Unicondylar Knee Implant Bone Resection Guide
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Solution Overview
Problem
Current methods for preparing bone for prosthetic implants, such as unicondylar knee implants, face challenges in minimizing bone removal and ensuring accurate seating surface preparation, particularly in accessing and balancing the knee joint's flexion and extension gaps to maintain joint stability.
Innovation Solution
A method and apparatus utilizing a combination bur template and spacer block, which includes a bur template with a curved surface and a spacer block that can be anchored to the femur and tibia, allowing for precise resection of seating surfaces on both bones while maintaining alignment features for accurate bone removal and gap balancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional methods are used to prepare bone for prosthetic implants, then the implant can be fixed to the bone, but excessive bone must be removed and accuracy in seating surface preparation is compromised
Solution Approach 1:
The patent applies preliminary action by using a guide template to pre-delineate the exact boundary and geometry of the seating surface before bone removal. The guide slot is cut along the peripheral boundary of the intended seating surface, and depth guides are positioned to define the precise depth and contour configuration, ensuring that bone removal is limited exactly to what is necessary and no more.
Solution Approach 2:
The patent replaces traditional mechanical measurement and marking systems with a guide template that integrates geometric constraints directly into the bone preparation process. The template's guide slot and depth guides substitute for manual measurement and calculation, providing automated geometric control that ensures manufacturing precision while minimizing material removal.
2Ease of operation
If access to damaged joints is limited, then the surgical approach is less invasive, but the extent of intrusion required to complete an effective implant increases
Solution Approach 1:
The patent introduces a guide template as an intermediary device that bridges the limitation of surgical access with the requirement for precise seating surface preparation. The template can be positioned through limited access and provides the necessary geometric constraints for accurate bone preparation, acting as a mediator that translates limited access conditions into precise manufacturing outcomes.
3Reliability
If the knee joint is prepared for unicondylar implant, then the implant can replace damaged portions, but it is necessary to remove portions of natural joint beyond merely the damaged portions
Solution Approach 1:
The patent applies preliminary action by pre-defining the exact boundaries of bone removal using the guide template before any actual bone removal occurs. The guide slot follows the peripheral boundary of the seating surface, and depth guides establish the precise depth and contour, ensuring that bone is removed only to the extent necessary for stable implant fixation and no more.
Data Source
AI summary
A method of preparing a knee joint for receiving a unicondylar knee implant includes preparing a first seating surface at a proximal end of a tibia, and providing a combination bur template and spacer block, the bur template having an upper end, a lower end and a curved surface extending between the upper and lower ends thereof that is adapted to conform to a femoral condyle of a femur and the spacer block extending from the lower end of the bur template and having top and bottom surfaces. The method includes flexing the knee joint so that the prepared first seating surface at the proximal end of the tibia opposes a posterior region of the femoral condyle and inserting the combination bur template and spacer block into the knee joint so that the top surface of the spacer block engages the posterior region of the femoral condyle and the bottom surface of the spacer block engages the first seating surface at the proximal end of the tibia. While the spacer block is maintained between the femur and the tibia, the knee joint is extended until the curved surface of the bur template engages the femoral condyle of the femur. The bur template is anchored to the femur and used to guide burring of the femoral condyle for preparing a second seating surface on the femur. After burring the distal end of the femoral condyle, the posterior region of the femoral condyle is resected.