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. 2022 May 2;4(3):100200.
doi: 10.1016/j.arrct.2022.100200. eCollection 2022 Sep.

A Prospective Assessment of an Adjustable, Immediate Fit, Subischial Transfemoral Prosthesis

Timothy R Dillingham  1 , Jessica L Kenia  1 , Frances S Shofer  2 , James S Marschalek  3
Affiliations

A Prospective Assessment of an Adjustable, Immediate Fit, Subischial Transfemoral Prosthesis

Timothy R Dillingham et al. Arch Rehabil Res Clin Transl. .

Abstract

Objective: To assess the feasibility of an adjustable, subischial transfemoral prosthesis by comparing self-reported outcome measures regarding socket comfort, fit and utility relative to a persons' conventionally made socket. Assessing limb compressibility was another aim of this study.

Design: A single-group pre-post intervention design.

Setting: Physical medicine and rehabilitation biomechanics laboratory.

Participants: All 18 enrolled participants (N = 18) completed the feasibility trial. There were 16 men and 2 women with an average age of 59.4 (±7) years. Most of the participants (61.1%) had worn a socket for 1 to 10 years before the trial, 22.2% of the participants had worn one for less than a year, and 16.7% of the participants had worn a prosthesis for more than 10 years.

Intervention: Participants were fit with the study prosthesis and used it for a 2-week home trial.

Main outcome measures: A Prosthetic Comfort and Utility Questionnaire was completed on the participant's conventional prosthetic device and the subischial socket system after the trial.

Results: The adjustable subischial prostheses were rated superior overall to the participant's conventional sockets (40.9 ± 7.2 vs 32.8 ± 10.8; P=.004). Six of the 10 parameters measured (adjustability, overall fit, prosthesis weight, sitting comfort, standing comfort, and standing stability) were rated higher for the adjustable prostheses compared to the conventional sockets. Compression of the soft tissues of the thigh ranged from 5.6 ± 4.2 cm at the distal end to 7.3 ± 3.6 cm at the proximal site. There were no falls, skin breakdown, or limb ischemia. At the 2-month telephone follow-up, 61% of subjects had transitioned to using the adjustable subischial socket most of the time.

Conclusions: The adjustable, immediate fit, subischial prosthesis provided safe, comfortable, and functional ambulation for persons with transfemoral limb loss in this short-term feasibility study. This study supports the consideration of a new paradigm in transfemoral prosthetics-adjustable subischial sockets. These devices should be tested in a larger multi-center study.

Keywords: Adjustable prosthesis; Amputation; Limb loss; PCUQ, Prosthetic Comfort and Utility Questionnaire; PEQ, Prosthetic Evaluation Questionnaire; Prosthetic; Transfemoral amputation; Transfemoral prosthesis.

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Figures

Fig 1
Fig 1
The locking buckle system for closure of the subischial socket. The buckles (situated on the lateral leg) and hooks (placed on the medial leg) close the adjustable socket securely around the limb.
Fig 2
Fig 2
The adjustable subischial transfemoral prosthesis. Components: (1) locking buckle, (2) hook, (3) steel cable, (4) offset, (5) lateral rigid frame, (6) flexible/inner liner, (7) outer flap, and (8) cup.
Fig 3
Fig 3
Results of the Socket Comfort and Utility Questionnaire comparing conventional socket (own) and immediate fit socket (iFIT) after 2-week home trial. CI, confidence interval.
Fig 4
Fig 4
The subischial socket with its low profile on the leg, allowed this subject to comfortably ride a stationary bike.
See this image and copyright information in PMC

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