Version Protractor with Pendulum for Hip Femur Angle Measurement
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Solution Overview
Problem
During hip replacement procedures, accurately determining the version angle of the restored femur neck is crucial to prevent misalignment between the femoral prosthetic and the acetabulum, which can lead to complications such as increased wear and tear and unbalanced tension in surrounding ligaments.
Innovation Solution
An apparatus comprising a broach with a distal end insertable into the femur's medullary canal and a protractor with a rod attachable to the broach's proximal end, allowing for measurement of the version angle relative to a vertical direction, is used. The method involves inserting the broach, flexing the knee, orienting the tibia vertically, and attaching the protractor to measure the version angle, potentially using a pendulum, bubble level, or electronic inclinometer for accurate readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a protractor with pendulum is used to measure version angle, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The pendulum automatically aligns with the vertical direction under gravity, eliminating the need for external alignment tools or procedures. The weight at the lower end of the rod ensures the protractor self-calibrates to the vertical reference, providing accurate version angle measurement without additional complex alignment mechanisms.
Solution Approach 2:
The rod acts as an intermediary element that connects the broach (inserted into the medullary canal) to the vertical reference established by the pendulum. This intermediate structure allows the transfer of orientation information from the anatomical reference frame to the measurement scale, enabling accurate version angle determination.
2Ease of operation
If the protractor rod is made longer to extend further from the neck axis, then measurement accessibility is improved, but device dimensions increase
Solution Approach 1:
The protractor is divided into distinct functional segments: the rod for positioning and extending from the broach, the pendulum for establishing vertical reference, and the scale for measurement. This segmentation allows each component to be optimized independently - the rod can be sufficiently long for accessibility without unnecessarily increasing overall device size, as other components are compact.
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 approach enables precise measurement of the version angle, allowing for appropriate alignment of the femoral prosthetic and acetabular cup, reducing the risk of complications and enabling adjustments or selection of suitable implants to ensure correct operation of the hip joint.
Implementation Method 1
The protractor may include a pendulum pivotably mounted on the rod to hang vertically for measuring the version angle relative to the vertical direction
Implementation Method 2
The protractor may include a bubble level attached to the rod
Data Source
AI summary
An apparatus and method for measuring a version angle of a restored neck of a femur during a hip replacement procedure. The apparatus includes a broach. The broach has a distal end that is insertable into a medullary canal of the neck of the femur. The broach also has a proximal end that extends along a neck axis of the broach. The apparatus also includes a protractor. The protractor includes a rod which is attachable to the proximal end of the broach to extend away from the neck axis of the broach for measuring the version angle of the restored neck of the femur relative to a vertical direction. The method includes inserting the broach, flexing the knee at approximately ninety degrees, orienting the tibia vertically, attaching the protractor to the proximal end of the broach and using it to measure the version angle.