Follow the Science

Supported by Clinical Evidence


Featured Research:
In a Blatchford PEQ Study, Px Satisfaction increased an average of 109.4% with HiFi, with all other categories also improving.

Our HiFi Interface and Imager™ system, with patented and patents-pending technology, is the most advanced design available because we focus on body biomechanics, responsiveness, pressure, bone positioning, tissue management, efficiency of movement, gait symmetry, range of motion, proprioception, energy savings, and overall user embodiment, all while ensuring superior comfort. 
We know the attachment platform is the core factor in determining success or failure of attached devices and is in direct proportion to wear times, walking speeds, balance confidence, falls, comfort, and overall function. Components today are highly effective and functional, yet they are being attached to inefficient socket platforms.  Time to follow the science. Time to Demand HiFi. 

Yearly fall rates. 

Did you know, falling and the fear of falling is prevalent among the amputee population, especially for AK amputees?

A significant factor in these falls is an unstable socket that allows too much bone movement inside. Our HiFi Interface, also referred to as Compression Release Stabilized or CRS, is based on judicious application of our OsseostabilizationTM principles which results in a synching of the interface and its attached components to skeletal motion, an effect dubbed Osseosynchronization.™
The HiFi Interface platform is based on proven biomechanical principles, backed by clinical evidence, and has been used successfully in prosthetic practices for nearly a decade, with thousands of patients fit. The HiFi technology was also utilized in two DARPA and two VA studies, as well as a SBIR Phase I U.S. Army Exoskeleton contract.
The HiFi has shown promise far beyond traditional outcome measures and is embarking on the phenomenon of embodiment. Many wearers report lost phantom sensations returning to their limb, allowing them to feel the ground and prevent falls.
“The HiFi makes me feel more secure and makes mobility easier. It is less and lighter – but I can get more out of it. It feels more like a part of me. It moves with me. I’m not fighting it. There is not as much effort to get the movement I’m looking for. This is the feeling I’ve been looking for. It’s the anatomical extension of my limb.” – Jeff Fabry, 2012 Paralympic gold medalist, archery
Sound side overuse, breakdown and Osteoarthritis (OA) are common problems. If you don’t trust your prosthesis, you will compensate with your sound side. Initial research shows the HiFi Interface improves gait symmetry and balance confidence, among other benefits. Imagine an interface that can help save your sound side from further breakdown, improving your overall quality of life.

HiFi Interface Theory and Biomechanics

Randall Alley, et al published a journal article describing the theory and superior biomechanics of the HiFi design for upper and lower limb amputees. The HiFi’s patented and patents-pending compression and tissue release technology reduces unwanted motion of the bone within the interface and increases socket stability, while increasing the wearer’s capability to handle greater loads.  Journal of Rehabilitation Research and Development, 48(6), pp. 679-696, “Prosthetic Sockets Stabilized by Alternating Areas of Tissue Compression and Release.”

Subischial HiFi vs. IRC Socket - X-Ray Comparison Shows Improved Femur Control

X-ray visualization of Subischial HiFi Osseostabilized Interface shows improved control of femur and reduced lag when moving the prosthesis vs. Ischial Ramus Containment (IRC) socket. Also noted is lower trim lines in the HiFi.
A preliminary study was performed at biodesigns using x-rays to visualize the bone position relative to the socket in both an ischial ramus containment socket and a HiFi Interface. When the patient stood equally weighted in a comfortable stance, the femur was found to be abducted and positioned laterally within the soft tissue in the IRC socket, whereas in a HiFi Interface the femur is centered within the soft tissue and lies more naturally in adduction. The x-ray analysis of the patient with his prosthetic side hip flexed to 90 degrees and unsupported while wearing the prosthesis shows very little skeletal motion is lost in the translation and movement of the prosthesis while wearing the HiFi Interface. A greater discrepancy was found between the angle of the femur relative to the angle of the socket using an IRC socket. The HiFi’s claims of skeletal control, stabilization, and synchronization were imaged and confirmed. Patients have noted that with greater control they require less effort to move their prosthesis, saving them energy with every step.

Subischial HiFi Suction Socket vs. Elevated Vacuum - Gait Comparison Shows Reduced Gait Variability

Using a BTS G-Walk system, step variability (or the level of differentiation of the same side step as compared to its predecessors and successors) was compared between a subischial HiFi Interface with an expulsion valve and a subischial elevated vacuum socket. Graphical analysis showed that the HiFi Interface had a significantly reduced step variability and allowed for a more even, natural gait.

Subischial HiFi vs. IRC Socket - Biomechanics Comparison, Eastern Michigan University

EMU study documents that HiFi Interface improves stability, symmetry, and function, while decreasing pain, fatigue, fall risk, and self-reported disability.
This study was conducted with IRB oversight under the direction of Professor Jeff Ropp, BSc, CP and Tyler Klenow, MSOP, CPO, CPT and included self-report standardized clinical outcome measures and gait analysis conducted with a Vicon Motion Capture System. The study concluded the HiFi Interface increased stability which further resulted in decreased pain, fatigue, and marked increases in function. Gains were seen in both self-selected walking velocity and overall gait symmetry between the prosthetic and sound sides with the HiFi Interface. Center of mass deviations decreased vertically and laterally with the HiFi Interface, which correlates to greater stability during ambulation and reduced fall risk. In subjective measures, the patient improved from a category of Severe to Moderate in amputation-related disability per the Oswestry Questionnaire and reported a nearly 20% increase in functional ease per the Western Ontario and McMaster University Osteoarthritis Index (WOMAC). The Journal of Prosthetics and Orthotics, 29(3), pp. 130-136,  “Comparative Efficiency of Transfemoral Prosthetic Interfaces.”

Subischial HiFi vs. IRC Socket - PEQ Study, Blatchford-Endolite Study

Blatchford’s UK study at Crystal Palace and Charing Cross facilities had amputees pre and post bring fit with HiFi, complete Prosthesis Evaluation Questionnaires (PEQ). Results showed improvements of 20-110% in functional and subjective measures. With the HiFi Interface patients reported an average improvement of 48.6% in ambulation, 49.8% in utility, 19.0% in transfers, 74.9% in well-being, 109.4% in prosthesis satisfaction, and 90.9% in walking satisfaction.  Subjects also noted that they had increased sitting comfort with the subischial HiFi Interface, a general feeling of being more connected to the knee joint and componentry, and greater proprioception transmitted through the prosthesis.

Subischial HiFi vs. IRC Socket - PT Case Study, California State University Northridge

PT Case Study documented HiFi Interface provides greater comfort, stability, function, quality of life and significant improvement in fall risk. Additionally, the subject’s activity level improved from a K2 to a K3 while wearing a HiFi Interface as determined by the Amputee Mobility Predictor (AMP).
At California State University Northridge, Physical Therapist Victoria Graham completed examinations pre and post HiFi fitting. Subjective reports using the Socket Comfort Scale (SCS), Activities Balance Confidence Scale (ABC), Prosthesis Evaluation Questionnaire (PEQ), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) showed the subject reported significantly greater comfort, stability, perceived function, and quality of life with the HiFi Interface. The ABC indicated improvement of over 60%, which put the user within 1 pt. of the fall risk threshold when using the HiFi Interface. Functional measures saw improvements of 20-50% across tests such as the Four Square Step Test, Timed Up and Go, (TUG) L-Test, and Amputee Mobility Predictor (AMP). The AMP tested noted the subject’s activity level improved from a K2 using a traditional socket to a K3 while wearing the subischial HiFi Interface.

Subischial HiFi vs. IRC Socket - Gait Speed, Fall Risk

Summary: Data generated by Sampson et al and analyzed by Kahle et al concluded the HiFi Interface significantly outperformed IRC sockets in objective and subjective tests employed in study. Notable findings revealed that the HiFi interface allowed wearers to walk faster, farther, and with greater balance and energy savings.
Bill Sampson, Sampson Prosthetics and Orthotics, engaged a physical therapist to study and report on the comparative effects of subischial HiFi interface to ischial ramus containment (IRC) sockets. Components were kept consistent with the only variable being the interface design. The data was analyzed and it was concluded that the HiFi interface significantly outperformed IRC sockets in objective and subjective tests. While using the HiFi interface increased walking capability was observed in terms of being able to walk faster, farther, and with greater energy savings. Increased balance confidence was also observed as users in the HiFi interface reported less falls and greater stability. Additionally, the lower trim lines offered in the subischial HiFi interface provided greater levels of comfort and range of motion. The results were published in Technology & Innovation, 18(2) pp. 167-173, “The Effects of Transfemoral Interface Design on Gait Speed and Risk of Falls.”

Femur Bone Control in Water - Therapy Case Report

HiFi Authorized Provider Tom Cutler, CPO, reported on his case study of a patient rehabilitating through aquatic ambulation while utilizing the HiFi interface. The study indicated that the HiFi Interface has significant control of the femur and concluded improved rehabilitation of the patient can be accomplished with the combination of a HiFi Interface and aquatic therapy. This case study can be found in the Journal of Prosthetics and Orthotics, 29(4), pp. 206-212, “Rehabilitation of an Individual with Transfemoral Amputation Combining Aquatic Ambulation with Prosthetic Socket Incorporating High-Fidelity Skeletal Capture: Case Report.” 

Transhumeral HiFi vs. Traditional Socket - Stability Study, VA

After numerous fittings of the CRS/HiFi Interface paired with the DARPA/DEKA LUKE Arm, Linda Resnick, principal investigator, reported that the HiFi Interface provided better control of the residual limb within the socket and had less slippage when compared to traditional designs. The results of this study can be found in Disability and Rehabilitation: Assistive Technology, pp.1-10, Comparison of Transhumeral Socket Designs Utilizing Patient Assessment and in-vivo Skeletal and Socket Motion Tracking: a Case Study.”

Subischial HiFi vs. IRC Socket - Pistoning Study, Blatchford-Endolite

Saeed Zahedi, Technical Director at Blatchford Endolite, performed a comparison between IRC sockets and HiFi Interfaces. The study showed the HiFi Interface reduced pistoning by 50%. Study results were presented in the Royal Overseas League, “London Shear Force in External Limb Prosthetics.”

Transradial Biomechanical Design Considerations for Improved Efficiency and Safety

Sang et al, stated that biomechanics can help determine better efficiency and safety for interface designs, and that force and motion transferred together with comfort and safety are two main aspects of prosthetic interface designs. Sang concluded load distribution and transmission should rely on achieving skeletal control through targeted soft tissue relief, which is a core design principle of the HiFi Interface. The article was published in the Journal of Engineering Medicine, 230(3), pp. 239-250, “Biomechanical Design Considerations for transradial prosthetic Interface: A Review.” 

Subischial Vacuum vs. IRC Socket - Comfort Comparison

Jason Kahle, researcher, compared Ischial Ramus Containment (IRC) sockets to Vacuum-Assisted Suspension (VAS) and determined that except for medical proximal pressure, no other measures reached statistical evidence. However, all subjects preferred subischial sockets. The HiFi Interface is the only socket design that has the needed stability that allows it to be subischial with or without vacuum. Thus patient preferences for subischial are met with the HiFi and would likely lead patients toward a greater acceptance of HiFi versus traditional socket designs. The Journal of Rehabilitation Research and Development, 50(9), pp. 1241-1252, “Transfemoral Sockets with Vacuum-assisted suspension comparison of hip kinematics, socket position, contact pressure, and preference: ischial containment versus brimless.”
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HiFi Transhumeral Interface vs. SOC Humeral Socket - Ultrasonic study

Single case study that looked at displacement of the bone in a HiFi Humeral Interface and a Standard of Care (SOC) socket using ultrasound. Study showed the HiFi Interface outperformed the SOC socket in terms of controlling the bone, exhibiting significantly less skeletal translation.

The Effect of Socket Tightness in Femur Stability in a HiFi Socket - Department of PT, School of Medicine & Health Sciences, University of North Dakota

Authors: Mary Bachman, BS, University of North Dakota, Alicia Beckel, AA, Rainy River Community College, Amanda Belyaks, BS, University of North Dakota, in their study found that increased tightness of the HiFi socket did result in less movement between markers and decreased lifting of the leg to compensate for a loser socket resulting in better biomechanics. This suggests that increased stability and tightness of the socket around the femur are advantageous provided by the HiFi socket to improve gait mechanics and requires less compensation than a loser fitted socket, but further research is needed.

Bam! HiFi is validated.

Don’t let anyone hold you back.