Telescopic Pediatric Hip Screw for Growth-Compatible Fixation
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Solution Overview
Problem
Existing surgical treatments for Slipped Capital Femoral Epiphysis (SCFE) in adolescents often result in complications such as pin dislodgement, intra-articular irritation, altered bone architecture, and impaired growth due to improper screw designs that do not accommodate bone growth, requiring multiple sizes and pre-operative planning, and lack stability.
Innovation Solution
An adjustable pediatric hip screw system comprising a female component with a threaded shaft and head, a male component with partial threading and self-tapping features, an end cap, and a stimulation spring, allowing for adjustable length and stable fixation without disrupting bone growth, using an inserter with a nut and connector for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple sizes of screws are used to accommodate different femoral neck lengths, then the adaptability to various bone anatomies is improved, but the device complexity and surgical planning requirements increase
Solution Approach 1:
The patent implements a universal screw design where a single screw size can accommodate different femoral neck lengths through telescopic adjustment. The male and female components can slide relative to each other, allowing the effective length to be adjusted intraoperatively to match various bone anatomies without requiring multiple pre-selected screw sizes
Solution Approach 2:
The screw incorporates dynamic telescopic components that allow length adjustment after insertion. The male component can move axially within the female component, enabling the fixation device to adapt to different bone lengths and growth stages without requiring pre-operative measurement and selection of specific screw sizes
2Stability of the object's composition
If the threaded head diameter of the female component is substantially larger than the smooth shaft diameter, then the fixation stability is improved, but the epiphysiodesis effect intensifies and bone growth is significantly slowed
Solution Approach 1:
The patent applies different threading characteristics to different portions of the screw. The female component has threading only in its distal portion that engages with the femoral neck cortex, while the proximal portion remains smooth to minimize interference with the growth plate. This localized threading approach provides adequate fixation stability without causing extensive epiphysiodesis
Solution Approach 2:
The screw is divided into distinct functional segments: a threaded distal portion for cortical engagement and fixation stability, and a smooth proximal portion for growth plate compatibility. This segmentation allows each portion to perform its specific function optimally without compromising the other
3Stability of the object's composition
If the female component is inserted initially requiring removal of higher volume of bone, then the initial fixation is achieved, but the femoral neck natural architecture is changed drastically and healing is delayed
Solution Approach 1:
The patent reverses the traditional insertion sequence by first inserting the male component into the epiphysis and then receiving the female component telescopically. This inverted approach allows the female component to be guided into position with minimal bone removal, preserving the femoral neck architecture while still achieving secure fixation
4Stability of the object's composition
If the male component head is buried beyond the lateral cortex of the femur, then the fixation stability is improved, but positive migration of the assembled screw occurs
Solution Approach 1:
The patent employs a telescopic nested structure where the male component is received within the female component. The male component head remains partially exposed or flush with the lateral cortex rather than being buried, preventing positive migration while the nested telescopic structure provides the necessary fixation stability through the interlocking threaded portions
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
Provides stable fixation and growth compatibility by minimizing bone disruption, reducing complications, and allowing for a single-size solution adaptable to various femoral neck lengths, thus ensuring effective treatment with reduced surgical complexity and improved outcomes.
Implementation Method 1
a stimulation spring nested between the male component and the end cap
Implementation Method 2
a male component with partial threading and self-tapping features
Data Source
AI summary
An adjustable pediatric hip screw system designed for easy intra-operative length adjustment using a specialized inserter. The system ensures bone stimulation through the integration of a spring positioned between the end cap and the male component. Additionally, the screw's unique geometry effectively hinders cell migration through the physis. The female component is equipped with a dual flat-shaped shaft, which can be achieved either internally or externally through specific manufacturing processes. The male component is engineered to match the form of the female component, featuring a double flat to prevent rotation and a distal feature facilitating insertion into the femoral head.