The difference between the measured lengths of the long and
short legs.
Apparent length
The length of the leg a s measured form the umbilicus to the
medial malleolus.
Blocks
In assessing patients with leg length
discrepancy it is important to have available blocks of calibrated thickness.
These can be placed under the heel of the short leg to simulate the effect
of corrective treatment.
Computerized tomography
A radiological technique in which
a spectrum of x-ray views is analyzed mathematically to produce a three
dimensional representation. It can be used to measure leg length discrepancy.
Epiphysiodesis
A surgical procedure which results in the arrest of growth
in a physis.
Functional leg length discrepancy
An asymmetry which makes the patient with equal leg lengths
function as if a leg length discrepancy were present.
Growth inhibition
The percent slowing of the growth of the short leg compared
to the long. It is calculated by determining the amount of growth of both
legs over the same period of time, calculating the difference, and dividing
the result by the growth of the long leg.
Growth rate
This term is used in a somewhat unusual way by Pedipod/LLD.
'Rate' usually is expressed with respect to time, but Pedipod/LLD, except
when using the Menelaus method, ignores the passage of time and considers
only skeletal maturity. Since skeletal maturity is so difficult to measure
accurately, this concept is only valid when comparing the 'rate' of one
leg to that of the other.
Magnification
In the context of leg length measurement magnification occurs
in radiological techniques in which the x-ray beams passing through the
measurement points are divergent. This results in the absolute measurement
on the x-ray being greater than that in the limb.
Maturity
In the context of leg length discrepancy maturity is the state
reached when the growth plates of the tibia and femur have closed.
Normal growth rate
The normal growth rate of the long leg is assumed to be the
rate determined from all data gathered before the first operative procedure
on that leg.
Orthoroentgenogram
A radiological technique for measuring the lengths of the
legs. In this technique a radiopaque ruler is placed on the table and
the hips, knees and ankles are exposed separately on a 14 X 34 inch film
Pelvic Obliquity (1)
The difference in the heights of the two iliac crests, expressed
in centimeters, with the patient standing with the knees extended, the
legs together, and weight on both heels.
Pelvic Obliquity (2)
The angle between the longitudinal axis of the trunk and the
perpendicular to the transverse axis of the pelvis.
Pelvic Obliquity (3)
The angle between the top surface of L5 and the transverse
axis of the pelvis.
Real length
The length of the leg as measured from the anterior superior
iliac spine to the medial malleolus.
Regression coefficient
A number which expresses how closely the relationship between
two sets of data can be described by a straight line. The regression coefficient
for data which is perfectly linear is 1.
Scanogram
A radiological technique for measuring the lengths of the
legs. This technique is similar to the orthoroentgenogram except the film
is moved beneath the patient between exposures so that the exposures of
the hips, knees and ankles all appear on one 14 X 17 inch film.
Scout film
A preliminary lateral view use in computerized tomography
to position the transverse sections. The CT software can be used to measure
true distances on this view.
Skeletal age
An estimate of chronological age based on the x-ray appearance
of the skeleton. In the context of leg length discrepancy it is an estimate
of the patient's stage of maturation.
Straight Line Graph
A special graph originally designed as part of a graphic method
for representing growth data in a manner to facilitate analysis and prediction.
Its principle feature is that the growth lines of the legs can be represented
as straight lines.
Swing phase
The phase of gait beginning with toe off and ending with foot
strike.
Teleoroentgenogram
A radiologic technique for visualization of the legs which
can be used for leg length measurement. It is a single antero-posterior
exposure of the legs on a 14 X 34 inch film with a 72 inch tube to film
distance.