Pre-cut Trial for Knee Joint Implant Setup
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current surgical instruments for artificial knee joint replacement are cumbersome, require extensive time, and involve complex operations due to the need for precise measurement of tensile forces in both extended and flexed positions, making them laborious and costly, especially when attempting to achieve more than 90° of flexion necessary for Japanese patients.
Innovation Solution
A kit of surgical instruments that includes a pre-cut trial modeled after the genuine femur-side artificial joint, which is mounted before the actual implant to measure the gap and behavior between the femur and tibia in both positions, allowing for accurate adjustment and reduction of operation time by verifying the appropriateness of the implant setup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional bone resection instrument with movable parts and adjustment parts is used to measure tensile forces in extended and flexed positions, then measurement precision is improved, but device complexity increases and operation time increases
Solution Approach 1:
The patent uses a pre-cut trial component that is a simplified copy of the genuine implant, mounted on a pre-cut surface shallower than the genuine cut line. This copy allows observation of extension and flexion behavior without requiring complex measurement instruments, thus achieving measurement precision while reducing device complexity
Solution Approach 2:
The pre-cut trial serves as an intermediary between the bone and the genuine implant. By mounting this intermediate component first, surgeons can observe joint behavior and determine appropriate resection depth before installing the final implant, avoiding the need for complex force measurement devices
2Measurement precision
If a conventional bone resection instrument with many movable parts is used to confirm tensile forces, then measurement accuracy is improved, but ease of operation deteriorates due to laborious adjustments
Solution Approach 1:
The pre-cut trial is a simplified copy that eliminates the need for complex adjustment mechanisms. It can be mounted directly on the pre-cut surface and allows observation of joint behavior without requiring surgical skill for complex adjustments, thus improving ease of operation while maintaining measurement capability
3Measurement precision
If a conventional instrument with extensive adjustment parts is used to measure joint behavior, then measurement precision is improved, but operation time increases
Solution Approach 1:
The pre-cut trial is mounted in advance on a pre-cut surface before the genuine implant installation. This preliminary action allows observation of extension and flexion behavior ahead of time, enabling surgeons to determine appropriate resection depth without time-consuming measurements during the final implantation stage
Solution Approach 2:
The pre-cut trial serves as a temporary copy that can be quickly mounted and removed. It enables rapid assessment of joint behavior through direct observation rather than time-consuming instrument adjustments, thus reducing operation time while maintaining measurement precision
4Manufacturing precision
If accurate resection along a pre-set line is performed without observing joint behavior, then manufacturing precision is improved, but reliability deteriorates when the actual implant is mounted
Solution Approach 1:
The pre-cut trial is mounted in advance on a pre-cut surface to observe joint behavior before final implant installation. This preliminary observation ensures that the resection depth and angle are appropriate for the patient's specific anatomy and movement patterns, guaranteeing reliable implant functionality while maintaining precise resection
Solution Approach 2:
The pre-cut trial acts as an intermediary that bridges the gap between precise pre-set resection lines and actual implant functionality. By allowing observation of joint behavior with this intermediate component, surgeons can verify that the precise resection will result in reliable implant performance
Data Source
Figure 1
Figure 2
Figure 3
AI summary
In a surgical operation for replacing artificial knee joints, before a regular (genuine) implant is mounted as a femur-side member, a resection is performed along a pre-cut line shallower than a genuine-cut line, and a pre-cut trial is mounted; and the extended position and the flexed position and the rotation during flexion are observed, so that it is judged whether the set-up genuine-cut and implant are appropriate. A pre-cut trial is mounted on a pre-cut line which is cut shallower than a genuine-cut line, and the extended and flexed positions of a femur and the state of flexion thereof are observed so as to make judgment whether the genuine implant is appropriate, the pre-cut trial being modeled after the genuine implant which is mounted on resected surfaces formed by genuine-cut performed so as to form the end resected surface, posterior and anterior resected surfaces, and the posterior and anterior chamfer-resected surfaces on the distal end of the femur.