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GENIUM KNEE: MOBILITY & ECONOMIC OUTCOMES 147

resulting from Genium use. Beyond this, previous is desirable and yielded positive changes in function
tests of function in ADLs demonstrated improve- as previously noted in stair and multi-directional
ments in multi-directional stepping (4). Most notably, stepping function. Further supporting true change
rearward directed steps and small steps were improved is the fact that the AMP test also measured a signif-
(4,25). In a previous test involving moving laundry icant increase in functional level using parameters
from a washer to a dryer, a task involving small side other than step activity. While this was true for both
steps and rearward steps, significant improvements functional level measurements, neither functional
were observed (4), which are consistent with the 9% measure changed to a higher functional level. Instead,
improvement in 4SST times recorded in this study. subjects’ function increased significantly within their
Two means were used to assess functional level respective functional level. For instance, the group
in this study. One was the AMP test, a test of transi- did not change from limited community to unlimited
tional movement, stepping and balance (14) and the community ambulation.
second was a functional level based on step activity.
Tasks improved on the AMP test associated with ADL Survey and Preference
Genium use included stair gait, obstacle crossing, In addition to the objective functional measures
and variable cadence. Conversely, most subjects were described above, perceptive measures were increased
unable to achieve single-limb balance on the pros- or unchanged. Subjectively, there were no decreased
thesis regardless of which MPK they were using. The functional measures or decreased perceptions of
2.0 point increase observed with Genium use in this safety associated with use of the Genium. It is note-
study did not reach the minimal detectable change worthy that Genium increased safety and function in
(MDC) value of 3.4 points for the AMP reported areas requiring community engagement (e.g., family,
by Resnik and Borgia (28). Because the difference social and leisure roles, mobility and transportation)
in AMP scores did not reach the MDC, it could be because this is consistent with the type of subject
argued that true change may not have occurred rela- enrolled in the study who was (on average) in their
tive to this specific test. However, Resnik and Borgia’s mid-forties and active in the community. The fact that
sample was of mixed amputation level. Further, AMP there was no difference in self-care suggests C-Leg
scores were statistically significantly different, and may be meeting many of these needs. Conversely, the
key functions were improved with Genium use (e.g., lack of difference in exercise function could be that
stair gait, variable cadence, and obstacle crossing). both components still leave room for improvement.
Additional issues worthy of consideration include Interestingly, there was a significant difference in
the test’s use of interval level data and the wide range preference among this group of unlimited commu-
of task difficulty. nity ambulators. The magnitude of difference was
Previous study has shown that TFA patients tend comparable to that previously observed when a more
to not alter their usual living patterns and step activity functionally diverse subject group was asked their
based solely on receipt of a new knee system (29). preference between NMPKs and the C-Leg (15). It
However, in this study, there was a significant increase is unclear if preference would be so strong in more
in functional performance based on step activity. functionally diverse patient groups or patients more
These changes in activity took place while participants homogeneously located at higher or lower ends of
were in their community or home environments, as the functional spectrum.
lab steps were not counted. Thus, subjects had suffi-
ciently increased steps, steps/bout, or step intensity to Cost-Effectiveness
elevate their step activity derived functional levels. It In this study, using functional measures, the ICER
is possible that subjects took these additional steps or for reimbursing Genium vs. C-Leg ranged from $6,000
changed their stepping routine in part due to partici- to $6,522 per unit of functional increase assuming a
pation in the study while attempting to accommodate $30,000 intervention cost difference. Assuming the
with the study knee. From an activity perspective, this component would not require replacement for five