Intramedullary Alignment Apparatus with Nested Tube Clamp
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Solution Overview
Problem
Existing alignment apparatuses for guiding cutting elements in intramedullary canals during hip replacement surgery are bulky and lack precision, risking perforation of the femur bone during cement removal, which can compromise the fixation of new prostheses.
Innovation Solution
An alignment apparatus featuring a coaxial inner and outer tube frame with a clamp assembly that includes movable rings connected by flexible legs, allowing for secure and accurate clamping within the intramedullary canal, minimizing the risk of perforation and ensuring precise positioning of the cutting element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a frame with clamp assembly is used to guide the cutting element, then positioning accuracy is improved, but the device becomes bulky and complex
Solution Approach 1:
The alignment apparatus employs a nested tube structure where an inner tube is positioned within an outer tube. The clamp assembly is mounted on the inner tube, which can slide relative to the outer tube. This nesting arrangement provides a compact, space-efficient design that maintains positioning accuracy while reducing overall device complexity and bulkiness.
Solution Approach 2:
The device is segmented into distinct functional modules: the outer tube provides structural support and insertion guidance, the inner tube carries the clamp assembly and can be independently positioned, and the clamp assembly itself is a separate adjustable component. This segmentation allows each part to perform its specific function efficiently while keeping the overall design manageable and less complex.
2Reliability
If the clamp assembly is positioned within the intramedullary canal close to the cement, then cutting element positioning is more reliable, but the risk of perforating the bone increases
Solution Approach 1:
The clamp assembly features adjustable spreading members with clamping surfaces that can be locally adapted to engage specific regions of the intramedullary canal. The spreading members can be adjusted to distribute clamping forces locally on the canal walls rather than concentrating force at single points, providing reliable positioning while minimizing the risk of bone perforation through localized, controlled engagement.
Solution Approach 2:
The clamp assembly is designed with movable spreading members that can dynamically adjust their position and orientation in response to the specific geometry of the intramedullary canal. This dynamic adjustment capability allows the clamp to achieve reliable cutting element positioning while adapting to varying canal conditions, thereby reducing the risk of perforation through flexible, rather than rigid, engagement.
3Measurement precision
If the frame is inserted into the intramedullary canal, then alignment precision is improved, but the device dimensions become constrained
Solution Approach 1:
The alignment apparatus employs a nested tube structure where an inner tube is positioned within an outer tube. The clamp assembly is mounted on the inner tube, which can slide relative to the outer tube. This nesting arrangement provides a compact, space-efficient design that maintains positioning accuracy while reducing overall device complexity and bulkiness.
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
The apparatus provides a secure, accurate, and reliable method for removing cement from the femur bone without risking perforation, ensuring stable positioning of the cutting element and facilitating easy operation with a compact design.
Implementation Method 1
relative motion of the two rings of the first spreader causes flexing of the flexible legs, such that an approaching motion of the two rings of the first spreader causes the flexible legs to flex out and engage the intramedullary canal
Data Source
Figure 1~2
Figure 3~4
AI summary
An alignment apparatus (1) for guiding a cutting element along a predetermined path in an intramedullary canal of a human bone, said apparatus comprising: -a frame (2) for guiding the cutting element along the predetermined path; -an adjustable clamp assembly (5), connected to said frame (2), for clamping the frame (2) to the bone;wherein: -the frame (2) comprises at least one tube (3, 4) with a lumen for guiding the cutting element, and which frame (2) is arranged to be inserted into the said intramedullary canal; and -the clamp assembly (5) is provided at a distal end (6) of the at least one tube (3, 4); -the frame (2) comprises an inner tube (3) and an outer tube (4) that are coaxially positioned with respect to each other; which inner tube (3) and outer tube (4) are arranged to be inserted into said intramedullary canal; -the inner tube (3) is provided with the lumen for guiding the cutting element; -the clamp assembly (5) is configured to be actuable for clamping to the bone by a relative motion of the inner tube (3) and outer tube (4) with respect to each other;characterized in that -the clamp assembly (5) is provided on the inner tube (3) and comprises at least a first spreader (7, 8) which is embodied with two rings (9, 10; 11, 12) distant from each other that are mounted on and movable along the inner tube (3), and that are connected to each other with flexible legs (13, 14); -a first stop (15) is provided at a distal end (6) of the inner tube (3) to prevent that the first spreader (7, 8) slides off the inner tube (3); -a second stop (16) is embodied by a distal end (17) of the outer tube (4) which limits movement of at least one (12) of the two rings of the first spreader (7, 8); -relative motion of the two rings (9, 10; 11, 12) of the first spreader (7, 8) causes flexing of the flexible legs (13, 14), such that an approaching motion of the two rings (9, 10; 11, 12) of the first spreader (7, 8) causes the flexible legs (13, 14) to flex out and engage the intramedullary canal so as to act as a clamp within said intramedullary canal.