Rotatable Bone Sizing Guide for Accurate Anterior-Posterior Measurement
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Solution Overview
Problem
Existing femoral sizing guides fail to accurately control the effect of rotation on anterior-posterior distance measurement, leading to incorrect selection of femoral implant size and positioning, which can result in misalignment and improper joint function.
Innovation Solution
A bone sizing guide with a rotatable superstructure that adjusts relative to a foot component, allowing independent selection of rotation and size, using a sliding and rotating mechanism to maintain consistent measurement across different rotational positions, and featuring adjustable guide holes for precise alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a femoral sizing guide allows rotational movement between components to enable flexible implant positioning, then the adaptability and flexibility of the device is improved, but the measurement precision deteriorates because the rotation affects the anterior-posterior distance measurement
Solution Approach 1:
The sizing guide employs a dynamic linkage mechanism that allows rotational movement between the body and superstructure components while maintaining a constant measured distance. The linkage dynamically adjusts the geometric relationship between components during rotation, ensuring that the measurement remains accurate regardless of the rotational position of the implant.
Solution Approach 2:
The device changes the geometric parameters of the measurement system in response to rotation. As the superstructure rotates relative to the body, the linkage mechanism modifies the effective measurement parameters to compensate for the rotational displacement, thereby maintaining consistent measurement precision across different implant orientations.
2Measurement precision
If the superstructure is fixed relative to the body, then the measurement precision is maintained, but the adaptability for different rotational positions is reduced
Solution Approach 1:
The linkage mechanism transforms the fixed measurement system into a dynamic one that automatically adapts to different rotational positions. The dynamic geometry of the linkage ensures that the measured distance remains constant even as the superstructure rotates, providing both precision and adaptability.
3Ease of manufacture
If separate instruments are used for resection and sizing, then the functional complexity is reduced, but the device complexity increases due to the need for multiple components and procedures
Solution Approach 1:
The invention merges the resection guide and sizing guide into a single integrated device. The body portion performs resection guidance functions while the superstructure performs sizing measurements, eliminating the need for separate instruments and simplifying the surgical procedure.
Solution Approach 2:
The sizing guide body serves multiple functions: it guides the resection cut and simultaneously provides the measurement superstructure for determining implant size. This multi-functionality reduces the total number of components and procedures required in the surgical workflow.
Data Source
AI summary
A bone sizing guide for assessing the size of an end of a bone includes a body (6) having a foot component (2) with a first surface (10) to rest against an end surface of the bone and a foot (12) extending transverse to the first surface to contact a side surface of the bone. A superstructure (40) is coupled to the body so that the superstructure can slide relative to the body towards and away from the body, at least one of the superstructure and the body being adjustable so that the rotational direction in which the superstructure extends relative to the foot component about a first axis extending transverse to the first surface is adjustable. A stylus (53) extends from the superstructure transverse to the first surface of the body, the stylus having a tip to contact a surface of the bone, and a scale (64) is coupled to or formed on a first one of the superstructure and the body. An indicator (52) is coupled to or formed on a second one of the superstructure and the body to identify a position on the scale. The identified position on the scale shifts as the superstructure slides towards or away from the body, and the identified position shifts as the superstructure rotates relative to the body without sliding motion between the superstructure and the body, such that the identified position on the scale is indicative of the distance between the stylus and the foot.