Bone Surface Preparation for Cementless Implant Fixation
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Solution Overview
Problem
Traditional bone preparation methods in knee arthroplasty surgeries result in surfaces of variable accuracy, which can compromise the initial fixation of cementless implants, leading to micromotion, fibrous ingrowth, and bone resorption, affecting the long-term success of bone ingrowth/ongrowth onto the implant.
Innovation Solution
The method involves preparing bone surfaces with designed areas having accurate tolerance profiles, including resecting bone surfaces to create regions with specific cross-sectional densities and applying retention elements and downward force to compact bone, ensuring stable initial fixation and promoting long-term bone ingrowth/ongrowth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manual instrumentation is used to prepare bone surfaces, then the surgical procedure is simple and quick, but the bone surface accuracy is variable and insufficient for reliable implant fixation
Solution Approach 1:
The bone surface is divided into multiple zones with different tolerance requirements. The robotic system prepares different regions of the bone surface to different levels of accuracy, with the implant contact zone receiving the highest precision preparation while other areas have progressively relaxed tolerances. This segmentation allows high accuracy where needed without requiring uniform high precision across the entire bone surface, thereby managing overall system complexity.
Solution Approach 2:
Different regions of the bone surface are prepared with different quality levels corresponding to their functional requirements. The implant contact zone is prepared to tight tolerances for stable fixation, while non-contact areas have relaxed tolerances. This local differentiation of quality enables reliable implant fixation without the need for uniformly high precision across all bone surfaces, reducing overall preparation complexity.
2Reliability
If uniform high accuracy is applied to the entire bone surface, then implant fixation is improved, but the preparation time and complexity increase significantly
Solution Approach 1:
The bone surface preparation is segmented into zones of varying tolerance requirements. Only the critical implant contact zone receives high-precision preparation, while other areas are prepared to relaxed tolerances. This selective approach ensures reliable implant fixation without applying uniform high accuracy across the entire bone surface, thereby reducing preparation time.
Solution Approach 2:
High-precision preparation is applied partially only to the specific region where the implant contacts the bone, rather than excessively preparing the entire bone surface. This partial action approach achieves the necessary fixation stability while minimizing unnecessary preparation time spent on non-critical areas.
3Productivity
If the bone surface is prepared with relaxed tolerances, then the preparation process is faster and simpler, but micromotion occurs leading to fibrous ingrowth and bone resorption
Solution Approach 1:
The bone surface is prepared with different quality levels in different regions. The implant contact zone receives high-precision preparation to eliminate micromotion and prevent fibrous ingrowth, while non-contact areas have relaxed tolerances for efficient preparation. This local quality differentiation prevents harmful micromotion effects at the critical interface while maintaining overall preparation efficiency.
Solution Approach 2:
The tolerance parameter of bone surface preparation is changed based on location. Tight tolerances are applied to the implant contact zone to prevent micromotion and bone resorption, while relaxed tolerances are used in other areas to maintain preparation efficiency. This parameter change strategy eliminates harmful effects where they matter most without sacrificing overall productivity.
Data Source
AI summary
Disclosed herein are systems and methods for bone preparation with designed areas having accurate tolerance profiles to enable improved initial fixation and stability for cementless implants and to improve long-term bone ingrowth/ongrowth to an implant. One method includes preparing a bone surface to receive a prosthetic implant thereon by resecting the bone surface using a first cutting path to create a first resected region and resecting the bone of the patient using a second cutting path to create a second resected region at least partially overlapping the first resection region. The second cutting path is different than the first cutting path and either manual or robotic cutting tools can be used for creating the first and second resected regions.