By Stefania Fatone, PhD, Ryan Caldwell, CP, FAAOP, and Julia Quinlan, PhD
Prosthetic and orthotic clinical care involves using custom-made devices to assist in the rehabilitation of people with physical impairments and disabilities. As such, it has long relied on the craftsmanship of prosthetists and orthotists. Although the results of such craftsmanship can be of tremendous benefit to the patient, it relies heavily on clinician experience and makes it challenging to achieve a consistent standard of care across the profession. As clinicians and researchers, we believe that emerging technologies can be used to standardize and therefore improve the efficacy of prosthetic and orthotic clinical care. As examples, emerging technologies can be used to standardize the process of residual limb shape capture and socket fabrication, processes that are foundational to the function of a prosthesis.
The prosthetic socket is the most critical component of a prosthesis given that it must fit intimately with the unique anatomy of the residual limb in order to transfer forces effectively and comfortably to the prosthesis while remaining firmly connected to the residual limb. Poorly fitting sockets can contribute to residual limb problems (eg, skin breakdown and pain), compromise the function of more distal components (eg, the knee and foot), and negatively affect overall function (eg, the ability to walk).
Fabricating an intimately fitting socket requires capturing the unique shape of the residual limb. The conventional and most commonly used method of capturing residual limb shape is through hand molding plaster of Paris or fiberglass bandages to the residual limb to create a negative mold. However, emerging technologies such as digital scanning and standing hydrostatic casting systems provide an alternative means of residual limb shape capture. In particular, standing hydrostatic casting, allows for residual limb shape to be captured while in the same weight-bearing conditions that are experienced in a socket, rather than relying on hand molding of the negative wrap and subsequent rectification of a positive plaster model to achieve the desired socket shape. Early research regarding standing hydrostatic casting suggests that less experienced clinicians can create more consistent socket shapes with satisfactory patient-reported socket fit outcomes.
The most recent version of the hydrostatic casting system combines pressure casting with magnetic field tracking to capture the residual limb shape digitally and allow for direct fabrication of the socket through fabrication processes such as 3D printing. A key advantage of direct fabrication methods such as 3D printing for socket fabrication is the control and repeatability it brings to socket construction as compared to manual fabrication via hand lamination. Variables such as socket thickness, compliance, and texture may all be controlled and reproduced as needed.
While use of these technologies in prosthetic and orthotic clinical care will standardize the fitting and fabrication of prosthetic and orthotic devices, it also fundamentally changes how clinicians work, reducing reliance on hand skills, and perhaps challenging our long-standing professional identity as master craftsmen. However, the ability to provide consistent and effective clinical care is the hallmark of modern medicine and must be embraced by the prosthetic and orthotic profession if we are to improve the provision of prosthetic and orthotic clinical care into the future.
Stefania Fatone, PhD, BPO(Hons), is a professor in the Department of Physical Medicine and Rehabilitation in the Northwestern University Feinberg School of Medicine, Evanston, Illinois. She is a long-standing member of the LER Editorial Advisory Board.
Ryan Caldwell, CP, FAAOP, is a Research Prosthetist at the Northwestern University Prosthetic-Orthotic Center in the Northwestern University Feinberg School of Medicine, as well as a Certified Prosthetist with Scheck & Siress Prosthetics and Orthotics in Schaumburg, Illinois.
Julia Quinlan, PhD, is a postdoctoral fellow at the Northwestern University Prosthetic-Orthotic Center in the Northwestern University Feinberg School of Medicine.