Telescopic Intramedullary Nail Non-Circular Extraction
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Solution Overview
Problem
Existing telescopic intramedullary nails, such as the Fassier-Duval nail, face challenges including difficulty in extracting the rod component during removal, potential seizure issues due to local deformation of the rod, and complexity in selecting the correct size of the hollow stem.
Innovation Solution
A telescopic intramedullary nail design featuring a hollow stem and a rod with non-circular, complementary shaped sections at the distal ends, allowing for rotational constraint and easy extraction of both components with a single rotation, while avoiding the need for on-site cutting of the rod.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the rod is cut to measure on site during insertion, then the rod can be fitted into the hollow stem, but the rod may seize due to local deformation at the cut point
Solution Approach 1:
The rod is pre-cut to the correct length before insertion, and a countersink hole is pre-formed at the distal end to receive the cutting tool. This preliminary preparation eliminates the need for on-site cutting while ensuring smooth insertion without seizure.
2Ease of operation
If the rod is extracted by torsion and traction after insertion, then the rod can be removed from the bone, but the extraction process becomes extremely complex for the surgeon
Solution Approach 1:
The nail system is divided into two separable components: the hollow stem remaining in the bone and the rod that can be easily extracted. The rod is designed with a distal end that protrudes beyond the hollow stem, allowing it to be grasped and removed independently through a simple pull motion without complex torsional manipulation.
3Stability of the object's composition
If the threaded tip is fixed beyond the growth cartilage, then the rod remains stable during bone growth, but the extraction requires precise identification and manipulation of the threaded tip
Solution Approach 1:
The threaded tip is designed to be easily extractable from the growth cartilage. The thread geometry and material properties allow the tip to be removed through simple traction during extraction, eliminating the need for complex manipulation while maintaining stability during the growth phase.
Data Source
AI summary
A telescopic intramedullary nail for the treatment of fractures or deformations of long bones, such as for example in the case of osteogenesis imperfecta or pseudoarthrosis, extended along a longitudinal axis. The telescopic intramedullary nail may include a hollow stem and a rod telescopically coupled inside said hollow stem. A structure may constrain the hollow stem and said rod in rotation about said longitudinal axis during the insertion and/or during the removal of said telescopic intramedullary nail.