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160 HIGHSMITH ET AL.

foot, which utilized a carbon fiber keel and ankle; study compared VO2 peak attained during running
and a running-specific ESAR foot, which utilized a for two TFA runners utilizing both a conventional
carbon fiber C-shaped keel but was heelless. During running prosthesis with an articulating knee mech-
walking for TFA, at both fixed speeds and self-selected anism and a prosthesis that had a non-articulating
walking speeds (SSWS), no significant differences knee joint (3). Results were mixed in that VO2 peak
were observed for energy costs (VO2, gait economy, was higher for one subject using the prosthesis with
gait efficiency (GE)) among the three prosthetic an articulating knee mechanism and one subject using
feet conditions. However, at SSWS, TFA patients the prosthesis that had the non-articulating knee
demonstrated significantly improved speed with the joint. However, both subjects were able to run longer
general-purpose ESAR foot and running-specific and attained faster speeds using the prosthesis that
ESAR foot compared to the SACH foot (7% and 9% had the non-articulating knee joint. Based on their
respectively). results, these researchers suggested that a prosthe-
Studies reporting the effects of prosthetic foot sis with a non-articulating knee joint may be more
components on energy costs and ambulatory per- energy efficient for TFA runners. However, this study
formance for TFA patients during running are very had several limitations. It utilized only two subjects,
limited. In their study, Mengelkoch et al. (2) reported did not specify an accommodation period for TFA
that TFA patients were not safely able to utilize the patients to utilize each type of prosthesis, performed
SACH foot during running. They observed that TFA the maximal exercise tests for both prostheses with
participants were able to run at speeds up to their only a 30 min rest between tests, and did not include
self-selected running speeds (SSRS) using the gen- information concerning ratings of perceived exertion
eral purpose ESAR foot and the running-specific during testing or subjective preference for running
ESAR foot. At SSRS, the speed deemed comfort- with each type of running prosthesis.
able for sustained distance running, GE was similar Given the limitations in the study by Wening et al.
for TFA subjects using the general-purpose ESAR (3), the purpose of this study was to further examine
foot and the running-specific ESAR foot. However, potential bioenergetic differences for TFA patients
a functional difference was that SSRS was signifi- utilizing a conventional running prosthesis with an
cantly slower using the general-purpose ESAR foot articulating knee mechanism versus a running pros-
(13%) compared to the running-specific ESAR foot. thesis that has a non-articulating knee joint.
Another important observation from this study was
that TFA participants were only able to run at speeds METHODS
greater than SSRS using the running-specific ESAR
foot. These researchers recommended that clinicians Subjects
should recommend and prescribe a running-specific Two male and two female (n = 4) unilateral TFA
ESAR foot for TFA runners interested in performing runners with amputation due to non-vascular causes
more vigorous distance-type running (i.e., for exercise were recruited (Table 1). Participants were healthy
and running competition). recreational runners (K4, Medicare Functional Clas-
It has been observed that some TFA distance sification Level), age ≤45 years, who performed run
-1
-1
runners prefer to run with a prosthesis that has a training 3 to 5 d·week for ≤30 min·d for ≥1 year.
non-articulating knee joint (i.e., a no-knee condition, The study was conducted in accordance with ethical
in which a straight pylon attaches to the prosthetic standards recommended by the Belmont Report (4).
socket and foot components). Anecdotally, it has The study protocol was approved by the University of
been suggested that, during running, increased South Florida’s Institutional Review Board, and each
energy may be required for TFA patients to control study participant provided written informed consent.
the prosthetic articulating knee to prevent it from
buckling, compared to a prosthesis with a non-ar-
ticulating knee joint (3). Previously, a preliminary