bone. A method for resurfacing a patella to implant a patellar implant having a recessed anterior surface may include the steps of determining the minimum implant and resection depth, medial and lateral patellar slope angles to select and resect with a symmetrical reamer.