Prosthetic Sockets: REDUCING Steps for Manufacturing

1 PROSTHETIC SOCKETS: REDUCING STEPS FOR MANUFACTURING. Guerra.A.R.O,Costa Jr.J.C.A,Aquino,E.F.,Silva,L.G.,Lacerda,I.M.F and Queiroz,W.F “Federal University of Rio Grande do Norte, Department of Mechanical Engineering, Natal-RN- 59072-790- Brazil”

INTRODUCTION concerning the plaster negative cast. Instead the Nowadays some amputees may easily benefit from positive cast CAD information can be sent both the great enhancements presented by the latest limb straight to the shop floor environment or to a rapid prosthetic designs that have been incorporated with prototyping machine. Of course, the system also dynamic elastic response (DER) (Lee, 2006). allows some FEA analyses before the final value of However, the current Brazilian reality concerning the wall thickness is decided. patients assisted by the National Health Service (S.U.S) cannot afford such up-to-date technologies. RESULTS Therefore, the simple traditional rigid-shank The low cost electro-mechanic 3D scanner replaced prostheses are still preferred due to its low cost. the traditional measure-tapes and callipers used to Some procedures take on the very first step of the get residual limb surface information. prosthesis manufacturing process, not only in Brazil, A friendly computer interface providing both CAD and are still very inaccurate and outdated. For instance, CAE tools was united in a single package. It is measurements are made of the residual limb by using possible to interactively add/change loads, boundary ordinary home kind measure-tapes. First, dot markers conditions and wall thickness of the socket for FEA. are placed on the residua and, next, the plaster negative cast is produced. The integrated system does not require the plaster negative cast to be built and, therefore, the On the other hand, since early 90´s some researches manufacturing process was reduced by one step. have been working on the development 3D optical surface scanners (OSS) and have made interesting DISCUSSION evaluation of several others measurements techniques such as x-ray computed tomography Certainly the developed 3D OOS appliance means (SCXT), electromagnetic digitizer and callipers an improvement on measurements accuracy and (Commean,1998). quality of the final socket. It also means a step forward improved prosthetic fit assessment. More recent works are focused on applying computer tools such as finite element modeling for investigating The hybrid CAD/CAE package intergraded as a single stress distribution, deformability, structural integrity piece avoids the user from moving between packages and skin temperature between residual limb and and facilitates up to downstream tasks. Furthermore, prosthetic socket (Jia,2004, Lin,2004 Liu,2004) one step less in the manufacturing process means costs and time reduction. The low quality of the sockets produced by some archaic methods often may cause amputees to Similar results were archived by a rapid prototyping experience discomfort and increase the risk of framework (Faustini,2006) and validated as suitable pressure sores. Furthermore, time spent on this for prosthetic socket manufacturing. Future work need handmade plaster negative cast is extremely long. to be done in order to consider pre-loading stress as it happens in real life situations. In order to overcome some of these problems without considerably increasing the manufacturing costs, this CONCLUSION paper presents a reverse engineering based system Combining reverse engineering, CAD and CAE consisting of a very low cost electro-mechanic 3D concepts has proved to be an efficient and feasible scanner integrated with specific academic CAD/CAE mean to both visualize and improve prosthetic software. The main goal is to reduce one step on this sockets manufacturing process. manufacturing process while achieving accuracy and good-fitting prosthesis. Further improvement to the CAE model of this system will be of great help for prosthesis designers and may METHOD overcome some well known difficulties of commercial The approach used in this research was based on packages concerning composite material analyses. reverse engineering concepts integrated with CAD and CAE techniques. First, a low cost electro- REFERENCES mechanic 3D scanner was designed to capture Commean.,P.K. et al, J Rehabil Res Dev, 3, 267-78,1996 Faustini M.C. et al,IEEE-Neural Syst Rehab Eng, 3, 370-7, 2006. residua limb’s geometric surface information. Next, a Jia, X. et al, J. Biomech, 9, 1371-77 CAD software was developed to automatic Lee,W.C.et al,IEEE-Neural Syst Rehab Eng, 3, 370-7, 2006. Lin CC. et al, J. Med Eng Phys, 1, 1-9,2004. reconstruct the anatomic 3D representation of its Liu Z. et al, J. of Biomed Eng, 4, 562-5,2004. corresponding plaster positive cast of the socket. This procedure eliminates the manufacturing step

12th World Congress of the International Society for Prosthetics and Orthotics Vancouver, Canada, July 29 –August 3, 2007