Stance Control Orthoses Do Not Significantly Reduce Energy Expenditure

ORLANDO, Fla. — Stance control orthoses (SCOs) improved walking
velocity in patients; however, the device may not affect overall energy
expenditure, according to a study by Priya Davis, BPO (Hons).

  Priya Davis
  Priya Davis

Davis presented these findings as part of the Thranhardt Lecture Series
at the
2011 Annual Meeting and Scientific Symposium of the American
Academy of Orthotists and Prosthetists

Gait deviations, like those experienced by patients with polio, increase
the mechanical work of walking, she said. Stance Control Orthoses (OCSs)
provide stability for these patients by locking during the stance phase of gait
and unlocking during the swing phase.

Davis, therefore, predicted that the SCOs would reduce energy
expenditure and increase walking velocity compared to a locked
KAFO, according to the study.

Where she practices in Australia, there are approximately 1,400 patients
who have polio and many would be suitable candidates for treatment with SCOs.
She tested 10 patients with the SCOs — making it the largest study sample
to date in this area.

When gathering information for this study, Davis found that there is
limited research describing the energy advantages of SCOs, and the results are
inconsistent across the studies.

Results showed that “knee flexion during swing phase in people with
significant lower limb pathology may not substantially reduce energy

Davis also found that the energy expenditure walking task may not be the
best indicator of a patient’s true gait. The test may more closely
resemble community ambulation where the subject must demonstrate walking in
front of an audience.

She noted that completing the same study with a different device would
produce varied results, and said that is an area for possible exploration in
the future. — by Stephanie Z. Pavlou


Greater uniformity of reporting by presenters and publishers of
information regarding orthosis/prosthesis design features would be quite
beneficial for audience members and readers in the clinical and scientific
community to better understand the wearable technology used by participants in
an investigation or other clinical outcome assessment. Because there are many
design features and components in orthoses and prostheses, and since there are
variations in interpretation of design features, it would be helpful if there
was greater uniformity in the format of presenting these features.

  Christopher Hovorka
  Christopher Hovorka

For example, a presenter or author could assist the audience in better
understanding a prosthesis used in an investigation or clinical case by
reporting design variables in a universal format — for example, basic
suspension system, residual limb interface or socket design, and category of
component parts attached to the prosthesis structure such as hip, knee,
ankle/foot system and alignment. For an orthosis, the presenter or author at
least could report the joint/body segment and fundamental biomechanical
alignment of targeted body structures encompassed within the orthosis and the
footwear, including general description of the rocker profile. Since the
aforementioned features are unique to prosthesis/orthosis designs and since
variability in these designs may influence the performance of the user of the
technology, it would be beneficial if the basic characteristics were reported
in a uniform format.

In Dr. Raya’s presentation, she reported a cohort of persons with
lower limb amputation and their functional performance variations when wearing
their prosthesis/prostheses. However, there was no information reported on the
features of the prosthesis/prostheses used by participants. Presenting features
of the suspension system, socket design, components and alignment may have
added to the context of her research outcome and may have stimulated additional
questions and discussion from the audience.

In Ms. Davis’s presentation, she reported on a cohort of persons
using lower limb orthoses designed to provide constraint of ankle and knee
motion. Since the orthosis-footwear combination is an important variable that
may influence the performance of a person during standing and walking —
regarding kinematics, kinetics, metabolic, etc. — the fact that there was
no mention of this feature was an oversight. Reporting that feature could have
implications in the performance of the participants and could have stimulated
further discussion and consideration from the audience in weighing her reported
research methods and outcome.

I am just encouraging the O&P community to be a little more specific
about the orthosis/prosthesis device design when presenters and authors share
their research and/or clinical outcomes.

A look at other more rigorous science areas reveals that there are
communities where the scientists and clinicians have gotten together and
decided on the variables and how they should be reported. One example is the
Surface Electromyography for the Non-Invasive Assessment of Muscles (SENIAM).
It is a European concerted action in the Biomedical Health and Research Program
of the European Union to standardize the reporting of neuromuscular function.
Because there is variety in methodology used, it hampers widespread use of the
technique; therefore standardization is essential. SENIAM thus formulated a
work group to standardize reporting of electromyography.

An orthosis or prosthesis could similarly be reported more uniformly in
order to ease the burden of interpretation by the audience or reader.

— Christopher Hovorka, CPO, FAAOP
Institute of Technology MSPO Program

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