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Improvement in Functional Outcomes with the Infinite Socket

Isaacson, Brad M., PhD, MBA, MSF; Lin, Stephanie C., MD; Rothberg, David L., MD

JPO: Journal of Prosthetics and Orthotics: October 2018 - Volume 30 - Issue 4 - p 181–186
doi: 10.1097/JPO.0000000000000210

Introduction The prosthetic socket, which provides an important patient interface for weight bearing and mobility, cannot adequately account for the dynamics of the residual limb, and problems with pain, skin breakdown, verrucous hyperplasia, and bursitis are frequent. To address these issues, LIM Innovations, a prosthetics manufacturer, has developed the Infinite Socket, an adjustable, custom-molded modular socket made of a carbon fiber frame and a two-part tensioning system that can be adjusted by the user.

Materials and Methods Patients with transtibial or transfemoral amputations were asked to participate in this study between the period of June 30, 2015, and January 1, 2017, if they had a standard-of-care thermoplastic socket and were dissatisfied. Patients were fit with an Infinite Socket, and functional outcome tests were performed at the time of the Infinite Socket fitting. It was hypothesized that the Infinite Socket would improve functional outcomes compared with the subjects' legacy prosthetic sockets.

Results One hundred twenty-seven patients with limb loss (18 transtibial and 109 transfemoral) participated in this study. The mean age of participants was 48 years (range, 19–82) and 82% were male. Data indicate that the Infinite Socket had superior outcomes compared with legacy standard-of-care prosthetic sockets for socket comfort scores (7.64 ± 2.00 vs. 4.52 ± 2.22, P < 0.0001), 2-minute walk test (108.80 ± 31.28 vs. 101.53 ± 33.96, P = 0.007), and the Four-Step Square Test (17.01 ± 12.14 vs. 21.57 ± 18.52, P = 0.005). There was no statistically significant difference in the L Test (30.98 ± 27.51, 36.31 ± 45.64, P = 0.246).

Conclusions A new modular, patient-adjustable prosthetic socket demonstrated improved functional outcomes compared with the legacy standard-of-care prosthetic socket. Participants reported higher socket comfort scores and mobility scores were improved for the two-minute walk test and Four-Step Square Test for those using the Infinite Socket.

BRAD M. ISAACSON, PhD, MBA, MSF, is affiliated with the Center for Rehabilitation Sciences Research, Department of Physical Medicine and Rehabilitation, Uniformed Services University of Health Sciences, Bethesda, Maryland.

BRAD M. ISAACSON, PhD, MBA, MSF, is affiliated with The Geneva Foundation, Tacoma, Washington.

STEPHANIE C. LIN, MD, is affiliated with the Sutter Health, San Francisco, California.

DAVID L. ROTHBERG, MD, is affiliated with the Department of Orthopedics, University of Utah, Salt Lake City, Utah.

Disclosure: The authors declare no conflict of interest.

Disclaimer: The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army, the Department of Defense, or the US government.

Correspondence to: Brad M. Isaacson, PhD, MBA, MSF, The Geneva Foundation, 917 Pacific Ave, Tacoma, WA 98402; email:

© 2018 by the American Academy of Orthotists and Prosthetists.