Asymmetric Surgical Post Rotational Extraction Mechanism
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Solution Overview
Problem
The removal of surgical posts, such as perineal posts, from a surgical table is challenging due to their confined space location under the sterile field and resistance from patient tissue, requiring parallel motion that is difficult to manage during procedures like fracture repair and hip surgery.
Innovation Solution
A surgical assembly with a post and platform design that allows for easy removal by translating a sleeve along the post, enabling the post to change dimensions to fit through a narrow opening, and utilizing a locator and spring mechanism to secure and release the post, allowing rotation for clearance without longitudinal translation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the post is removed by moving it parallel to its axis, then the post can be detached from the support, but the patient's groin and thigh tissue resist this motion making removal difficult
Solution Approach 1:
The patent changes the removal motion from longitudinal (parallel to axis) to rotational (perpendicular to axis). The post is designed to rotate within the opening rather than being pulled straight out, utilizing a different dimensional approach to overcome tissue resistance. The asymmetric cross-section of the post enables this rotational extraction path.
Solution Approach 2:
Instead of removing the post by pulling it outward along its axis (conventional approach), the invention inverts the removal mechanism by rotating the post within the opening. The post's asymmetric geometry allows it to be extracted through rotational motion in the opposite direction of conventional linear removal, effectively bypassing the resistant tissue path.
2Reliability
If the post is designed with a fixed dimension larger than the throat, then the post remains secure during surgery, but the post cannot be removed through the opening
Solution Approach 1:
The post transitions from a static fixed-dimension design to a dynamic asymmetric design. The post has different cross-sectional dimensions at different orientations, allowing it to be inserted in one orientation (secure fit) and removed by rotating to a different orientation (clearance fit). This dynamic geometric transformation enables both secure retention and easy removal.
Solution Approach 2:
The post features an asymmetric cross-section with different dimensions along perpendicular axes. This asymmetry allows the post to be inserted with its larger dimension perpendicular to the throat (secure fit during surgery) and removed by rotating 90 degrees so the smaller dimension aligns with the throat opening (easy removal). The asymmetric geometry resolves the contradiction between security and removability.
3Reliability
If the opening has a narrow throat, then the post fits securely during surgery, but the post is difficult to remove without longitudinal movement
Solution Approach 1:
The post's asymmetric cross-section is the key feature that simplifies the removal mechanism. By designing the post with different dimensions along perpendicular axes, the narrow throat provides secure retention during surgery while allowing rotational removal. This asymmetric design eliminates the need for complex longitudinal movement mechanisms, actually reducing device complexity.
Data Source
AI summary
A surgical assembly (20) comprises a post (100) having a longitudinally extending axis (104), a support (56) for resisting movement of the post in a negative longitudinal direction, and a platform (70) offset from the support in a positive longitudinal direction. The platform includes an opening (82) through which the post projects. The opening includes a throat (86). The post has a first dimension which renders the post incapable of passing through the throat and a second dimension which renders the post capable of passing through the throat. Alternate embodiments in which the post can be removably engaged with the support and platform and disengaged therefrom without translating the post in the longitudinal direction are also disclosed.