Arch-Shaped Intercondylar Notch Preparation Apparatus
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Solution Overview
Problem
Current methods for preparing the intercondylar area of a patient's femur for knee prosthesis surgery often result in structural weaknesses, excessive bone removal, and potential fractures due to sharp corners and high stress concentrations, with existing techniques failing to create an arch-shaped notch and effectively collect discrete bone for reuse.
Innovation Solution
An apparatus comprising a guide and a hole saw with a bore oriented at an acute angle to create an arch-shaped intercondylar notch, allowing for minimal bone removal and collection of discrete bone pieces, which can be reused during surgery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a sagittal saw is used to form three resections at right angles to each other, then the intercondylar region can be prepared with box-shaped geometry, but sharp square corners are created leading to concentrated bone stresses and significant possibility of femoral fracture
Solution Approach 1:
The invention replaces the traditional box-shaped resection with sharp corners with a rounded, arch-shaped intercondylar region. The cutting guide directs the saw to create curved transitions instead of sharp angles, eliminating stress concentration points while maintaining adequate bone removal for prosthesis placement. This curvature principle directly addresses the fracture risk associated with sharp corners.
2Productivity
If a punch is used to remove intercondylar bone with a notch preparation guide, then the shape of the box can be better controlled and it takes less time, but the punch may result in small or large cracks in the remaining bone of the distal femur
Solution Approach 1:
The invention replaces the punch mechanism with a controlled saw cutting system guided by a cutting guide. Instead of using impact forces that can cause cracks, the saw systematically removes bone through controlled cutting planes. The cutting guide ensures precise geometry while the saw's gradual removal process avoids the sudden stress concentrations that cause cracking.
3Manufacturing precision
If a milling device is used to remove bone from the intercondylar notch, then some improvement in notch preparation is achieved, but the milling device creates a dust that is relatively useless and cannot be collected for other purposes
Solution Approach 1:
The invention uses a cutting guide with multiple cutting surfaces that create discrete, structured bone segments rather than dust. The guide directs the saw to make specific cutting planes that result in separable bone portions, including a removable triangular section. This segmented approach maintains precision while preserving bone material in collectible forms.
4Ease of operation
If excessive bone is removed from the intercondylar area, then clearance is provided for the cam and post of the prosthetic system, but the integrity of the modified structures of the femur is compromised and patient recovery is compromised
Solution Approach 1:
The cutting guide is designed with specific localized cutting surfaces that remove bone only where needed for prosthesis clearance. The guide includes a first cutting surface for the anterior aspect, a second cutting surface for the posterior aspect, and a third cutting surface for the intercondylar region. This localized approach provides necessary clearance for the cam and post while preserving bone integrity in critical load-bearing areas.
Data Source
Figure 1
Figure 2A~2B
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AI summary
Methods and apparatus provide for modifying an intercondylar notch of a patient's femur, including cutting bone from the intercondylar notch using a hole saw having a hollow cylinder and a circular cutting edge, where the hollow cylinder of the hole saw defines a central longitudinal axis which is oriented with reference to the patient's femur such that the circular cutting edge of the hole saw removes a portion of material from the intercondylar notch of the patient's femur.