Just in Time for the Annual Meeting: OTWorld Session Sneak Peeks
To enhance your experience at the OTWorld International Trade Show and World Congress, being held May 3-6 in Leipzig, Germany, this Online Exclusive presents additional details about several session presentations to take you beyond the program. We hope the details enhance your experience or provide you with more insight into the proceedings.
Development of the Northwestern University Flexible Sub-Ischial Vacuum (NU-FlexSIV) Socket for Persons with Transfemoral Amputation
Stefania Fatone, PhD, BPO (Hons); Ryan Caldwell, CP/L, FAAOP
This session will describe a teachable subischial socket technique that results in improved comfort and comparable function when compared to ischial containment sockets. Noting that lack of socket comfort is the most common complaint of prosthesis users and that soft tissues are not well suited to the high pressure and shear loading that occur during transfemoral prosthetic ambulation, the presenters will describe the technique they used in their socket technique to address these issues and improve the user’s comfort.
The socket includes a highly compressive, cylindrical, fabric-covered silicone liner; a flexible inner socket; and a shorter, rigid outer socket with vacuum applied between the liner and inner socket. The undersized liner and socket are used to compress the residual limb, stiffening the soft tissue and decreasing relative motion of the limb within the socket. The impression is taken over the liner with the patient seated and the limb flexed and slightly abducted, allowing gravity to premodify the tissues. The researchers used algorithm and rectification mapping to facilitate decisions related to socket fabrication. Socket comfort score, 11 gait analyses, and clinical outcome measures were used to assess the socket performance in comparison to an ischial socket. Clinical experience fitting the socket confirms these research findings.
Walking Performance, Endurance, and Perceived Exertion in People With Transtibial Amputation: Effects of a Modified Running-Specific Foot
Brian J. Hafner, PhD; S. J. Morgan; C. M. McDonald; P. A. Kramer; and G. E. Davidson
This session will discuss the methods and results of a pilot study undertaken to compare walking performance, endurance, and perceived exertion between a modified running-specific foot and a conventional energy storing foot. Transtibial amputation is associated with decreased walking speeds, diminished endurance, and increased metabolic demands. Energy storing feet are often prescribed to address these deficits, but may not mitigate the increased energy required for walking. Running-specific feet, however, enable runners with transtibial amputations to achieve endurance similar to runners without amputations. The length, curvature, and stiffness of a running-specific foot’s keel promotes running, but lack of a heel prevents heel-toe walking.
The session presenters will discuss a modified running-specific foot, which combines features of energy storing feet and running-specific feet, that was developed for walking, running, and other daily activities. It includes an extended carbon keel attached directly to the socket, heel springs to facilitate heel-toe walking, and a shell that fits typical shoes. Initial modified running-specific foot user feedback has been positive, but evidence is needed to support prescription.
Data collected in the study was used to power a prospective, randomized crossover study of participants with transtibial amputations, which was funded by the U.S. Department of Defense. Data collection is ongoing and available results will also be shared.
Functional Socket Design for Hip Prosthetics
Marlo Ortiz, CP(M)
In this session, Ortiz will describe a study conducted of a hip disarticulation prosthesis that includes an ipsilateral flexible inner socket and abbreviated carbon fiber frame, combined with a flexible thermoplastic contralateral pelvic plate. The socket emphasizes intimate and extensive full encapsulation of the ischial-ramal complex, encapsulating the ramus in four dimensions. The socket design also has close anatomical contouring and lower proximal trim lines to provide a full range of motion.
A typical problem with hip disarticulation prostheses is the ischial weight bearing, requiring the use of soft materials at the bottom of the socket for cushioning, which moves the pelvis partially out of the socket, diminishing the user’s control. Ortiz will discuss a method in which the pelvis can be locked inside the socket, completely encapsulating the ischial-ramal complex, which increases prosthetic control, minimizes pressure in the ischium, and lifts soft tissues. A containment shell, made of flexible thermoplastic material in a carbon fiber frame, removes the need for padding material in the ischial-ramal area. Ortiz will discuss the methods used to improve suspension, rotational control, and gait patterns. In most of the cases in Ortiz’s study, there was no vaulting when patients walk, and lateral shift of pelvis is improved.
Keynote Speech: Cosmetic Socket Technology
Marlo Ortiz, CP(M)
The main objective of the transfemoral M.A.S. socket, developed by Ortiz in 1999, was to provide more ischial-ramal containment, thereby giving the user more control over the prosthesis. It also improved range of motion, socket comfort, and cosmesis. Ortiz will describe how experience with the technology and further research led to refinements that make better use of the residual muscles, allowing them to contract more efficiently. These modifications allow the user to better control the prosthesis and walk using less energy, thus letting him or her walk for longer periods at a strong pace.
The presentation will include the details of the M.A.S. updates, the muscular lock, and cases that portray the improvements and benefits.
Osseointegration and Implanted Neuromuscular Interfaces for Prosthetic Control
Max Ortiz Catalan, PhD
This session will focus on clinical outcomes of current treatments for phantom limb pain and the results of a clinical trial of Ortiz Catalan’s approach to such treatments, which include augmented/virtual reality, gaming, and myoelectric pattern recognition. The session will also include a discussion of his work in which electrodes were permanently implanted in the nerves and muscles of an amputee’s residual limb to allow direct control of an osseointegrated prosthetic arm.
His method for treating phantom limb pain is based on the promotion of phantom limb movements with virtual and augmented reality. Complex movements of the phantom limb are predicted by machine learning algorithms using patterns of myoelectric pattern recognition, while the patient is provided with timely visual feedback in virtual or augmented reality environments.
His work has received worldwide media attention, including in The O&P Edge: “Muscle- and Nerve-Controlled Prosthetic Arm Unveiled,” “Myoelectric Signals, VR Ease Phantom Limb Pain,” and “Mind-Controlled Prosthetic Arm Reaches One-Year+ Milestone.”
