Durability Testing of 3D-Printed Prosthetic Sockets
Abstract
Major extremity amputation is a prevalent conflict injury -- over 1700 Service-related amputations were performed during Operation Iraqi Freedom, Operation New Dawn, and Operation Enduring Freedom – and over 50,000 new amputations are performed in the Veterans Health Administration annually. For the new amputee, early provision and acceptance of a prosthesis is critical to successful rehabilitation. The use of Immediate Post-Operative Prosthesis (IPOP) and preparatory prosthesis can significantly help reduce phantom limb pain and sensation, increase the acceptance rate of and satisfaction with a prosthesis, reduce complications and in turn promote overall improved quality of life and prosthetic function. However, for a variety of reasons, prosthetic fittings do not always start early on following amputation. For example, prosthetic labs are not generally part of in-patient hospital settings, limiting access to these services in the acute post-amputation stage. Even if prosthetic services are outsourced, traditional methods of prosthetic fitting can take time. 3D printing of prosthetic sockets (and eventually, IPOPs) offers the potential for rapid fabrication within the acute-care setting; simple scanners and apps can be used to scan the limb that can be emailed to a skilled prosthetists and then designed, printed and returned to the patient within 24 hours. Moreover, the socket can be quickly and cheaply re-fabricated as the limb continues to shrink. Despite the promise that 3D printing holds in terms of reducing the time to initial fitting and in turn improving early rehabilitation outcomes, the extent to which 3D-printed devices are safe for daily use remains unknown. The objective of this project is to evaluate the durability of 3D-printed sockets using different printing material, compared to a standard laminated socket, where durability is defined as the mechanical performance of the prosthesis over time – e.g., will it crack or break after being continuously loaded for extended periods. The concept of durability is critical to understand for these new emerging materials and methods. Unlike standard lamination processes, 3D printing involves fusing together layers of materials, which may impact durability. Nonetheless, it is entirely possible that 3D-printed sockets are at least durable enough for use in short-term early rehabilitation. Quantifying the durability of 3D-printed sockets will help to establish standards, which are necessary before it is possible to conduct a trial evaluating outcomes with these devices. Durability testing involves exposing sockets to continuous, controlled, cyclic forces (loads) within a laboratory setting and observing how the shape of the socket changes over time (with increasing number of loading cycles). In this study, we will evaluate the durability of a standard laminated prosthetic socket (which is known to be sufficiently durable) and 3D-printed sockets using three different types of materials that are commonly used. All sockets will be fabricated by a skilled prosthetist based on the same residual limb. Prior to durability testing, an ultimate strength test will be performed on a single socket of each type to determine failure load. Durability testing will then be performed on two separate copies of each type of socket, using a load equal to half to the failure load (to increase the likelihood of observing failure during cyclic testing). We will modify an Instron testing machine with a custom-built loading fixture that will translate the point of application of the uniaxial testing device so that it better simulates dynamics of stance phase. The primary outcome will be the number of loading cycles before the socket fails, i.e., deforms more than 10 mm or develops a crack. From the stress versus number of cycles relationships (S-N curve) we will extrapolate data to understand the number of cycles that can be expected before failure under more physiological load
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 10, 2021
- Source ID
- W81XWH2010175
Entities
People
- Noah Rosenblatt
Organizations
- Rosalind Franklin University of Medicine and Science
- United States Army