Seamless Compression Knit Closure for Prosthetic Stockings
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Solution Overview
Problem
Existing compression knitted fabrics for prosthetic stockings face challenges in achieving a seamless, comfortable fit without skin irritation, and in precisely adjusting the compression pressure to conform to the shape of an amputated limb while maintaining a gradual pressure profile.
Innovation Solution
A method for producing a compression knit fabric that involves knitting a tubular section with elastic weft yarn integrated via tuck stitches, followed by a seamless reduction in stitches to form a dome-shaped end, allowing for a customizable fit and pressure profile adjusted to the limb's shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a circular pad or knitted end cap is sewn onto the distal end of a circular knitted compression stocking to close the round opening, then the distal end is closed and can conform to the limb, but a seam is created that causes thickening, distorts the compression pressure progression, and leads to friction and skin irritations
Solution Approach 1:
The knitting process is divided into two sections: a first tubular section with a constant number of stitches, and a second section where stitches are successively reduced to form the dome-shaped closed end. This segmentation allows the fabric to transition smoothly from tubular to closed without requiring a separate fastening element that would create a seam.
Solution Approach 2:
The knitting process continues seamlessly from the first tubular section into the second section where stitches are reduced. The knitting machine operates continuously without interruption, transferring stitches from active to inactive needle beds to gradually close the tube while maintaining the continuous knitted structure without seams.
2Ease of manufacture
If longitudinal seams are used to join two flat knitted parts to form a compression stocking, then the stocking can be constructed from flat pieces, but the seams impair the pressure distribution and cause skin irritation on the limb
Solution Approach 1:
Instead of joining two flat pieces together to form a tube (which would require seams), the invention starts with a tubular knitted structure and closes the distal end by reducing stitches in place. This inverts the traditional construction approach, eliminating the need for seam joining while maintaining ease of manufacture through continuous knitting.
3Adaptability or versatility
If elastic knitting thread is used to produce a stretchable knit that expands when applied to an amputated limb, then the stocking can accommodate the limb shape, but it is difficult to precisely set the desired compression pressure and generate a gradual pressure profile
Solution Approach 1:
The knitting density is varied locally along the length of the stocking. The first tubular section maintains a constant knitting density, while the second section progressively increases knitting density as stitches are reduced. This creates a gradual pressure profile where compression is highest at the distal end and decreases toward the proximal end, precisely controlling the pressure distribution without requiring post-manufacturing adjustments.
4Force
If the distal end of the prosthetic stocking is knitted with a dome-shaped closed end to provide high compression pressure on the amputated limb, then therapeutic compression is achieved, but it is difficult to achieve the desired seamless construction with precise pressure control
Solution Approach 1:
The knitting process dynamically transitions from a tubular configuration with constant stitches to a closed dome-shaped end by successively reducing stitches. The knitting machine adjusts the number of active stitches in real-time during the knitting process, allowing the fabric to morph from an open tube to a closed end while maintaining continuous production and precise control over the final compression characteristics.
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 method ensures a comfortable, seamless fit without skin irritation and allows for precise adjustment of compression pressure, providing a gradual pressure profile that minimizes irritation at the sensitive end of the amputated limb.
Implementation Method 1
compression knitted fabrics for prosthetic stockings are knitted from an elastic knitting thread, e.g. a wound thread with an elastic elastane core thread, in order to produce a stretchable knit which can expand when applied to an amputated limb and thus exert a compression pressure depending on the stretch
Implementation Method 2
the prosthetic stockings are formed from a compression knit which exerts a compressive effect on an amputated limb of a patient in order to therapeutically compress the limb stump. Such a compression therapy can suppress swelling of the limb stump caused by edema
Data Source
AI summary
A method for producing tubular compression knitted fabric includes: knitting a tubular first section of a basic knitted fabric forming stitches from at least one knitting yarn along a knitting direction, with a plurality of rows of stitches following one another in the knitting direction and an elastic weft yarn bound into the stitches via tuck stitches; and seamlessly knitting of a second section onto the first section along the knitting direction. In the second section viewed in the knitting direction, the number of stitches is successively reduced at least in some of the successive rows of stitches by transferring of stitches, thereby forming a closed dome-shaped end at the distal end of the second section by a reduction of stitches. The compression knitted fabric is usable to create prosthetic stockings for an amputated limb to apply compression pressure with a defined pressure profile without causing skin irritation.