Distal Radioulnar Joint Prosthesis for Ulna Resection
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Solution Overview
Problem
Existing distal radioulnar joint prostheses fail to preserve the triangular fibrocartilaginous complex (TFC) and maintain normal joint stability after resection of the ulna, leading to instability and loss of freedom of movement in the forearm.
Innovation Solution
A distal radioulnar joint prosthesis comprising a first prosthesis member fixed to the ulna and a second prosthesis member that extends into the space created by resection, allowing pivot and rotational movement, thereby preserving the TFC and maintaining the freedom of movement between the ulna and radius.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the distal end portion of the ulna is resected to improve freedom of movement, then the joint stability deteriorates and the TFC is lost
Solution Approach 1:
The prosthesis is divided into two separate members: a first prosthesis member that articulates with the radius and a second prosthesis member that attaches to the proximal ulna. This segmentation allows the distal radioulnar joint to maintain freedom of movement while the proximal attachment provides joint stability and preserves the TFC functional integrity.
Solution Approach 2:
The first prosthesis member acts as an intermediary between the radius and the second prosthesis member on the ulna. It provides the articulating surface that replaces the resected distal ulna, enabling movement while maintaining stable connection to the radius, thus preserving TFC function without requiring its resection.
2Volume of moving object
If the distal end portion of the ulna is resected to create space for prosthesis, then the TFC is removed and load transmission is compromised
Solution Approach 1:
The first prosthesis member creates an artificial articulating surface that copies the functional role of the distal ulna head. It provides a spherical or domed surface that articulates with the radius in a manner similar to the natural ulnar head, thereby maintaining load transmission pathways and TFC function without the actual TFC tissue.
Data Source
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AI summary
A prosthesis (1) for reconstruction of a distal radioulnar joint after resection of a part of the ulna close to a distal end portion (U1) thereof, comprises a first prosthesis member (2), fixation means (3) and a second prosthesis member (4). The first prosthesis member (2) is configured for fixation to the distal end portion (U1) of the ulna. The fixation means (3) are configured to extend into the radius via said distal end portion of the ulna for locking said distal end portion of the ulna to the radius. The second prosthesis member (4) is configured for fixation to the ulna (U2) proximally of a space (US) which is defined between the distal end portion (U1 ) of the ulna and the ulna proximally of said space by the resection of said part of the ulna close to said distal end portion of the ulna. The second prosthesis member (4) is also configured to extend into said space (US) for being joined with the first prosthesis member (2) in a manner which allows said first and second prosthesis members to at least pivot and rotate relative to each other. Said prosthesis may be used also for reconstruction of a proximal radioulnar joint.