Cannulated Titanium Screw for Flat Foot Correction
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Solution Overview
Problem
Existing surgical methods for correcting extremely flat feet in children require invasive procedures, leading to prolonged recovery, screw breakage, premature loosening, and tissue damage, with existing screws often failing to provide long-term correction due to material resorption or poor design.
Innovation Solution
A titanium alloy screw with a conical head and apex thread, designed for minimal invasive insertion through a small skin incision, providing increased strength, ease of placement, and self-tightening properties to prevent loosening, and easy removal without damaging surrounding tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional surgical methods are used to correct flat feet, then the correction can be achieved, but the operative area must be opened widely (30-50mm incision) causing tissue damage and prolonged recovery
Solution Approach 1:
The surgical procedure is segmented into two separate incisions: a small first incision (8mm) for screw insertion and a second incision for wire removal. This segmentation allows minimal invasive insertion while maintaining correction effectiveness, resolving the contradiction between reliable correction and tissue damage.
Solution Approach 2:
A Kirschner wire is used as an intermediary tool to guide the screw into the correct position through the small incision. The wire acts as a mediator that enables precise screw placement without requiring wide surgical exposure, thus achieving reliable correction with minimal tissue damage.
2Ease of operation
If ordinary head screws are used, then insertion is possible, but the head can catch on the heel bone edge causing instability and premature loosening
Solution Approach 1:
The screw head is designed with an asymmetric conical shape with a rounded apex instead of a symmetric spherical head. This asymmetric design prevents the head from catching on the heel bone edge while maintaining ease of insertion, resolving the contradiction between operational ease and screw stability.
Solution Approach 2:
The screw head features a conical shape with a rounded apex rather than sharp edges or flat surfaces. This curved, spheroidal design allows smooth insertion and prevents mechanical interference with the heel bone edge, ensuring long-term stability while maintaining ease of operation.
3Length of moving object
If screws with thin necks are used, then insertion through small incision is possible, but the screw breaks easily before correction is completed
Solution Approach 1:
The screw exhibits local quality variations: a thin canulated shaft for flexibility and small incision insertion, combined with a reinforced conical head and apex thread for strength. This localized differentiation allows the screw to be inserted through small incisions while preventing breakage during the correction period.
Solution Approach 2:
The screw is made from titanium alloy, a composite material that provides high strength-to-weight ratio. This material choice enables the screw to have sufficient strength to prevent breakage while maintaining a slender profile for minimal invasive insertion, resolving the contradiction between insertion depth and screw strength.
4Ease of manufacture
If resorptive screws are used, then removal is unnecessary, but the screws break after six months and do not provide long-term correction
Solution Approach 1:
The screw material parameters are specifically selected (titanium alloy with controlled properties) to prevent resorption while maintaining biocompatibility. This parameter optimization allows the screw to remain stable and functional for the required 30-month correction period, unlike resorptive screws that degrade too quickly.
5Ease of operation
If conventional screws are used without self-tightening feature, then insertion is straightforward, but premature loosening occurs in 5-7% of patients
Solution Approach 1:
The conical head design enables the screw to self-tighten into the bone as it is inserted, without requiring additional tightening mechanisms or procedures. This self-service feature prevents premature loosening while maintaining insertion simplicity, resolving the contradiction between operational ease and screw retention.
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 screw achieves immediate and permanent correction with reduced tissue damage, minimizing post-operative complications and allowing for magnetic resonance examinations, while maintaining stability and preventing breakage and loosening over the required correction period.
Implementation Method 1
The screw is made out of titanium alloy, which gives it a particular strength
Implementation Method 2
the head of the screw is bigger and conical by its shape, and the screw does not have a thin neck. The screw, as it is positioned, sets into the bone by self-tightening into it
Implementation Method 3
The point of the screw has apex thread, which also lessens the lesion of the bone while positioning it
Implementation Method 4
it can be inserted through a small skin gap directed by Kirschners's guide-wire (it is canulated)
Implementation Method 5
The screw is made out of titanium alloy, which gives it a particular strength, and the patient can undergo magnetic examinations, if there is any need for such while the screw is implanted
Data Source
Figure 1
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AI summary
The canulated titanium implant (screw) for correction of flat feet in children characterized by that: a) the diameter of the stem is D=4,8mm±25%, recommended 4,8mm±10%, and especially recommended 4,8mm, b) it is canulated, whose diameter is C=2mm+25%, recommended 2mm±10%, and especially recommended 2mm, c) the screw-thread height is l,15mm±25%, recommended l/15mm±10%, and especially recommended 1,15mm, d) on the point of the screw, which ends at the angle of 90°, on the apex thread are trisect cuts at the angle of 120°. The edges of the apex thread are cut at the angle of 55°. At the very top of the point of the screw, the trisect cuts of the apex thread go inward the tunnel in the length of the screw by 1,5mm, e) this type of the point replaces the use of the drill and the tapping device.