Perometer (400T) Measurement of lower limb volume: development of a standardised protocol.
Author
Coutts, Fiona
Grainger, Andrew
Bulley, Catherine
Metadata
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Coutts, F., Grainger, A. & Bulley, C. () Perometer (400T) Measurement of lower limb volume: development of a standardised protocol., , , , ,
Abstract
PURPOSE: This abstract presents a standardised protocol for the
measurement of lower limb volume using the Perometer (400T)
and evaluation of its test-retest reliability. RELEVANCE: Changes
in limb volume result from a variety of musculoskeletal, vascular
and neurological conditions. Limb volume measurement is important
in monitoring treatment efficacy. Although the Perometer (400T)
optoelectronic imaging device can be used to assess limb volume, no
protocol has been published to standardise its use. DESCRIPTION:
A standardised protocol was developed through multiple pilot studies:
1) The individual to be measured is required to sit with their
lower limb elevated for five minutes to allow equilibration of tissue
fluid. Pilot work involving one individual compared rest periods of
5, 10 and 15 minutes. Lower limb volume reduced by 0.28%,
0.12% and 0.52% respectively; the maximum reduction of 26.67
mls is likely to be clinically negligible. 2) A standardised endpoint
for limb volume calculation is marked at 65% of femur length
measured from distal (inferior lateral condyle) to proximal (superior
greater trochanter). This proportion of limb length was selected
following pilot work with three male and three female participants
of different heights. 3) Normally the participant's foot is placed
in the middle of the Perometer base-plate. A cylinder of known
volume was placed in 16 segments outlined on the base-plate and
the most accurate volume estimates were achieved in the central
positions. 4) The normal stance for use with the Perometer (400T)
requires the individual to stand sideways to the vertical Perometer
track. Strict positioning of the lower limb in neutral rotation is
not necessary: measurements carried out at increasing degrees
of rotation from 0-60 degrees to both right and left demonstrated
low coefficients of variation (<0.6%). 5) The Perometer frame is
moved vertically up the lower limb to the standardised end-point
at an average speed. Pilot work demonstrated higher measurement
variability when the frame was moved rapidly compared to average
or slow translations, although the coefficient of variation remained
below 0.6%. 6) The distance from floor to standardised endpoint
on the lower limb is entered into the computer software to
calculate the volume of a standardised proportion of the lower
limb. EVALUATION: The finalised protocol was repeated nine times
on 30 participants by one investigator on two separate occasions.
Test-retest reliability was calculated using Limits of Agreement
(Bland & Altman, 1986), indicating that 95% of the time lower limb
volume calculations will vary between 159.2 mls and -181.04 mls,
amounting to 0.0004% variation and excellent test-retest agreement.
CONCLUSIONS: Adoption of this standardised protocol for the
Perometer (400T) will allow reliability of measurement in clinical
practice. Further development and evaluation are needed, including
investigation of defined speeds of Perometer frame movement, and
reliability and validity of the protocol in different clinical populations.
IMPLICATIONS: Standardised protocols are important to enable
comparison of data within and between individuals at different clinical
sites. This protocol for measuring lower limb volume using the
Perometer (400T) will facilitate ongoing multi-site audit and evaluatin
of management strategies.