Proximal Humerus Fixator with Segmented Support Blades
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Solution Overview
Problem
Current treatments for proximal humeral fractures, particularly comminuted fractures, lack effective inner side support, leading to insufficient holding force and risk of nails entering the joint, which impairs shoulder joint function and hinders postoperative recovery.
Innovation Solution
A proximal humerus fixing device with a groove for medullary cavity support, featuring a first contact portion with a plane structure, a second contact portion for the greater tuberosity, anti-rotation nails, and locking nails, designed to provide stable mechanical support without damaging the medullary cavity, using materials like titanium alloys and memory alloys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If intramedullary nail fixing is used, then inner side support is improved, but the fixing on the head of the humerus is limited and nails may enter the joint
Solution Approach 1:
The intramedullary nail is divided into multiple functional segments: a proximal expansion section with blade structures for anchoring in the humeral head, a middle smooth section for blood flow preservation, and a distal locking section. This segmentation allows each part to perform its specific function - the expansion section provides reliable head fixation without joint penetration, while the locking section ensures shaft stability.
Solution Approach 2:
Different sections of the nail have different structural properties tailored to local requirements: the proximal end has expandable blades for secure head attachment, the middle section is smooth to preserve medullary blood supply, and the distal end has locking mechanisms for shaft fixation. This local differentiation resolves the contradiction by providing strong support where needed while avoiding harmful effects in other areas.
2Strength
If locking steel plates with nail locking technology are used, then fixing strength is improved, but effective inner side support is still absent and nails may enter the joint
Solution Approach 1:
The intramedullary nail acts as an intermediary element that provides internal support from within the medullary cavity, complementing the external locking plate. The nail's expansion blades engage the cancellous bone of the humeral head, creating an internal scaffold that prevents nail migration and joint penetration, while the plate provides external compression and stability.
3Ease of manufacture
If shoulder hemiarthroplasty is performed, then fracture fixation is achieved, but poor heeling or absorption of the greater tuberosity may occur leading to loss of moment arm
Solution Approach 1:
The intramedullary nail is inserted and expanded in the medullary cavity before final plate fixation, establishing internal support and alignment. The expansion blades are deployed to engage the humeral head bone structure prior to loading, ensuring proper positioning and preventing subsequent tuberosity malhealing that would compromise the moment arm.
4Strength
If intramedullary nails are used, then inner side support is provided, but the nails are not matched with the internal structure of the medullary cavity affecting blood supplying
Solution Approach 1:
The nail provides partial support through the smooth middle section that allows blood flow, while concentrating the fixation action at the proximal expansion blades and distal locking sections. This partial action approach ensures adequate mechanical support without requiring complete medullary cavity occupation, thereby preserving blood supply channels in the middle segment.
Solution Approach 2:
The nail structure is differentiated into zones with different properties: the proximal expansion zone for fixation, the middle smooth zone for blood flow preservation, and the distal locking zone for shaft stability. This local quality differentiation provides necessary support while minimizing damage to medullary blood supply in the intermediate region.
Data Source
Figure 1~2
AI summary
Disclosed is a device for fixing the proximal humerus, which comprises: a fixator (1), a main nail (2), an anti-rotation nail (3) and a locking nail (4), wherein the fixator (1) is set in the medullary canal of the proximal humerus, thereby matching the medullary canal of the proximal humerus; the upper end of the fixator (1) comprises a first contact part (11) and a second contact part (12); the first contact part (11) is in contact with the head of the humerus and has a planar structure; the second contact part (12) is in contact with the greater tubercle of the humerus and has the shape of a bulge; the distal end of the lower end (13) of the fixator (1) has the shape of a bullet, the lower end (13) of the fixator (1) not being in contact with the medullary canal; the main nail (2) is used for fixing the humerus head and the first contact part (11); the head of anti-rotation nail (3) enters the humerus head and the tail thereof is fixedly connected to the fixator (1); and the locking nail (4) is arranged at the lower end (13) of the fixator (1) for fixedly connecting the fixator (1) and the humeral shaft. The fixing device has a good treatment effect for the fixing of severe comminuted fractures of the proximal humerus with or without association with shoulder dislocation, and has a low risk of surgery.