9
What we collect with this tool is therefore a datum
that finds meaning only in the context of a more
complete examination of the locomotor system.
5
05005
–
DELTA LEG N
5.1
INTENDED USE AND DESCRIPTION
Manual instrument suitable for measuring the heterometry
of the lower limbs in discharge, for the supine patient.
5.2
MATERIALS
Plastic, PMMA.
5.3
PACKAGE CONTENT
Body delta leg N, 1pc
Left footboard, 1 pc
Footboard right foot, 1pc
5.4
ADDITIONAL INFORMATION
A few considerations on lower limb heterometry:
As the term indicates, by heterometry, we mean a
difference in length of the lower limbs, whatever the cause;
with the same meaning, we can find various terms:
disparity, discrepancy, unequal length; they are all
essentially synonyms.
However, it is a good idea to avoid the term “dysmetria”,
occasionally used by some authors, because it is used with
a completely different meaning in the neurological field.
In Anglo-Saxson literature, heterometry is usually indicated
by the
expression “leg length discrepancy
-
LLD”.
What does heterometry come from?
There are two distinct categories:
a) anatomical or structural heterometry - is an effective
difference in the length of the skeletal segments (due to
congenital or acquired causes);
b) functional heterometry - when the difference is tied to
muscular contractures, axial deviations, subluxations,
articular lassitude, asymmetry of the pelvis, etc.; factors
that when present in the limb, determine an apparent
shortening of it.
When is a heterometry important?
Scientific literature isn’t in agreement on what value of
heterometry is to be considere clinically revelant. For
some authors, 5 mm are already significant while for
others, 2 cm can be unimportant.
Generally, they are personal opinions based on
anecdotal observations.
At the root of these uncertainties is first of all the
indeterminateness of the clinical measure, tied to the
ample error margin associated with evaluation methods
that have been available up to now.
Methods for evaluating heterometry that are available to
date
1.
X-
ray examination: this represents the “gold
-
standard” and
is essential for programming a surgical operation in the
clinicallyrelevant forms.
On the other hand, it presents obvious limitations of use tied
to radiological risk and therefore is usually not used for the
more modest forms, which are also the most common.
2.
Methods of clinical observation (commonly used in
specialized outpatient departments and in gymnasiums):
a) tape measure method: using a tape measure, different
anatomical references can be used:
- SIAS - internal malleolus
- SIAS - external malleolus
- Navel - internal malleolus
Whit these measurements, the error (evaluated by
repeating the measurement various times by the same
observer or by two different observers) can exceed one
centimeter and in some controlled studies, differences
greater than 2 cm have been unacknowledged.
b) Evaluation in upright posture while observing the height
of the:
- iliac crest
- upper, anterior iliac spines
- sacral recesses
With these methods, the difference can be “estimated” or
calculated by placing lifts until achieving compensation
(checked with a level).
These methods too - although used at length - have ample
uncertainty and only rarely have been subjected to
checking the error range linked with every measuring
procedure.
From these brief considerations, the fact emerges that with
the common clinical evaluation methods, heterometry of
0,5 cm cannot be evaluated and even an apparent
difference of 1 cm is to be cautiously evaluated before
making even a simple clinical decision such as adopting a
lift.
To obviate the evaluation limits available, a product has
been ideated: the DeltaLeg. It is a manual, non-invasive
instrument suited to value draining lower limb heterometry.
It is made of a bar on which two orthogonal platforms are
applied: one is fixed and acts as a reference while the
second is mobile along the longitudinal axis of the bar and
is equipped with a pointer.
The pointer indicates the positive or negative numerical
value of the heterometry on a millimetric scale located on
the upper surface of
the bar. The value “zero” corresponds
to the reference platform
