Socket Manufacturing Research Articles

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Purpose Develop a technology of manufacturing silicone sockets for functional hand prosthesis. Methods The technology of fabricating sockets for functional hand prosthesis made of high temperature vulcanization (HTV) silicone was developed and tested for the first time in the practice of domestic prosthetics, including the traditional stages of molding, positive reproduction, and manufacturing of sockets. However, there are technological peculiarities in each of the stages that enable to manufacture a comfortable individual full-contact socket for hand prosthesis made of silicone that was successfully used in active and functional prostheses and prostheses with external power in patients with congenital and amputation hand defects. Results The technology has a number of advantages over traditional ones, as it provides comfortable conditions for full contact and partial loading of the residual segment of a clubshaped hand stump in the liner socket of the prosthesis. These properties of the liner socket allow the production of the most skeletonized carrying socket made of composite material for reliable attachment of the components of functional hand prostheses to it. Conclusion Successful trials of the liner sockets of the hand prosthesis made from HTV silicone created the conditions for a wider application of this silicone brand in the manufacture of a new generation of sockets for upper and lower limb prosthesis.

Partial Foot Amputation, Finite Element Analysis of Foot and Manufacturing of Prosthtic Sockets: A Review

Partial Foot Amputation, Finite Element Analysis of Foot and Manufacturing of Prosthtic Sockets: A Review

The use of a direct manufacturing prosthetic socket system in a rural community in South Africa: A pilot study and lessons for future research.

Challenges exist with the provision of appropriate mobility assistive devices in rural areas. The use of the direct manufacturing prosthetic socket system is a possible solution to these challenges. The objective of this study was to test and explore the clients' perspectives with the application of this device. Within a mixed-methods approach, a longitudinal sequential explanatory design was applied. The Orthotic and Prosthetic User's Survey was administered to explore the use of the direct manufacturing prosthetic socket system in terms of function, health-related quality of life and client satisfaction. A conveniently selected sample of 21 individuals who suffered a unilateral trans-tibial amputation was included. Data were collected at 1, 3 and 6 months post fitting, and two focus group discussions were also administered. Of the 21 participants recruited, 11 returned for follow up. Although participants reported favourably about the prosthesis, their scores were generally worse than the norms with regard to function and quality of life. Participants highlighted the need for improvement in the cosmetic appearance of the prosthesis. The direct manufacturing prosthetic socket system could be considered as an alternative technique of socket manufacturing for individuals living in rural areas due to the shorter manufacture time and promising initial results, but further research on this topic with a bigger sample is recommended. Clinical relevance The direct manufacturing prosthetic socket system may be considered as an alternative to the traditional prosthetic socket manufacturing technique used in South Africa. As this device requires only one visit and therefore decreased travel by the patients to the hospitals, it could be applicable to more amputees who cannot return to hospital post discharge.

Determinants of Metals Exposure to Metalworking Fluid Among Metalworkers in Taiwan

ABSTRACT Metalworking fluids (MWFs) aerosols are known to have carcinogenic potential to humans that monitoring of MWFs is necessary to reduce risks. This study summarizes biological monitoring and occupational hygiene findings from a survey of metalworkers exposed to heavy metals in a socket manufacturing plant. Manganese, nickel, iron, copper, chromium, and zinc were selected for target metals. Air samples were collected and postshift urines were obtained from the thread cutting workers and punch press machine operators. There were positive correlations between the airborne concentrations of Cr, Mn, as well as Zn and the corresponding levels of urine for the exposed groups. Therefore, the integration of biological and environmental monitoring is feasible for Cr, Mn, and Zn. The results indicated significant correlations between the levels of Cu, Cr, Fe, as well as Zn from the air and sump MWFs at thread cutting and punch press sites.

A Variable-Impedance Prosthetic Socket for a Transtibial Amputee Designed from Magnetic Resonance Imaging Data

ABSTRACTThis article evaluates the design of a variable impedance prosthetic (VIPr) socket for a transtibial amputee using computer-aided design and manufacturing (CAD/CAM) processes. Compliant features are seamlessly integrated into a three-dimensional printed socket to achieve lower interface peak

Computer-socket manufacturing error: How much before it is clinically apparent?

The purpose of this research was to pursue quality standards for computer-manufacturing of prosthetic sockets for people with transtibial limb loss. Thirty-three duplicates of study participants' normally used sockets were fabricated using central fabrication facilities. Socket-manufacturing errors were compared with clinical assessments of socket fit. Of the 33 sockets tested, 23 were deemed clinically to need modification. All 13 sockets with mean radial error (MRE) greater than 0.25 mm were clinically unacceptable, and 11 of those were deemed in need of sizing reduction. Of the remaining 20 sockets, 5 sockets with interquartile range (IQR) greater than 0.40 mm were deemed globally or regionally oversized and in need of modification. Of the remaining 15 sockets, 5 sockets with closed contours of elevated surface normal angle error (SNAE) were deemed clinically to need shape modification at those closed contour locations. The remaining 10 sockets were deemed clinically acceptable and not in need modification. MRE, IQR, and SNAE may serve as effective metrics to characterize quality of computer-manufactured prosthetic sockets, helping facilitate the development of quality standards for the socket manufacturing industry.

Central fabrication

It is estimated that only 24% of practitioners use CAD/CAM regularly. Socket manufacturing error may be a source of the limited use of central fabrication. The purpose of this study was to investigate the differences in shape between computer-manufactured, centrally fabricated carved models and electronic file shapes, to determine if carving was a major source of socket manufacturing error in central fabrication. Experimental, mechanical assessment. Three different trans-tibial model shapes were sent electronically to each of 10 central fabrication facilities for the fabrication of positive foam models. A custom mechanical digitizer and alignment algorithm were used to measure the model shapes and then compare them with the electronic file shapes. Volume differences between the models and the electronic file shapes ranged from -4.2% to 1.0%, and averaged -0.9 (SD = 1.1)%. Mean radial error ranged from -1.2 mm to 0.3 mm and averaged -0.3 (SD = 0.3) mm. Inter-quartile range was between 0.3 mm and 2.7 mm and averaged 0.6 (SD = 0.5) mm. The models were significantly smaller than sockets made from the same electronic file shapes (p < 0.01), but the range of mean radial error and the interquartile range were not significantly different between the models and sockets. The results demonstrated that there was considerable variability in model quality among central fabricators in the industry, and that carving was not the sole source of socket fabrication error. The results provide insight into the severity and nature of carving error by central fabrication facilities. Because we found a wide range of model quality, there is not a consistent fabrication problem across the industry, but instead some central fabrication facilities practice the art of model fabrication better than others.

Knowledge-based System for Guided Modeling of Sockets for Lower Limb Prostheses

AbstractThis paper presents a 3D CAD system to design sockets of lower limb prostheses, both transfemoral and transtibial. The proposed system, named Virtual Socket Laboratory, can be seen as a virtual laboratory where the user has at her/his disposal virtual tools that permit to emulate the procedures applied by orthopaedic technicians during the traditional socket manufacturing. The module is centred on the digital model of the patient and is based on the specific domain knowledge to guide the user during socket modelling suggesting the most appropriate design rules and procedures. First, main steps of the new design-modelling process and system functionalities are presented. Then, for each step, procedures carried during the traditional process, how they are executed with the new module and tools specifically developed are described.

The effects of new technology adoption on employee skills in the prosthetics profession

Rapid manufacturing (RM) is an emerging technology that is set to revolutionize how products are manufactured. Past research has centred on processes, materials and costing, neglecting the vital issue of how the implementation of this new technology will affect the skills of workers. This work aims to evaluate how the skills of professionals working in the field of prosthetics are likely to be affected by the introduction of RM. Currently a highly skilled, manual process, this paper explores the hypothesis that the manufacture of prosthetic sockets would change fundamentally with the introduction of RM technology. This was evaluated through the use of the job characteristics model, which assesses the skills change and job satisfaction implications of applying new technology to traditional manufacturing processes. Conclusions showed that RM would have a significant impact on job roles in the prosthetics industry. Analysis found a positive outlook for the prosthetist, with the new technology increasing computer-based skills, and traditional prosthetic skills continuing to be used. The prosthetic technician bears the major impact, deskilled by the loss of many of the craft skills. However, the new role may appeal to the younger generation, and lowered skill requirements may help increase prosthetics services worldwide.

Review of Research on Prosthetic Devices for Lower Extremity Amputation

The literature on lower extremity prostheses from 1989 to 2006 has been reviewed in this article. New technologies, such as the microprocessor-controlled prosthetic knees and energy-storing/return prosthetic feet, are recent advances in the prosthetic field. Despite the extensive research to date in the areas of socket design and manufacturing, and alignment of prostheses for optimum gait analyses, problems persist in the field. Difficulties in obtaining a comfortable socket fit, prostheses weight and alignment guidelines, and the ability to rapidly manufacture a prosthetic socket that can accommodate the changing sizes of the residual limb persist. Furthermore, no prosthetic device can adjust to the typical movements of the human gait. These areas provide opportunities for further research and development.

A preliminary investigation into the development of 3-D printing of prosthetic sockets

The socket is considered an element of major importance in the makeup of a prosthesis. Each socket is a tailor-made device, designed to fit the unique geometry of the patient's residual limb. The design and manufacture of a prosthetic socket traditionally has been a manual process that relies on the use of plaster of Paris casts to capture the shape of the patient's residual limb and then artisan fabrication techniques to manufacture the socket. Computer-aided design and manufacturing technologies have overcome some of the shortcomings of the traditional process, but the final manufacture of the prosthetic socket is still performed manually. Rapid prototyping (RP), a relatively new class of manufacturing technologies, creates physical models directly from three-dimensional (3-D) computer data. Previous research into the application of RP systems to the manufacture of prosthetic sockets has focused on expensive, high-end technologies that have proven too expensive. This paper investigates the use of a cheaper, low-end RP technology known as 3-D printing. Our investigation was an initial approach to using a technology that is normally associated with producing prototypes quickly, some of which could not be manufactured by alternative means. Under normal circumstances, these printed components are weak and relatively fragile. However, comfortable prosthetic sockets manufactured with 3-D printing have been used in preliminary fittings with patients.

A CASD/CASM method for prosthetic socket fabrication using the FDM technology

As an application of the computer aided design and computer aided manufacturing (CAD/CAM) technology in prosthetics, computer aided socket design and computer aided socket manufacturing (CASD/CASM) is becoming an active field in the prosthetics research. In this paper, a CASD/CASM method for prosthetic socket fabrication is described in detail. This is different from other fabrication methods in its novel combination of the CAD/CAM technology with fused deposition modeling (FDM) technology. Prosthetic sockets for volunteer amputees have been designed and fabricated in a FDM machine. In order to test the fabrication result, a final product was used to perform a clinical trial and some results are reported. In addition, the deficiency of the long fabrication time is addressed and some feasible solutions are discussed.

AN APPROACH FOR THE CORRELATION OF EMG SIGNALS AND THE RECTIFICATION OF PTB SOCKETS

Prosthesis is often used to restore the appearance and functional mobility to individuals following limb amputatio n. The purpose of this study is to investigate the correlation between the electromyogram (EMG) signals with the rectification of patellar tendon bearing (PTB) socket. Six PTB sockets are manufactured with different compression depths at the patellar tendon region. Experiments for the subject are carried out to obtain the EMG signals using EMG telemetry system. From this study, it is found that there exists some kinds of pattern as the depths of PTB rectification is changed. As the PTB rectification depth is increased, the EMG activity rises generally yet in an N pattern for the quadriceps group for both left and right legs of the amputee. The results of this case study will lead to an appropriate range of rectification depths for prosthetists in the manufacturing of PTB sockets, and perhaps the identification of the most suitable depth for optimum transtibial amputee ambulation.

Finite element modelling of a residual lower-limb in a prosthetic socket: a survey of the development in the first decade

A review is presented of the existing finite element models developed from 1987 to 1996 for the biomechanics of lower-limb prostheses. Finite element analysis can be a useful tool in investigating the mechanical interaction between the residual limb and its prosthetic socket, and in computer-aided design and computer-aided manufacturing of prosthetic sockets. Various assumptions and simplifications are made in these models to simplify the actual problem with complex geometry, material properties, boundary and interfacial conditions, as well as loading situations. The analyses can provide the information on the stress distribution at the stump/socket interface and within the residual limb tissues. More recently, nonlinear models have been developed taking into consideration the process of socket rectifications, the slip/friction conditions and material large deformation. The models so far developed have provided some basic understanding of the biomechanics. Comparison of the predictions of these models with experimental measurements indicated that the predicted stresses were within the ranges measured, although one-to-one correspondence was difficult to achieve. Further research is still required in order to improve these models to obtain higher precision in the results taking into account nonlinear and dynamic effects.

Automated fabrication of mobility aids (AFMA): below-knee CASD/CAM testing and evaluation program results.

In 1988 the Department of Veterans Affairs Rehabilitation Research and Development Service, under the directorship of Margaret J. Giannini, M.D., began a nationally directed computer-aided design and computer-aided manufacturing (CAD/CAM) research program for the Automated Fabrication of Mobility Aids (AFMA). Under this program CAD/CAM research and development centers were established at the Prosthetics Research Study in Seattle, WA; at Northwestern University and the VA Lakeside Medical Center in Chicago, IL; and at the VA Medical Center and New York University Medical Center in New York, NY. These three centers conducted a collaborative program: (a) to introduce CAD/CAM technologies to prosthetists, physicians, therapists, and rehabilitation health care professionals in the United States; (b) to evaluate the feasibility of using CAD/CAM systems in clinical prosthetics settings; (c) to test and evaluate the University College London-Bioengineering Center's and the University of British Columbia-Medical Engineering Resource Unit's respective systems for the computer-aided design and computer-aided manufacture of prosthetic sockets (CASD/CAM) for below-knee amputees; and, (d) to obtain quantitative data for refinement of the CASD/CAM systems tested, and for the development of new, enhanced, more efficacious, and expedient systems.

Computer-aided design and manufacture of an above-knee amputee socket

This paper describes the initial test results obtained from a newly developed computer-aided socket design (CASD) and manufacturing (CASM) process for above-knee amputees. Anthropometric measures taken from an amputee provided input information to a CASD system. Using these measurements, data from a reference shape library stored in the computer were selected and modified to create a unique socket shape reflecting the particular characteristics of the amputation stump. The resultant shape was produced as a ‘primitive’ test socket by a CASM process. Numerical shape data were then transferred to a CNC milling machine to construct a negative cast, from which the primitive socket was produced by a vacuum-forming procedure. The resultant primitive socket shape was fitted and the amputee was able to load the socket without discomfort. Some shape discrepancies were identified and the shape data were modified interactively by the CASD system to create a final socket shape. The final socket shape was manufactured and worn by the amputee during a 35 min walking trial. Subjective evaluation was that the socket provided comfort and control comparable with that of the conventional socket, and proved to be acceptable to the amputee. This was followed by a 2-month home trial which was also successful. The CASD socket shapes were compared numerically in area, shape and volume with data taken from the original socket worn by the amputee, a new socket made by conventional methods and a topographic model of the amputation stump. The final CASD socket shape compared favourably with that of a socket manufactured by conventional methods. Results indicated that by the use of the CASD/CASM process, it was possible to produce an above-knee prosthetic socket which provided comfort and control for the amputee.

A new directly moulded patellar-tendon-bearing socket

Silicone rubbers and casting tapes individually have previously been used in the manufacture of sockets (Swanson, 1972; Sweitzer, 1973; Ruder, 1977; Graves, 1980; Aqualite, 1982). The authors believe that the present combination of these materials to manufacture a directly moulded socket with a complete silicone rubber lining of variable thickness has not previously been described. The new socket, after addition of the modular components, allows fitting of an aligned below-knee prosthesis within three hours. The socket (Fig. 1.) is made directly on the below-knee stump, can be completed with experience in an hour and does not require the use of specialized equipment. The socket consists of an outer supportive Scotchflex layer inside which is a lining of soft smooth biocompatible silicone rubber of deliberately variable thickness to allow pressure tolerant areas to accept more load and pressure sensitive areas to accept less load (Fig.2). The thicker areas of silicone are produced by applying carefully cut Plastazote pads to the pressure sensitive areas. The thickness and extent of the pads is individually assessed according to the estimated sensitivity of the particular area (Fig. 3). The Scotchflex socket is then manufactured directly on the below-knee stump with these pads applied. The pads are then removed prior to insertion of a semi-liquid silicone rubber. Thus, when the socket with the liquid silicone rubber is re-applied to the stump, the space produced by the pads is filled by the rubber which then sets at room temperature. In this way a layer of variable thickness is produced.(ABSTRACT TRUNCATED AT 250 WORDS)

A software package for design and manufacture of prosthetic sockets for transtibial amputees.

A software package, written in Pascal, whkh automates the shape management process associated with fitting prosthetic sockets to transtibial (below-knee) amputees, is described. The system allows an operator to apply global and piecewise transformations, based upon clinkal measurements, to a primitive socket database. These transformations yield a modified socket database which defines the surface shape of a positive socket mold over which an amputee's prosthetic socket is formed. The mold is replicated using a computer numerkally controled milling machine, with the final socket being formed over this mold by a specialized vacuum former. Preliminary clinical trials indkate that this automated approach to shape management yields comfortable prostheses, with savings in time and cost over the traditional methods of prosthesis manufacture.

Socket design and manufacturing technique for through-knee stumps.

This paper describes a socket design and manufacturing technique for through-knee stumps, based on 14 years experience with 290 prostheses. The bulbous shape of the stump and its full end-bearing quality requires a socket which has very little resemblance to above-knee sockets. The requirements of the through-knee socket are listed and the manufacturing technique is described and illustrated in detail. Emphasis is put on the quality of the negative plaster mould. The socket is manufactured according to the double wall technique commonly used in below-knee sockets. It provides a maximum of comfort and cosmesis without extra costs.