Flexible Washer Condylar Fracture Fixation
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Solution Overview
Problem
Current fixation devices for femoral fractures, particularly supracondylar and condylar fractures, often result in complications such as delayed union, infection, and mechanical failures due to invasive surgery and inadequate adaptation to irregular bone surfaces, leading to tissue impingement and pain.
Innovation Solution
A condylar fracture fixation system featuring an intramedullary nail with a longitudinally extending rod and flexible, radially outwardly threaded nuts and washers that can be rotated and deformed to fit the bone surface, allowing for improved compression and stabilization without protruding beyond the bone cortex, reducing the need for extensive screw turns and minimizing tissue damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If rigid washers are used with standard condyle screws, then the screw structure is simple and easy to manufacture, but the washers cannot adapt to irregular bone surfaces, causing tissue impingement and pain
Solution Approach 1:
The patent applies the dynamics principle by making the washer flexible rather than rigid, allowing it to deform and adapt to the irregular contours of the bone surface. The flexible washer can change its shape during insertion and compression to conform to the anatomical variations, thereby eliminating tissue impingement while maintaining structural simplicity.
Solution Approach 2:
The patent implements parameter changes by altering the physical properties of the washer from rigid to flexible, enabling it to dynamically adjust its shape. This parameter change allows the washer to accommodate irregular bone surfaces without requiring complex structural designs, thus resolving the contradiction between adaptability and device complexity.
2Productivity
If standard condyle screws with rigid washers are used, then the compression mechanism is simple, but multiple screw turns are required to achieve washer contact with the bone cortex, increasing procedure time
Solution Approach 1:
The flexible washer dynamically deforms during screw insertion to gradually adapt to the bone surface contours. This dynamic adaptation allows the washer to maintain contact with the bone cortex throughout the compression process, eliminating the need for multiple adjustment turns and significantly reducing the time required to achieve proper compression.
Solution Approach 2:
The flexible washer performs self-adjustment by automatically conforming to the irregular bone surface during insertion. This self-service capability eliminates the need for manual adjustment through multiple screw turns, as the washer autonomously adapts to the optimal position and orientation, thereby reducing procedure time while maintaining effective compression.
3Reliability
If invasive surgery with plates and screws is used to fixate femoral fractures, then the bone fragments can be stabilized, but considerable dissection is required causing devascularization and complications
Solution Approach 1:
The patent extracts the condyle screw from the traditional plate-screw fixation system, using it as a standalone intramedullary device. By removing the screw from the external plate structure and inserting it directly into the medullary canal, the procedure requires minimal soft tissue dissection, thereby preserving blood supply and reducing the risk of infection while maintaining effective fracture stabilization.
Solution Approach 2:
The flexible washer acts as an intermediary between the screw and the bone cortex, distributing the compression force evenly across the irregular bone surface. This intermediary function allows for effective stabilization with minimal insertion force and reduced soft tissue disruption, thereby lowering the risk of devascularization and infection compared to traditional plate-screw fixation.
4Force
If the condyle screw is inserted medially and compressed laterally, then fracture compression is achieved, but the fixed washer position may protrude beyond the bone surface and impinge on knee joint cartilage
Solution Approach 1:
The flexible washer dynamically adapts its shape during compression to conform to the bone surface contours. As the screw is inserted and compressed, the washer gradually deforms to match the anatomical variations, ensuring that it remains flush with the bone surface and does not protrude to impinge on the knee joint cartilage, while still delivering effective compression force.
Solution Approach 2:
The patent applies parameter changes by transforming the washer from a rigid structure with fixed geometry to a flexible structure that can change its shape and orientation. This parameter change enables the washer to adapt to the bone surface during compression, maintaining optimal contact without protruding beyond the cortex, thereby preventing cartilage impingement while preserving compression effectiveness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides enhanced stabilization and reduced complications by allowing precise adaptation to the bone surface, minimizing tissue impingement, and requiring fewer screw turns for effective fracture compression, thus promoting faster healing and reducing post-operative issues.
Implementation Method 1
a flexible washer (34, 36) mounted on an end of each of the first and second nuts (32) opposite the open end
Implementation Method 2
The inwardly extending threads or ridges of the first and second nuts (32) respectively engaging the outwardly extending threads or ridges of the rod first and second ends (12, 14)
Implementation Method 3
A condylar screw system includes a longitudinally extending rod which has first and second ends with each end having outwardly extending threads or ridges
Implementation Method 4
an intramedullary (IM) nail (100) which, after insertion into the femur extends in a proximal-distal direction
Data Source
Figure 1~1A
Figure 2~2A
Figure 2B~3
AI summary
A condylar fracture fixation system for use with an intramedullary nail includes a longitudinally extending rod (10) having first and second ends (12, 14), each end having outwardly extending threads or ridges. The rod (10) extends along a first longitudinal axis which extends in a medial-lateral direction in use. A first and second nut (30) is provided each nut having first and second ends. The second end of each nut (30) having an opening formed by a plurality of resilient legs (40) for respectively receiving the first and second ends of the rod. The second end of the first and second nuts include ridges or threads (44) extending into the opening in each nut. The inwardly (44) extending ridges of nuts respectively engaging the outwardly extending threads or ridges (12) of the rod. A flexible washer (34) is connected to the first end of each nut.