Guided Bone Void Preparation for Offset Knee Prosthesis Stems
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Solution Overview
Problem
Existing methods for preparing bone voids for joint prostheses, such as in total knee replacement revision procedures, often result in inaccurate cavity shapes due to reliance on manual bone removal techniques, leading to issues like undesirable stress distribution and bone regrowth loss, particularly when voids are offset from the intramedullary canal.
Innovation Solution
A surgical system comprising guided instruments, including a support member, offset guide member, and cutting members, allows for precise formation of bone voids offset from the intramedullary canal, using reaming and broaching tools to create accurate cavities that align with metaphyseal reconstruction devices, minimizing the need for freehand bone removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If manual bone removal techniques (freehand burring, rongeur) are used to prepare bone voids, then the procedure can be performed with simple tools, but the cavity shape accuracy deteriorates leading to poor fit with prosthetic components
Solution Approach 1:
The patent introduces a guided reaming instrument as an intermediary tool between the surgeon and the bone void. This instrument includes a guide member that directs cutting elements to precisely shape the bone cavity while offset from the intramedullary canal, achieving accurate cavity geometry without requiring complex freehand techniques
Solution Approach 2:
The instrument performs preliminary guided reaming and broaching actions to prepare the bone void before final prosthesis implantation. The guide member is positioned in advance to establish the correct offset trajectory, allowing systematic bone removal along the predetermined path rather than attempting precise freehand shaping
2Manufacturing precision
If iterative manual bone removal is performed to achieve correct fit, then the cavity can be shaped to receive the prosthesis, but the surgical time increases significantly
Solution Approach 1:
The guide member is positioned and secured in advance to establish the correct offset trajectory from the intramedullary canal. This preliminary positioning allows all subsequent cutting actions to follow the predetermined accurate path, eliminating the need for iterative adjustments and multiple checks against the prosthesis
Solution Approach 2:
The guided instrument serves as a mediator that translates the desired cavity geometry into precise cutting actions. The guide member mechanically constrains the cutting elements to follow the correct trajectory, ensuring accurate cavity shaping in a single pass rather than through repeated iterative removal
3Ease of operation
If reaming is performed only on the intramedullary axis, then the procedure is straightforward, but void areas offset from the IM axis cannot be adequately resected
Solution Approach 1:
The instrument is designed with asymmetric positioning capabilities, allowing the guide member to be offset from the intramedullary canal axis. This asymmetric configuration enables the cutting elements to access and resect bone voids located lateral to the IM canal while maintaining a systematic guided approach rather than requiring complex manual techniques
Data Source
AI summary
A method of implant a knee prosthesis includes forming a bone void at an end of a bone, implanting a void filler in the bone void, and implanting a knee prosthesis onto the end of the bone so that a stem of the knee prosthesis is received by the void filler.