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. 2016 Aug;38(8):801-6.
doi: 10.1016/j.medengphy.2016.04.019. Epub 2016 May 17.

Technical note: Computer-manufactured inserts for prosthetic sockets

Joan E Sanders  1 , Jake B McLean  2 , John C Cagle  3 , David W Gardner  4 , Katheryn J Allyn  5
Affiliations

Technical note: Computer-manufactured inserts for prosthetic sockets

Joan E Sanders et al. Med Eng Phys. 2016 Aug.

Abstract

The objective of this research was to use computer-aided design software and a tabletop 3-D additive manufacturing system to design and fabricate custom plastic inserts for trans-tibial prosthesis users. Shape quality of inserts was tested right after they were inserted into participant's test sockets and again after four weeks of wear. Inserts remained properly positioned and intact throughout testing. Right after insertion the inserts caused the socket to be slightly under-sized, by a mean of 0.11mm, approximately 55% of the thickness of a nylon sheath. After four weeks of wear the under-sizing was less, averaging 0.03mm, approximately 15% of the thickness of a nylon sheath. Thus the inserts settled into the sockets over time. If existing prosthetic design software packages were enhanced to conduct insert design and to automatically generate fabrication files for manufacturing, then computer manufactured inserts may offer advantages over traditional methods in terms of speed of fabrication, ease of design, modification, and record keeping.

Keywords: Accommodation; Amputee; CAD/CAM; Residual limb; Socket; Trans-tibial; Volume loss.

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Conflict of interest statement

There are no competing interests.

Figures

FIGURE 1
FIGURE 1
Custom frame and base used for socket digitization
FIGURE 2a–f
FIGURE 2a–f. Socket digitization and model formation
(a) Splines at the socket proximal and distal end. (b) Scanned patch regions of the socket. Each patch is a different color. (c) Holes in the scanned socket surface resulting from the digitization process. The holes illustrated are minor; additional scanning does not need to be performed for this socket. (d) Top-view of the socket illustrating axial splines. (e) Socket defined as a collection of 4-sided sections. (f) Solid model of a uniform thickness insert ready for fabrication.
FIGURE 2a–f
FIGURE 2a–f. Socket digitization and model formation
(a) Splines at the socket proximal and distal end. (b) Scanned patch regions of the socket. Each patch is a different color. (c) Holes in the scanned socket surface resulting from the digitization process. The holes illustrated are minor; additional scanning does not need to be performed for this socket. (d) Top-view of the socket illustrating axial splines. (e) Socket defined as a collection of 4-sided sections. (f) Solid model of a uniform thickness insert ready for fabrication.
FIGURE 3a,b
FIGURE 3a,b. Sectioning an insert for fabrication
(a) The insert was sectioned such that one boundary was at the tibial crest and the others posterior laterally and posterior medially. (b) Interlocking tabs were designed so that the inserts locked together when placed within the prosthetic socket.
FIGURE 4a–c
FIGURE 4a–c. Insert placed within prosthetic socket
(a) Two-sided laminating tape was applied to the proximal and distal edges of each insert piece. (b) Insert pieces were placed in the socket, one at a time. (c) Insert pieces interlocked once in place.
FIGURE 5a,b
FIGURE 5a,b. Shape differences between inserts and digital surfaces
(a) Measured right after insertion into the socket. (b) Measured after four weeks of wear. Scales are in mm.
FIGURE 5a,b
FIGURE 5a,b. Shape differences between inserts and digital surfaces
(a) Measured right after insertion into the socket. (b) Measured after four weeks of wear. Scales are in mm.
See this image and copyright information in PMC

References

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