Comparison of CAD-CAM and hand made sockets for PTB prostheses

A scoping review of digital fabrication techniques applied to prosthetics and orthotics: Part 1 of 2-Prosthetics

BACKGROUND

Traditionally, the manufacture of prostheses is time-consuming and labor-intensive. One possible route to improving access and quality of these devices is the digitalizing of the fabrication process, which may reduce the burden of manual labor and bring the potential for automation that could help unblock access to assistive technologies globally.

OBJECTIVES

To identify where there are gaps in the literature that are creating barriers to decision-making on either appropriate uptake by clinical teams or on the needed next steps in research that mean these technologies can continue on a pathway to maturity.

STUDY DESIGN

Scoping literature review.

METHODS

A comprehensive search was completed in the following databases: Allied and Complementary Medicine Database, MEDLINE, Embase, Global Health Archive, CINAHL Plus, Cochrane Library, Web of Science, Association for Computing Machinery, Institute of Electrical and Electronics Engineers, and Engineering Village, resulting in 3487 articles to be screened.

RESULTS

After screening, 130 lower limb prosthetic articles and 117 upper limb prosthetic articles were included in this review. Multiple limitations in the literature were identified, particularly a lack of long-term, larger-scale studies; research into the training requirements for these technologies and the necessary rectification processes; and a high range of variance of production workflows and materials which makes drawing conclusions difficult.

CONCLUSIONS

These limitations create a barrier to adequate evidence-based decision-making for clinicians, technology developers, and wider policymakers. Increased collaboration between academia, industry, and clinical teams across more of the pathway to market for new technologies could be a route to addressing these gaps.

Academia's Role to Drive Change in the Orthotics and Prosthetics profession

This position paper outlines the important role of academia in shaping the orthotics and prosthetics (O&P) profession and preparing for its future. In the United States, most healthcare professions including O&P are under intense pressure to provide cost effective treatments and quantifiable health outcomes. Pivotal changes are needed in the way O&P services are provided to remain competitive. This will require the integration of new technologies and data driven processes that have the potential to streamline workflows, reduce errors and inform new methods of clinical care and device manufacturing. Academia can lead this change, starting with a restructuring in academic program curricula that will enable the next generation of professionals to cope with multiple demands such as the provision of services for an increasing number of patients by a relatively small workforce of certified practitioners delivering these services at a reduced cost, with the expectation of significant, meaningful, and measurable value. Key curricular changes will require replacing traditional labor-intensive and inefficient fabrication methods with the integration of newer technologies (i.e., digital shape capture, digital modeling/rectification and additive manufacturing). Improving manufacturing efficiencies will allow greater curricular emphasis on clinical training and education - an area that has traditionally been underemphasized. Providing more curricular emphasis on holistic patient care approaches that utilize systematic and evidence-based methods in patient assessment, treatment planning, dosage of O&P technology use, and measurement of patient outcomes is imminent. Strengthening O&P professionals' clinical decision-making skills and decreasing labor-intensive technical fabrication aspects of the curriculum will be critical in moving toward a digital and technology-centric practice model that will enable future practitioners to adapt and survive.

Central fabrication: carved positive assessment

BACKGROUND

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.

OBJECTIVES

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.

STUDY DESIGN

Experimental, mechanical assessment.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

CLINICAL RELEVANCE

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.

A quantitative method for comparing and evaluating manual prosthetic socket modifications

Manually designed prosthetic sockets are difficult to evaluate since the hand-sculpting modification process does not retain the initial shape for comparison. A quantitative method for defining and comparing manual socket modifications was developed and integrated into the CADVIEW software package. The numerical comparison procedure consisted of a) digitizing premodification and post-modification models of a prosthetic socket, b) aligning these two shapes to a common axis (calculate cross section centroids, determine line of best fit through the centroids, rotate and move the line of best fit to a common axis), and c) displaying the differences in shape both numerically and using a color-coded three dimensional image. Alignment technique testing showed a between-radial-point average error of 2.5 mm using automatic alignment and 1.4 mm after further manual alignment adjustment. The between socket difference values were used to outline individual modifications and save these outlines to disk. Modification outlines from a series of patients were averaged to determine a prosthetist's general modification style. Averaged results from two prosthetists qualitatively supported the effectiveness of this procedure. This alignment and comparison system should help transfer hand-sculpting skills to prosthetic CAD/CAM systems, clinical research, and education for new clinicians.

Clinical evaluation of trans-tibial prosthesis sockets: a comparison between CAD CAM and conventionally produced sockets

This study is an evaluation, from the patient's point of view, of CAD CAM prosthesis sockets compared with conventional sockets. Twenty-two trans-tibial amputees were divided into two groups. One group was provided with a CAD CAM (CAPOD) socket, the other with a conventionally made one. After one month the groups were evaluated with regard to subjective experience, the judgement of a prosthetist and a physiotherapist, social variables and objective gait parameters. Then the groups switched over to the other type of socket, and after another month a new evaluation was performed. The study design was a single-blind study. In total 175 variables were evaluated. No difference was found between the two types of socket, except for a lower number of terry cloth stockings used in the CAD CAM socket. As the standard of conventional prosthetics in Sweden is considered to be high, the results were considered as satisfactory. The quality of the CAD CAM sockets was at least at the same level as conventionally made ones.

CAD CAM trans-tibial temporary prosthesis: analysis and comparison with an established technique

The purpose of this study was to evaluate the application of CAD CAM in the production of temporary trans-tibial prostheses. The CAD CAM system was assessed based on the number of socket attempts, number of prosthetic appointments, and temporary prosthesis rehabilitation time. These parameters were considered to be related to the quality of socket fit and were influenced by the entire interdisciplinary team including the patient. A concurrent prospective comparison between the CAD CAM system and an established fiberglass/pelite liner technique was also performed. Patients (n = 30), were fitted with either a conventional or a CAD CAM socket. Records were kept before and after discharge until the interdisciplinary team considered the patient ready for definitive prosthesis casting. After approximately 90 postoperative days, patients were deemed fit to proceed from their initial plaster cast prostheses to their temporary prostheses. The group fitted with conventional sockets had an in-patient rehabilitation phase of 10.5 +/- 15.0 days and required 2.9 +/- 1.1 prosthetic appointments. In-patients fitted with CAD CAM sockets required 5.1 +/- 1.8 appointments and were hospitalised for 23.6 +/- 15.0 days. The significantly increased rehabilitation duration and number of appointments (p = 0.01), were generally due to incorrect socket volume and/or inadequately modified relief/loading areas. In this study 67% of the patients fitted with CAD CAM sockets required at least one additional attempt. The clinical evaluation and modification of the temporary prostheses, including the decision to remake a particular socket, were carried out by the same prosthetist who cast the patients.(ABSTRACT TRUNCATED AT 250 WORDS)