Distal Radioulnar Joint Prosthesis with Stabilizing Surfaces
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Solution Overview
Problem
Current treatments for the distal radioulnar joint, particularly affected by rheumatoid arthritis, often result in instability and pain due to cartilage destruction and ligament compromise, with existing solutions compromising wrist and hand functions for pain relief.
Innovation Solution
A prosthetic implant with a double-curved articular surface and stabilizing surfaces, designed to fit within the ulna's medullary canal, allowing adjustment of ligament tension through selection of appropriate head and stem sizes, preserving the ulnar carpal ligaments and triangular fibrocartilaginous complex for stable joint replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the ulnar head is resected (Darrach procedure), then pain is relieved, but joint instability and clicking sensations occur
Solution Approach 1:
The prosthesis extracts only the damaged articular surface of the ulnar head while preserving the majority of the ulnar head structure and its ligamentous attachments. This selective removal relieves pain from cartilage destruction while maintaining joint stability through preserved soft tissue structures.
Solution Approach 2:
The prosthesis acts as an intermediary component that replaces the damaged articular surface while maintaining the natural ligamentous attachments. The implant mediates between the damaged bone surface and the preserved soft tissue structures, allowing pain relief without sacrificing joint stability.
2Stability of the object's composition
If ligaments are detached for joint replacement, then joint instability is corrected, but wrist and hand functions are compromised
Solution Approach 1:
The prosthesis applies local quality by replacing only the damaged articular surface at the distal ulna while preserving the ligamentous attachments and their insertion sites. This localized intervention maintains joint stability where needed without compromising the functional attachments of the ligaments to the wrist and hand.
Solution Approach 2:
The procedure uses partial action by replacing only the necessary articular surface rather than performing complete joint replacement. This partial replacement achieves joint stability while preserving the ligamentous structures that maintain wrist and hand function.
3Stability of the object's composition
If complete ulnar head replacement is performed, then joint stability is improved, but soft tissue structures are compromised
Solution Approach 1:
The prosthesis extracts only the damaged portion of the ulnar head articular surface while leaving the majority of the ulnar head and its soft tissue attachments intact. This selective extraction avoids loss of soft tissue structures while still achieving joint stability.
Solution Approach 2:
The procedure employs partial action by replacing only the necessary articular surface rather than the entire ulnar head. This partial replacement maintains joint stability while preserving soft tissue structures that would be lost in complete replacement.
Data Source
AI summary
A prosthetic implant for partial resurfacing of the ulna at the distal radioulnar (DRU) joint which comprises a stem and an ulnar head. The combination of the anchoring stem and the head that is shaped and proportioned to replace only a portion of the distal ulnar head and the radial articulating surface and to interface with the resected ulna at a proximal stabilizing surface provides excellent stability in the completed implant. In the preferred embodiment, a pair of strategically located surfaces aligned at an obtuse angle provides the stabilizing surface arrangement. The provision of a set of such implants with different head and stem sizes allows a surgeon to best accommodate the physiology of a particular patient and locate a resurfaced head section offset from the canal center in order to provide a convex articular surface adjacent the radius which will allow the radius to smoothly pivot and translate around such resurfaced ulnar head during pivoting of the forearm.