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ARCOMETER D’OSUALDO
7.1
INTENDED USE AND DESCRIPTION
Measurement of the curves of the spine on the sagittal
plane (kyphosis and lordosis).
7.2
MATERIALS
PMMA, PE.
7.3
PACKAGE CONTENT
Arcometer, 1pc
Addiotional arm, 1pc
Cobb angles table, 1pc
7.4
ADDITIONAL INFORMATION
Dorsal kyphosis is a physiological curve, with a not-well
defined normality range; moreover we do not have clear
cut end points to identify its beginning and its end.
(Boseker EH e al, J Pediatric Orthopaedics, 2000; Wenger DR, Frick
S, Spine, 1999).
In the clinical practice an upper limit of normality for kyphos
between 40° and 45° is usually accepted.
Lordosis normality values are even more vague, nor there is
an agreement as what end vertebrae regards (e.g. lower
limit of L5 or upper limit of S1).
(VAL: agreement concerning the end vertebrae to
consider).
A normal subject continously modifies its kyphosis and
lordosis as consequence of postural adjustements.
Kyphosis can be described by two values only:
• The angle comprised under the
curve (Cobb angle).
• The radius of the circumference.
Current evaluation of kyphosis and lordosis relies on
radiographs
On a radiograph taken in upright posture (usually arms
forward), in a side projection, Cobb angle can be
measured (end vertebrae D1-D12; L1-L5) with the same
procedure usually adopted for scoliosis.
In order to avoid excessive exposure to X-rays, radiographs
should be taken only if strictly necessary; as consequence
they cannot be requested in every clinical evaluation or to
verify the efficacy of a brace or the action of exercises.
Tecnique to build Cobb angle
Error connected with the
measurement of Cobb angle on
radiographs.
It is usually accepted a reading
error between 3°-5° (up to 10° in
congenital scoliosis)
It depends on:
- the experience of the
examinator;
- the quality of radiographs;
- the amount of the curve;
- the avalability of tecnologicol
devices.
(Shea K.G. et al 1998).
The measurement of Cobb angle on radiographs can
be quicker and more precise by using an inclinometer.
- Whittle MW, Evans M: Instrument for measuring the Cobb angle in
scoliosis. The Lancet, 1979, Feb: 414).
-
D’Osualdo F., Schierano S., Iannis M; The levelprotractor, a new
simple instrument to measure back hump and Cobb angle; Eur
Med
Phys 2000; 36:191-196.
On the same curve, Cobb angle varies with the lenght of
the arch, radius value does not.
Starting from the end of the XIX century several instruments,
to measure kyphosis from the surface, have appeared in
scientific literature; among them we can quote:
1
Neugebauer device;
2
Debrunner kyphometer;
