Femoral Drill Guide with Cam Mechanism for Knee Arthroplasty
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Solution Overview
Problem
There is a need for an apparatus and method to prepare the knee joint for a unicondylar knee system that preserves as much of the natural bone surfaces as possible during resection of the tibial and femoral articulating surfaces, while ensuring accurate alignment and spacing for the implant.
Innovation Solution
The use of a femoral drill guide with a cam and cam follower mechanism, along with a tibial and femoral spoon system, allows for precise translation and adjustment of cutting surfaces to widen the joint space, enabling the preparation of femoral and tibial surfaces for a partial knee prosthesis with minimal disturbance to natural bone, using an intramedullary rod link assembly for alignment and a tibial cut guide for accurate cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional resection methods are used to prepare tibial and femoral surfaces for unicompartmental knee replacement, then the implant can be installed, but excessive natural bone surface is removed
Solution Approach 1:
The drill guide is positioned and engaged with the femur and tibia before any resection occurs. The engagement members (spoons) are initially positioned to contact the bone surfaces, establishing reference points and planned resection depths before cutting begins, thereby preventing excessive bone removal
Solution Approach 2:
The drill guide acts as an intermediary device between the surgeon and the bone surfaces. It includes engagement members (femoral and tibial spoons) that contact and reference the natural bone surfaces, and cutting surfaces that guide resection depth, mediating the interaction to preserve bone while achieving implant preparation
2Manufacturing precision
If the joint space is widened to accommodate the prosthesis, then proper implant spacing is achieved, but the complexity of the apparatus increases
Solution Approach 1:
The drill guide incorporates adjustable engagement members that can be positioned and locked at different depths and locations on the bone surfaces. The adjuster mechanism allows dynamic adjustment of the spoons' positions to accommodate varying patient anatomy and achieve the desired joint space widening while maintaining apparatus manageability
Solution Approach 2:
The drill guide is divided into separate functional components: a body portion, adjustable engagement members (spoons), cutting surfaces, and an adjuster mechanism. This segmentation allows each component to perform its specific function independently while being assembled into a complete apparatus, managing complexity through modularity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for precise and conservative preparation of the knee joint surfaces, ensuring proper alignment and spacing for the implant, thereby preserving natural bone and facilitating a successful unicondylar knee replacement with improved joint space management.
Implementation Method 1
A cam and cam follower associated with the femoral drill guide can be operable to communicate rotation of the dial member into translation of at least one of the first and second engagement members
Implementation Method 2
The tibial cut guide can be magnetically coupled to the femoral cut guide
Data Source
AI summary
A set of instruments for preparing a femur and tibia for receipt of a partial knee prosthesis can include a femoral drill guide that is selectively connected to an intramedullary (IM) rod. At least one sizing spoon can communicate with the femoral drill guide. The femoral drill guide can have terminal cutting surfaces. A tibial cut guide can be selectively connected to the femoral drill guide. A dial member can be disposed on one of the femoral or tibial cut guides that when rotated moves at least one of the spoons in a superior/inferior direction.