Methods for Assessing Leg Length Discrepancy

Abstract

The use of accurate and reliable clinical and imaging modalities for quantifying leg-length discrepancy (LLD) is vital for planning appropriate treatment. While there are several methods for assessing LLD, we questioned how these compared. We therefore evaluated the reliability and accuracy of the different methods and explored the advantages and limitations of each method. Based on a systematic literature search, we identified 42 articles dealing with various assessment tools for measuring LLD. Clinical methods such as use of a tape measure and standing blocks were noted as useful screening tools, but not as accurate as imaging modalities. While several studies noted that the scanogram provided reliable measurements with minimal magnification, a full-length standing AP computed radiograph (teleoroentgenogram) is a more comprehensive assessment technique, with similar costs at less radiation exposure. We recommend use of a CT scanogram, especially the lateral scout view in patients with flexion deformities at the knee. Newer modalities such as MRI are promising but need further investigation before being routinely employed for assessment of LLD.
Level of Evidence: Level IV, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Full text

SYMPOSIUM: ADVANCES IN LIMB LENGTHENING AND RECONSTRUCTION
Methods for Assessing Leg Length Discrepancy
Sanjeev Sabharwal MD, Ajay Kumar MD
Published online: 4 October 2008
ÓThe Association of Bone and Joint Surgeons 2008
Abstract The use of accurate and reliable clinical and
imaging modalities for quantifying leg-length discrepancy
(LLD) is vital for planning appropriate treatment. While
there are several methods for assessing LLD, we ques-
tioned how these compared. We therefore evaluated the
reliability and accuracy of the different methods and
explored the advantages and limitations of each method.
Based on a systematic literature search, we identified 42
articles dealing with various assessment tools for measur-
ing LLD. Clinical methods such as use of a tape measure
and standing blocks were noted as useful screening tools,
but not as accurate as imaging modalities. While several
studies noted that the scanogram provided reliable mea-
surements with minimal magnification, a full-length
standing AP computed radiograph (teleoroentgenogram) is
a more comprehensive assessment technique, with similar
costs at less radiation exposure. We recommend use of a
CT scanogram, especially the lateral scout view in patients
with flexion deformities at the knee. Newer modalities such
as MRI are promising but need further investigation before
being routinely employed for assessment of LLD.
Level of Evidence: Level IV, diagnostic study. See the
Guidelines for Authors for a complete description of levels
of evidence.
Introduction
Inequality in leg length is commonly associated with
compensatory gait abnormalities and may lead to degen-
erative arthritis of the lower extremity and lumbar spine
[29,40]. Patients with leg-length discrepancy (LLD) can
also have angular and torsional deformities as well as soft
tissue contractures of the ipsilateral or contralateral
extremity that may influence their functional leg lengths.
For instance, flexion contractures around the knee and hip
can cause apparent shortening of the leg while abduction
contractures of the hip and equinus deformity of the ankle
tend to functionally lengthen the affected extremity.
Besides clinical evaluation, there are several imaging
modalities that have been described to quantify LLD. The
use of appropriate clinical methods and imaging modalities
for measuring the LLD is vital to properly treat a patient
with unequal leg lengths or related symptoms.
The currently available imaging modalities include plain
radiography, computed radiography, microdose digital
radiography, ultrasonography, CT, and MRI. Accuracy of a
technique is defined as the variation of the measurement
using the imaging method compared with the actual mea-
sure, whereas reliability of the technique is the variation
between observers and within a single observer in obtain-
ing measurements. One needs to consider the reliability,
accuracy, magnification, radiation dose, cost, need for
special equipment, convenience, and ability to image the
entire extremity when choosing the imaging technique for
assessing LLD. Despite many reports, there appears to be
no comprehensive review of the various clinical and
imaging modalities as the subject of a single manuscript.
The purpose of this article was to (1) identify the various
clinical and imaging modalities described for assessing leg
length discrepancy; (2) report the available data on the
Each author certifies that he or she has no commercial associations
(eg, consultancies, stock ownership, equity interest, patent/licensing
arrangements, etc) that might pose a conflict of interest in connection
with the submitted article.
S. Sabharwal (&), A. Kumar
Division of Pediatric Orthopaedics, Department of Orthopaedics,
UMDNJ—New Jersey Medical School, Newark, NJ, USA
e-mail: sabharsa@umdnj.edu
123
Clin Orthop Relat Res (2008) 466:2910–2922
DOI 10.1007/s11999-008-0524-9

accuracy and interobserver and intraobserver reliability for
each assessment tool; (3) compare the reported results for
various assessment tools for LLD; and (4) discuss the
potential advantages and pitfalls that have been described
with each assessment tool.
Search Criteria and Strategies
We performed a Medline search of articles published from
1950 to July (week 2) 2008. Three separate search strategies
were employed using distinct search terms. The first search,
using the terms: ((limb length or leg length) and discrepancy
and measurement).mp. [mp =title, original title, abstract,
name of substance word, subject heading word] yielded 59
articles. The second search, using the terms: ((limb length or
leg length) and discrepancy and diagnosis).mp. [mp =title,
original title, abstract, name of substance word, subject
heading word] yielded 60 articles. The third search, using
the terms: ((limb length or leg length) and discrepancy and
scanogram).mp. [mp =title, original title, abstract, name of
substance word, subject heading word] yielded 16 articles.
There were 20 articles that appeared in more than one of the
three searches, yielding a total of 115 unique articles
(Fig. 1). We also reviewed relevant book chapters along
with the accompanying bibliography from two pediatric
orthopaedic textbooks (Morrissy and Weinstein [29],
Shapiro [40]). Only those articles that described a method
used to assess leg-length discrepancy and/or evaluated the
accuracy, and interobserver and intraobserver variability of
the assessment tool were included in this review. Articles
focusing on the etiology, prediction, and treatment of LLD
as well as those with no English abstract were excluded. Any
articles that described intraoperative assessment of the
length of a single lower extremity without assessing LLD
were also excluded. The current review is based on infor-
mation available from 42 distinct articles (Fig. 1).
A brief description of each available method used to
determine LLD, results of our literature review, including
data comparing two or more measurement techniques, are
detailed in the relevant sections. The potential advantages
and pitfalls of each modality are presented in the Discus-
sion section.
Methods used for Assessing Leg-length Difference
Clinical Techniques
Tape measure
A tape measure is typically used to measure the length of
each lower extremity by measuring the distance between
the anterior superior iliac spine (ASIS) and the medial
malleolus and is referred to as the ‘‘direct’’ clinical method
for measuring LLD (Fig. 2). However, differences in the
girth of the two limbs, and difficulty in identifying bony
prominences as well as angular deformities can contribute
to errors using this clinical measurement tool. Moreover,
there are certain causes of LLD such as fibular hemimelia
and posttraumatic bone loss involving the foot where a
significant portion of the limb shortening is distal to the
ankle mortise. Thus, it may be more accurate to measure
the true length from the pelvis to the bottom of the heel as
it is more easily reproducible and can account for short-
ening distal to the ankle. In some cases, lengths of the
appendicular skeleton may be equal, but apparent short-
ening may result from pelvic obliquity or contractures
around the hip and knee joints. An apparent leg length can
be measured from the umbilicus to the medial malleoli of
the ankle (Fig. 2).
Rondon et al. [35] compared true and apparent mea-
surements of LLD using clinical methods with radiographic
measurement of LLD in 17 adult patients. Despite high
interobserver reliability of the true (ICC, 0.99) and apparent
(ICC, 0.88) methods of clinically assessing LLD, the
MEDLINE search
(1950 – July week 2, 2008)
59 articles identified
from search: ((limb
length OR leg length)
AND discrepancy AND
measurement)
60 articles identified
from search: ((limb
length OR leg length)
AND discrepancy AND
diagnosis)
16 articles identified
from search: ((limb
length OR leg length)
AND discrepancy AND
scanogram).
115 abstracts reviewed
20 duplicate articles
excluded
Total of 42 articles reviewed
94 articles excluded based
on exclusion criteria.
(See text for details)
135 article titles reviewed
21 additional articles
identified from
bibliography of
2 text books 29, 40
21 articles reviewed
Flow diagram of search criteria and strategy
Fig. 1 A flow diagram outlines the search criteria and methodology
employed that lead to the 42 pertinent articles on methods for
assessing leg length discrepancy.
Volume 466, Number 12, December 2008 Assessing Leg Length Discrepancy 2911
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concordance between the true measurement and radio-
graphic assessment (ICC, 0.80) and apparent method and
radiographic assessment (ICC, 0.75) was lower. In a pro-
spective study of 10 adults with LLD and nine
asymptomatic volunteers, Beattie et al. [7] compared the
variability of measurements using tape measure with a
scanogram. A single examiner examined the LLD of all 19
subjects using a tape measure from the ASIS to medial
malleolus on two separate occasions and compared the
clinical results with those obtained using a scanogram. The
mean value obtained from the two clinical measurements
correlated better with the radiographic measurement of
LLD (ICC, 0.793) than those obtained during the first (ICC,
0.683) or second (ICC, 0.790) clinical assessment. The tape
measurements were less reliable in the healthy subjects
compared to those individuals with LLD. The authors
cautioned against relying solely on clinical assessment of
LLD and encouraged using the average value of two sep-
arate measurements when using a tape measure to assess
LLD. In another study, Cleveland et al. [8] compared tape
measurements of LLD of 10 erect patients with standing
and supine radiographs. They reported a statistically sig-
nificant difference (p \0.05) and poor to moderate
correlation when comparing the clinical and radiographic
techniques.
Standing on Blocks
Another method to measure LLD is to level the pelvis of
the erect patient by placing blocks of known height under
the short limb. This is referred to as the ‘‘indirect’’ clinical
method for measuring LLD (Fig. 3). This method takes
into account the disparity in foot height between the two
limbs and also aids in determining the functional LLD
(which may be different from the actual LLD) by using
varying heights of the block to establish the additional
length required for the patient to feel level.
Hanada et al. [15] assessed the reliability and validity of
measuring LLD using ‘‘iliac crest palpation and book
correction’’ in adult subjects with simulated LLD ranging
from 7 to 53 mm and compared clinical observations with
Fig. 3 Placing blocks of known height beneath the heel of the short
leg to level the pelvis allows ‘‘indirect’’ measurement of leg length
discrepancy. This method is slightly more reliable and accurate than
use of the tape measure. Reprinted with permission from Morrissy
RT, Weinstein SL, eds. Lovell and Winter’s Pediatric Orthopedics.
Philadelphia: Lippincott Williams & Wilkins; 2006 [29].
Fig. 2 A ‘‘direct’’ measurement using a tape measure can be utilized
to measure the ‘‘true’’ leg length from the anterior superior iliac spine
(ASIS) to the medial malleolus. The ‘‘apparent’’ leg length is
measured from the umbilicus to the medial malleolus. Reprinted with
permission from Morrissy RT, Weinstein SL, eds. Lovell and Winter’s
Pediatric Orthopedics. Philadelphia: Lippincott Williams & Wilkins;
2006 [29].
2912 Sabharwal and Kumar Clinical Orthopaedics and Related Research
123

those obtained using a standing AP view of the pelvis. The
intraobserver (ICC, 0.98) and interobserver (ICC, 0.91)
reliability for the clinical measurement was high with a
mean difference of 1.6 mm in the measurement of LLD for
the same observer and 1 mm between two observers. The
iliac crest palpation method tended to underestimate the
induced LLD by an average of 3.8 mm and underestimated
the LLD measured on a standing radiograph of the pelvis
by an average of 5.1 mm. Jonson and Gross [20] reported
reliability data for measuring LLD using the block method
in healthy adult Naval officers. Based on the measurements
by two experienced physical therapists, the intraobserver
(ICC, 0.87) and interobserver (ICC 0.70) reliability was
high. The mean absolute difference in measurement was
1.7 mm for intraobserver and 2.2 mm between the two
observers. Aspegren et al. [4] compared the visual cor-
rection using the block method to assess LLD with two
erect AP pelvis radiographs, one with and the other without
the same height of the lift that was used to visually level
the pelvis on 41 consecutive patients who presented to a
chiropractic clinic for back pain. The authors reported a
correlation between the two methods (Eta =0.885).
Lampe et al. [24] compared the agreement in measuring
LLD between two clinical methods, that is, use of a tape
measure and standing blocks with orthoroentgenograms in
190 children attending a limb lengthening clinic. Ninety-
five percent of the measurements using the wooden boards
were within -14 and +16 mm of the results obtained using
radiography. The tape measure had significantly less
agreement. Terry et al. [43] assessed interobserver and
intraobserver variability of three clinical methods of
assessing LLD in 16 patients among four observers with
different levels of training. The clinical methods included
direct measurement with a tape measure from the ASIS to
the lateral malleolus, ASIS to medial malleolus, and
standing on blocks. All three clinical measurement tech-
niques had high reliability with intraobserver intraclass
correlation coefficients (ICC) of 0.88, 0.78, and 0.86
respectively and interobserver ICC of 0.83, 0.8, and 0.83,
respectively. However, the direct measurement using a tape
measure on a full-length slit scanogram measurement was
more reliable with intraobserver ICC of 0.99 and intraob-
server ICC of 0.98. Harris and coworkers [16] compared
assessment of LLD using clinical methods including a tape
measure from the ASIS to medial malleolus and the block
test with CT scanogram findings in 35 adults following a
femoral shaft fracture. There was a strong correlation
between the two clinical methods (p =0.003). The tape
measurement and block test correlated well with the
patient-perceived LLD, while the CT scanogram did not
correlate well. Moreover, there was no correlation between
the CT scanogram and the two clinical methods with a
mean absolute difference of 7.2 mm in assessing LLD
between the clinical methods and CT scan. The authors
suggested that the physical exam may be more clinically
relevant than the CT scanogram.
Authors in the field of chiropractic medicine, physical
therapy, and podiatry have described other methods such as
the prone leg exam, visual postural analysis [6,11,33,34],
and various hand-held devices to check pelvic tilt [30,31]
that have not been adequately studied and we believed
were beyond the scope of this publication.
Imaging Methods
Plain Radiography
The three distinct techniques for assessing LLD using
standard radiography include orthoroentogenogram, scan-
ogram, and teleoroentgenogram (Fig. 4). A description of
all three radiographic methods is followed by a review of
the reliability and accuracy of these techniques collec-
tively. Some of the studies comparing clinical evaluation
with radiographic techniques have already been described
in the previous section.
Orthoroentogenogram
The orthoroentogenogram was initially described by Green
in 1946 [13]. This radiographic technique was developed to
minimize measurement error secondary to magnification
by using three distinct exposures centered over the hip,
knee, and ankle [13]. This imaging method differs from a
scanogram in that a longer cassette is required for the
orthoroentogenogram, with an additional burden of cost,
storage, and special equipment (Fig. 4A).
Scanogram
There is some inconsistency in the literature regarding the
term ‘‘scanogram.’’ The term ‘‘scanogram’’ may have
been derived from the technique of slit scanography,
described in 1937 [28], in which the xray beam is tightly
collimated to a thin transverse slit that exposes the film as
the xray tube is moved from one end of the limb to
another. Others have used the term ‘‘scanogram’’ [29,38,
40] to describe a modification of the orthoroentgenogram
taken with three separate exposures centered at the hip,
knee, and ankle using a standard-sized cassette
(35 943 cm) as opposed to the long cassette
(35 9110 cm) as was originally described for an ortho-
roentgenogram [13]. A technique quite similar to the
currently used scanogram was described by Merrill in
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1942, although the term ‘‘scanogram’’ was not used [27].
He described a specially constructed 18 948 inch ply-
wood grid with copper wires that were incorporated 1
inch apart along with lead numbers placed on the even-
numbered wires. The patient lay supine on the wooded
grid with sandbags at the feet and straps across the thighs.
Three radiographic exposures were made, one each cen-
tered over the ankle, knee and hip joints while the patient
lay still. Currently, the scanogram is made with the lower
limbs similarly positioned with both patellae pointing
towards the ceiling and a radio-opaque ruler taped to the
table between the limbs. The patient-to-tube distance is
typically 101 cm. Three separate AP images are obtained
centered over the hip, knee, and ankle joints, using three
separate 35 943-cm cassettes (Fig. 4B). The film cas-
sette is moved under the patient between exposures while
the patient remains motionless between the three
exposures.
Teleoroentgenogram
The teleoroentgenogram is a full-length standing AP
radiograph of the lower extremity. It consists of a single
radiographic exposure of both lower limbs, with the xray
beam centered at the knee from a distance of approxi-
mately 6 feet (180 cm) while the patient stands erect with
both patellae pointing directly anteriorly (Fig. 4C). An
attempt is made to level the pelvis with an appropriately
sized lift placed under the short limb. If both iliac crests are
at the same level, indicating equalization of LLD, one can
simply measure the height of the lift under the short limb to
calculate the LLD.
Several authors [13,18,29,38] have mentioned mag-
nification error related to assessment of limb lengths when
using a teleoroentgenogram. The magnitude of the mag-
nification error is dependent on various factors including
the length and girth of the limb, distance of the xray source
Fig. 4A–C (A) An orthoroentgenogram utilizes three radiographic
exposures centered over the hip, knee and ankle joints in order to
minimize magnification error. A single large cassette is placed under
the patient who remains laying still between the three exposures.
Reprinted with permission from Morrissy RT, Weinstein SL, eds.
Lovell and Winter’s Pediatric Orthopedics. Philadelphia: Lippincott
Williams & Wilkins; 2006 [29]. (B) The scanogram technique also
utilizes three radiographic exposures, one each centered over the hip,
knee and ankle joint in order to minimize magnification error. The
patient remains supine next to a calibrated ruler and unlike the
orthoroentgenogram, the standard length radiographic cassette is
moved for the three exposures. Reprinted with permission from
Morrissy RT, Weinstein SL, eds. Lovell and Winter’s Pediatric
Orthopedics. Philadelphia: Lippincott Williams & Wilkins; 2006
[29]. (C) A teleoroentgenogram consists of a single long cassette
placed behind the patient, while the xray beam is centered over the
knee joint. It is preferable to do this study with the patient standing.
While this technique is subject to magnification, less radiation
exposure and opportunity to comprehensively assess the entire
extremity for underlying etiology and deformity analysis makes this
imaging tool an attractive option for detailed assessment of leg length
discrepancy. Reprinted with permission from Morrissy RT, Weinstein
SL, eds. Lovell and Winter’s Pediatric Orthopedics. Philadelphia:
Lippincott Williams & Wilkins; 2006 [29].
2914 Sabharwal and Kumar Clinical Orthopaedics and Related Research
123

to the cassette, and divergence of the xray beam. Green
et al. [13] compared the magnification produced by a
teleoroentgenogram with a supine orthoroentgenogram.
Using 10 adult human skeletons they reported a mean
magnification of 4.5% (1.8 cm) for the femoral segment
and 3% (0.9 cm) for the tibial segment. Because these
specimens did not have LLD, the authors were unable to
comment on the difference in limb lengths measured by the
two imaging techniques. However, based on their clinical
experience, they did comment that although the teleo-
roentgenogram may not measure the true length of the
bone, it ‘‘fairly accurately’’ assesses the relative lengths of
the two extremities at a single exam [13].
Machen and Stevens [26] cited seven cases of children
with LLD in which, compared to the scanogram, the
standing full-length radiograph (teleoroentgenogram)
revealed more information regarding underlying diagnosis
and lower-limb alignment. They suggested that the scan-
ogram may be superfluous and that the teleoroentgenogram
was more clinically relevant in evaluating patients with
LLD. Cleveland et al. [8] compared the LLD measure-
ments using digital standing (teleoroentgenogram) and
supine (orthoroentgenogram) radiographs in 10 adults with
back pain. Using 10 mm as the threshold for meaningful
difference, they reported no difference between the two
tests. Linear regression analysis of the calculated LLD
using the standing and supine radiographs demonstrated
moderate correlation (r
2
=56.75). Despite a magnification
of approximately 5%, the measurement of LLD using full-
length standing AP radiographs is very similar in accuracy
to the scanogram, especially on the absence of significant
mechanical axis deviation [38]. In another study, Sabharwal
et al. [36] compared the measurements based on full-length
standing radiographs (teleoroentgenograms) before and
after removal of a circular external fixator. They found the
mean absolute difference in the radiographic measurement
of limb lengths between the two radiographs to be 20 mm
(p \0.0001) for the ipsilateral and 20.2 mm (p \0.0001)
for the contralateral unaffected extremity. The authors
cautioned clinicians against relying on the teleoroentgeno-
gram for assessing lower-limb length and alignment in
patients with an overlying circular external fixator. Other
techniques such as a lateral scanogram or a biplanar CT
scan [1,12,19] may improve the accuracy of LLD mea-
surement in such patients.
Computed Radiography
Computed radiography (CR) is a relatively recent advance
in the measurement of leg-length discrepancy that is
gaining popularity [37,38] (Fig. 5). In order to obtain a
full-length standing radiograph of the lower extremities,
the minimum patient-to-tube distance is 203 cm, and is
increased for taller individuals. A latent image is pro-
duced that is stored on a photostimulatable phosphor
receptor contained in a standard radiographic cassette.
The images are recorded on a computed radiography
long-length imaging system utilizing a vertical cassette
holder with three individual 35 943-cm CR storage
phosphor cassettes. The three images are then stitched at
the CR reader console, using customized software. The
composite image thus obtained is transferred digitally and
can be manipulated by an automated system such as a
picture archiving and communication system (PACS)
resulting in a film radiograph. The operator can enhance
the final image by using the computer to adjust the image
parameters. As a result, quality radiographs can be
obtained consistently with a significant reduction in the
radiation dose compared to standard film screen systems,
a feature that is very useful for patients who require
repeated radiographic examination due to leg-length dis-
crepancy [21,38].
Sabharwal et al. [38] evaluated 111 patients with LLD
who had undergone CR-based scanogram and teleoroent-
genogram on the same day. Despite a 4.6% (33 mm)
magnification noted when measuring the absolute length of
the lower extremity with the standing radiograph, the mean
difference in LLD measurement between the two CR
techniques was only 5 mm. There was a strong correlation
(r =0.96) in the measurement of LLD between the two
methods. Patients with less than 20 mm of mechanical axis
deviation on the standing radiograph had better correlation
with the scanogram than those with larger magnitude of
malalignment. The mean radiation dose was 1.6 to 3.8
times greater for the CR-based scanogram study than the
teleoroentgenogram and the charges of both studies were
identical. Thus, the authors supported using a CR-based
standing full-length radiograph as the initial imaging study
when assessing a patient with LLD. In another study,
Sabharwal et al. [37] reported on the intraobserver and
interobserver reliability among five blinded observers with
varying degrees of experience to assess LLD using CR-
based supine scanograms and standing teleoroentgeno-
grams of 70 patients. The intraobserver reliability for all
five observers was high for scanogram (ICC, 0.975–0.995)
as well as teleoroentgenogram (ICC, 0.939–0.996). The
mean absolute difference for intraobserver reliability was
1.5 to 2.6 mm for scanogram and 1.5 to 4.6 mm for the
standing radiograph. The interobserver reliability among
the five observers was also high for scanogram (ICC,
0.979) and teleoroentgenogram (ICC, 0.968). The mean
absolute difference for interobserver reliability was
2.6 mm for scanogram and 3 mm for the standing
radiograph. The authors recommended using the teleo-
roentgenogram for evaluating patients with LLD since the
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reliability was as good as the scanogram and allowed for a
more comprehensive examination of the lower extremity.
Microdose Digital Radiography
Microdose digital radiography is another form of com-
puter-aided imaging that substantially reduces the radiation
exposure to patients in comparison with conventional
radiographic techniques [3]. Using a vertical gantry, the
patient stands in front of the xray assembly and remains
stationary during the 20-second scanning process [3].
A continuous series of photon beams collimated to act as a
point source are projected through the patient to strike a
computerized detector. The source assembly and detector
move together, scanning the field in a line-by-line motion
so that the beam is always horizontal to the patient. As the
detector is extremely efficient in detecting and processing
the point source of xray photons, a patient receives an
exposure of only 1 to 2 mrad during the scan. This nearly
negligible radiation exposure to the patient makes the
technique especially attractive for problems that require
serial radiograph evaluation such as progressive leg-length
inequalities.
In a study of 25 children with LLD, Altongy et al. [3]
found microdose digital radiography more accurate than
orthoroentgenograms. Compared to the digital radiography,
orthoroentgenographic measurements of leg lengths and
LLD were larger by an average of 3 mm and 4 mm. The
largest reported interobserver difference in measurement of
leg length and LLD was 4 mm and 6 mm respectively for
orthoroentgenograms and 6 mm and 8 mm for microdose
digital radiographs.
Ultrasound
Ultrasound has been used to measure leg length discrep-
ancy by various authors from Europe [22,23,42]. In this
technique, the ultrasound transducer is used to identify the
bony landmarks at the hip, knee, and ankle joints [42].
Terjesen et al. [42] compared the measurements of LLD
using real-time ultrasonography in 45 patients with the
results obtained using standing radiographs. There was a
Fig. 5A–B (A) Standing AP radiograph of the lower extremity
(modified teleoroentgenogram) performed using computed radiogra-
phy on a young child with a congenital shortening of the tibia of
approximately 4.5 cm. This radiograph is made with the child standing
on a appropriate height lift under the short leg to level the pelvis.
Besides assessing leg length discrepancy, along with length of the
whole leg (W) as well as femur (F) and tibia (T), this imaging modality
can be used to measure mechanical axis deviation (MAD) and joint
orientation angles around the knee. (B) The modified scanogram of the
same child as shown in Aperformed using computed radiography.
Unlike a teleoroentgenogram, this imaging modality requires three
radiographic exposures; one each centered over the hip, knee and ankle
joints. Although a scanogram has less magnification error compared to
a teleoroentgenogram, the scanogram is performed supine, is typically
associated with greater radiation exposure, does not allow visualization
of the entire length of the femur (F) and tibia (T) and fails to account for
any shortening related to the foot. Reprinted with permission from the
Journal of Bone and Joint Surgery, Inc., from Sabharwal S, Zhao C,
McKeon JJ, McClemens E, Edgar M, Behrens F. Computed radio-
graphic measurement of limb-length discrepancy. Full-length standing
anteroposterior radiograph compared with scanogram. J Bone Joint
Surg Am. 2006;88:2243–2251 [38].
2916 Sabharwal and Kumar Clinical Orthopaedics and Related Research
123

linear relationship between the findings of the two tech-
niques (r =0.94) with a mean difference of -1.9 mm, and
the limits of agreement were -9.1 to 5.3 mm. The mean
difference in the measurement of LLD between two
examiners using ultrasound was 1.7 mm. Although the
ultrasound was slightly less reliable than the standing
radiograph, given the lack of radiation, the authors rec-
ommended the ultrasound as the initial screening tool in
patients being evaluated for LLD. Defrin et al. [9] reported
high intraobserver reliability (ICC, 0.99) of measuring
LLD using ultrasound in 33 patients with low back pain.
Krettek et al. [23] compared the LLD measurements
obtained with ultrasonography with two clinical methods
(tape measure and standing blocks) and with teleoroent-
genogram in 50 patients. The mean divergence in
measurement of LLD between the ultrasound and standing
radiograph was 0.9 mm, with a maximum of 6.4 mm. The
clinical methods with mean divergence of -1.2 mm (tape
measure) and -1 mm (standing block) were slightly less
accurate than ultrasound measurement.
CT Scanogram
Digitalized images obtained with a CT scan have also been
used for measuring LLD [1,2,12,17,19,44]. Typically,
an anteroposterior (AP) scout view of the bilateral femurs
(Fig. 6) and tibias are obtained, although use of lateral
view CT scanograms has also been reported [1,12].
Cursors are placed over the superior aspect of the imaged
femoral head and the distal portion of the medial femoral
condyle [2,17,19] with the distance between these two
cursors representing the length of the individual femur. The
tibial length is similarly determined by measuring the
distance between cursors placed at the medial tibial plateau
and the tibial plafond. When obtaining these measure-
ments, the patient lays supine on the CT scanner tabletop,
which moves through a collimated xray beam from a sta-
tionary source.
Huurman et al. [19] studied in-vitro precision and
accuracy of CT scanogram and orthoroentgenogram using
adult femoral and tibial specimens that were placed flat on
a table top. The accuracy and interobserver variability for
both techniques was very similar, with less than 3 mm
difference in measurement, compared to the actual length
of the specimens that was measured using calipers. How-
ever, when the specimens were angled in the vertical plane,
the lateral CT scanogram was significantly more accurate
(p =0.005), while the orthoroentgenogram underestimated
length related to apparent foreshortening of the bone.
Aaron et al. [1] compared orthoroentgenography and lateral
CT scanogram for assessing LLD using 10 adult lower
limb cadaveric specimens at four predetermined degrees of
knee flexion of 0, 15°,30°, and 45°. They reported no
significant difference between the actual length of the
measured specimen and that assessed by the lateral CT
scanogram for all measurements, while the orthoroent-
genogram was less accurate in measuring length of the tibia
and the entire limb in specimens with knee flexion of 30°or
greater. Moreover, the radiation dose with the CT scano-
gram was 80% less than that delivered during the
orthoroentgenogram. The length of time required to com-
plete the imaging and cost was comparable for the two
radiographic evaluation methods. Temme et al. [41] com-
pared the measurements of CT scanogram and
orthoroentgenogram using dried femur specimens and also
found the CT scanogram more accurate. Aitken et al. [2]
compared AP CT scanogram using a scout view and con-
ventional scanogram using plain radiography in 24 patients
(18 children, six adults). All studies were evaluated by two
radiologists independently and revealed high correlation
(r =0.99) for both techniques. While no statistical differ-
ences in measurements were found between the two
imaging techniques, there was a trend for underestimation
of length by 2 mm using the CT scan in patients with bony
segments that were greater than 30 cm long. The cost of
the two studies was similar although the radiation dose was
three to six times less with the CT scan compared to a
scanogram. Porat and Fields [32] compared the accuracy of
Fig. 6 An AP CT scanogram of an adult patient following surgical
treatment of fractures of the pelvis and right femoral shaft demon-
strates a mild (2 mm) LLD in the femoral segment (courtesy of Dr
Mark C. Reilly).
Volume 466, Number 12, December 2008 Assessing Leg Length Discrepancy 2917
123

conventional orthoroentgenography with CT scanogram for
measuring LLD in 17 patients and reported similar accu-
racy of both techniques with a 66% reduction in radiation
dose with a CT scanogram. Badii et al. [5] reviewed pelvic
asymmetry based on the AP scout view of abdominal CT
scans in 323 patients. Pelvic asymmetry ranged from -11
to 7 mm. Pelvic asymmetry greater than 5 mm was found
in 17 (5.3%) and greater than 10 mm in two (0.6%) of the
patients. Based on assessment of 30 CT scans by three
examiners, the interobserver reliability of measuring pelvic
asymmetry on abdominal CT scans was high (ICC, 0.91).
MRI Scan
Although traditionally used for soft tissue imaging, MRI
has become an increasingly popular method to evaluate
bony abnormalities as well. MRI images were obtained
using a T1 weighted spin echo sequence and the best
coronal images were selected for standardized assessment
of femoral length using the classic bony landmarks of the
femoral head and medial femoral condyle [25].
In a recent study, Leitzes et al. [25] compared MRI
scanogram with CT and radiographic scanogram using 12
cadaveric femoral specimens to assess the potential for
assessing LLD. Three orthopaedists with different levels of
training performed two separate measurements using each
technique. Accuracy was also assessed by comparing the
measurements obtained with the imaging techniques and
true measurement of the femoral length using an electronic
caliper. The intraobserver and interobserver reliability was
very high (ICC, 0.99) for all three techniques and all
examiners. However, compared to the true length of the
femur, the mean absolute difference was 0.52 mm for the
radiographic scanogram, 0.68 mm for the CT scanogram,
and 2.90 mm for the MRI scanogram.
Discussion
While there are several different methods available to the
clinician for the assessment of LLD, we were unable to find
an in-depth review of the various clinical and imaging
modalities as the subject of a single manuscript. Our goal
was to enumerate the various modalities that have been
described for assessing leg length discrepancy, including
the accuracy and interobserver and intraobserver reliability
for each technique, to compare the reported results for
various assessment tools for LLD, and discuss the potential
advantages and pitfalls that have been described with each
method. We identified certain trends that were noted across
several studies discussed below, along with the potential
advantages and pitfalls of each method.
While using a tape measure is an easy, safe, and non-
invasive means of assessing LLD, it is less reliable when
compared to radiographic techniques such as a scanogram
[7,8,10,43]. The average of two tape measurements of the
distance between the ASIS and medial malleolus appears to
have acceptable validity and reliability when used as a
screening tool for assessing LLD [14]. However, there are
potential sources of error with tape measurements related
to differences in leg circumference, angular deformities,
and difficulty in accurately palpating bony prominences as
well as joint contractures. While the use of standing blocks
under the short leg to level the pelvis is slightly more
reliable than tape measurement, such a method may still
not be precise enough for serial monitoring of LLD [43].
There is general consensus that radiographs are more
accurate and reliable than clinical exam for analysis of
LLD [8,24,43]. Several authors have reported the results
of LLD measurement using a variety of imaging techniques
such as orthoroentgenogram [13], CR-based teleoroent-
genogram [38], slit scanogram [28], microdose digital
radiography [3], CT scanogram [1,2,19], ultrasound [42],
and MRI scanogram [25]. One needs to consider several
issues such as reliability, accuracy, magnification, radiation
dose, cost, need for special equipment, convenience, and
opportunity to image the entire extremity when choosing
the imaging technique for evaluating patients presenting
with LLD (Table 1).
A scanogram is one of the most commonly used meth-
ods for assessing LLD. It has excellent reliability [37] and
minimal, if any, magnification error [38]. However, as
supine radiographs that require the patient to remain still
between the three radiographic exposures, an orthoroen-
togenogram and a scanogram are prone to errors related to
the patient moving between the exposures. The radiation
exposure with scanogram and orthoroentgenogram is also
substantially greater than that associated with a full-length
standing radiograph and a CT scanogram [1,26,38]. This
may be related to the need for three separate radiographic
exposures with the scanogram and orthoroentgenogram
compared to the single exposure centered at the knee with
the standing radiograph as well as the closer xray tube-to-
patient distance utilized while performing a scanogram.
While taking a scanogram, the xray tube must be centered
precisely over the joint since even a minor deviation of the
beam can result in measurement error of several millime-
ters due to distortion by magnification [26]. Errors in
measurement are often seen in patients with clinically
important limb-length inequalities when the individual
joints of the two limbs are at substantially different levels
and thus not visualized on the same radiograph [26].
Moreover, a scanogram cannot detect angular deformities
of the lower limb and may underestimate the LLD in
patients with discrepancies in foot height [26,38]. Patients
2918 Sabharwal and Kumar Clinical Orthopaedics and Related Research
123

Table 1. Comparison of methods for assessing leg length discrepancy
Methods Reliability
*
Accuracy
*
Magnification Approximate
radiation
exposure
(mrads) [26]
Approximate
charges (U.S.
dollars)
Radiographic
deformity
analysis
Incorporation
of height of
the foot
and pelvis
Typical
availability
in U.S.
Weight
bearing
Clinical
Supine tape
measure—
‘‘Real’’
(ASIS to
malleolus)
++None None Office visit Not applicable No Yes No
Supine tape
measure—
‘‘Apparent’’
(umblicus
to malleolus)
++None None Office visit Not applicable Partial Yes No
Standing blocks ++ + None None Office visit Not applicable Yes Yes Yes
Imaging
Teleoreont-
genogram
++++ +++ *5% 42 $95 [26] Yes Yes Varies Yes
Orthoroent-
genogram
+++ +++ Minimal 200 $110 [26] Minimal No Varies No
Scanogram ++++ +++ Minimal 200 $110 [26] No No Varies No
CR ++++ +++ Varies with
technique
(scanogram
versus
teleoroengen-
ogram)
Varies with
technique, less
exposure
than standard
radiography
$137 [38] Varies with
technique
(scanogram
versus tele-
oroengenogram)
Varies with
technique
Varies Varies with
technique
(scanogram
versus
teleoroen-
genogram)
MDR +++ ++++ None 2 $75 [26] Yes Yes No Yes
Ultrasound +++ ++ None None Not reported No No No Yes
CT scan (digital
localization
image)
++++ ++++ Minimal 60 $60 [26] Minimal None Varies No
MRI ++++ +++ Minimal None Not reported Not reported Not reported No No
CR =computed radiography; MDR =microdose digital radiography.
* Please see text for detailed analysis. For simplicity, the increasing number of ‘‘+’’ signs indicate greater degree of reliability/accuracy.
Volume 466, Number 12, December 2008 Assessing Leg Length Discrepancy 2919
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presenting with unequal leg lengths often have associated
angular deformities of the lower limb. Since the entire
lower extremity is imaged on a single radiograph with the
patient in the erect position, a comprehensive analysis of
limb deformities can be performed as well, along with the
assessment of LLD [26,38,39]. Furthermore, unlike a
scanogram, the difference in height of the feet is incorpo-
rated in the measurement of LLD when using the full-
length standing radiograph. There are certain prerequisites
that should be met in order to avoid potential errors in
using this measurement for clinical decision making. For
the standing full-length radiograph, the patient should be
stood erect with the pelvis clinically level and the feet
plantigrade by using an appropriate-sized lift under the
short limb. This will avoid underestimation of the LLD that
can occur with the patient plantarflexing the ankle on the
short side and flexing the contralateral knee in an attempt
to level the pelvis. Similarly, any lower extremity joint
contractures or overlying external fixators can diminish the
accuracy of LLD measurement using either of the two
imaging techniques [36]. However, there are potential
pitfalls with using this radiograph, including the need for
special radiographic equipment such as grids, filters, and
processors along with the need for long radiographic cas-
settes that may not be readily available with recent
advances in digital imaging and can be difficult to store.
Computed radiography (CR) does not require these
additional tools while at the same time uses standard
radiographic equipment. The full-length images obtained
using CR are readily available on personal computers for
preoperative planning and patient/ family education
[26,38]. Despite a 5% magnification ‘‘error’’ in the mea-
surement of the entire length of the lower extremity, there
is minimal effect on assessment of LLD. Furthermore, by
placing magnification markers and a ruler next to the
patient, this magnification error can be further reduced
(Fig. 7). Proper training and supervision of the radiology
technicians regarding the correct technique and patient
positioning for performing standing radiographs, especially
with rapidly changing technology, is also critical to ensure
appropriate and reproducible imaging studies.
The cost of microdose digital radiography (MDR) is
comparable to other imaging techniques [3,26], although
special equipment is necessary. Moreover, unlike a CT
scan, the digital scan has a field length of 150 cm that is
sufficient for imaging the entire lower extremity in a single
exposure for most patients [3]. However, this technique is
not readily available and not as convenient as a full-length
standing AP radiograph that is obtained using computed
radiography.
The benefits of ultrasound are that it is inexpensive, does
not involve any radiation exposure, is reliable in the hands
of experienced users, and is thus a convenient and useful
method of assessing LLD [22,23]. However, unlike a full-
length standing radiograph, an ultrasound does not allow
for a comprehensive analysis of the lower extremity
including angular deformities and may be less accurate
than radiographic methods. This technique may be a useful
screening tool in the hands of experienced users [42].
A CT scanogram has the advantages of displaying the
entire lengths of the femurs and tibias while minimizing the
measurement error. There is no magnification when the
structure to be measured is centered in the computerized
axial tomographic gantry [19]. While possibly needing
longer setup time, a CT scanogram has similar costs and
may be more accurate, with excellent reliability and less
gonadal radiation, than some of the plain radiographic
techniques [1,2,17,19,26,41]. In order to avoid under-
estimation of limb length, it may also be useful to perform
Fig. 7 A standing full-length computed radiograph (modified teleo-
roentgenogram) of a 14 year old patient following right sided tibial
lengthening for a 6 cm LLD. Note the use of a midline ruler and
magnification markers adjacent to the right hip, knee and ankle joints
to decrease the magnification error in measuring the residual LLD in
this child. Use of a small lift under the right leg to level the pelvis
may also have been useful.
2920 Sabharwal and Kumar Clinical Orthopaedics and Related Research
123

a lateral CT scanogram in patients with flexion contractures
of the hip or knee [1,19]. However, periarticular and
diaphyseal angular deformities as well as joint subluxation
and mechanical axis deviations are not as well ascertained
on these supine images compared to a standing radiograph.
Moreover, this technique is not readily available and usu-
ally requires prior scheduling in the department of
radiology or an imaging center.
Although an MRI scanogram does not expose patients to
ionizing radiation, the measurements obtained using this
technique are slightly less accurate than those obtained
with a radiographic scanogram or a CT scanogram [25].
Furthermore, an MRI scanogram has not been well-studied
in the clinical setting as an assessment tool for LLD, is
probably more expensive, may require sedation in some
children, typically requires a longer time to schedule and to
complete the study, and may be contraindicated in patients
with certain implantable devices. Thus, at this time a
supine MRI scanogram remains an investigational tool that
requires clinical validation before it can be recommended
for general use. Recently, MRI scanners that allow the
patient to weight bear during imaging have been introduced
in the U.S. market. Such an emerging technique may be an
attractive option to comprehensively assess length and
alignment of the lower extremities while avoiding radiation
exposure to the patient.
Based on our review of the literature, we found several
limitations in the available articles dealing with different
assessment tools for LLD. The majority of the studies were
retrospective case series with multiple confounding vari-
ables that were not clearly stated by the investigators.
Factors such as magnitude of LLD, level of training and
experience of observers, lack of blinding of observers,
undocumented body habitus (such as BMI) of subjects,
presence of angular deformities and contractures, use of
cadaveric and synthetic bone specimens versus live sub-
jects as well as limited number of patients can affect the
validity of the authors’ conclusions. Certainly, there are
ethical concerns with subjecting patients to multiple diag-
nostic modalities, especially those involving radiation.
However, future investigators can strengthen their research
methodology by employing more robust study design and
methodology. Our suggestions would include the follow-
ing: use well-designed prospective, multicenter studies
involving a larger number of subjects, clearly state and
discuss the confounding variables, perform appropriate
statistical analysis, perform adequate tests for reliability
and accuracy amongst blinded observers with different
levels of training and study emerging technologies that do
not involve radiation hazards, such as standing MRI and
ultrasound. Hopefully, such efforts can further aid clini-
cians in performing safe, reliable and accurate assessment
of patients presenting with LLD.
An ideal method for assessing LLD should be readily
available, accurate, reliable, and affordable, allow visuali-
zation of the entire lower extremity, minimize radiation
exposure, and have no magnification error. Although at
present there is no single imaging method that can be
considered ideal, based on our review of the literature, the
standing full-length AP computed radiograph of both lower
extremities with the pelvis level, along with use of a
magnification marker, should be the primary imaging
modality for the initial evaluation of LLD in the majority
of the patients. A CR teleoroentgenogram is not only an
accurate and reliable imaging tool, but the measurements
can be obtained with limited radiation exposure in a cost-
effective manner [20,21]. However, other techniques such
as a lateral scout CT scan may be more useful in cases with
severe angular deformities, especially those associated with
flexion deformities around the knee. In the upcoming years
other imaging modalities such as a standing MRI of the
lower extremities may prove a viable alternative, without
exposing patients to radiation hazards. On the other hand,
despite rapidly advancing technology, it is important to
consider that the accuracy and ease of obtaining measure-
ments of the patient using any imaging modality is not a
substitute for a thorough clinical assessment of the patient
presenting with LLD [18]. Moreover, clinical evaluation of
the patient with long-standing limb shortening, especially
with associated muscle weakness, using blocks under the
short limb can be used to estimate the amount of correction
that feels optimal, as this may be different from the true
LLD assessed with an imaging modality. Thus, a judicious
use of a comprehensive imaging method combined with an
astute clinical assessment is the most optimal means of
evaluating a patient presenting with leg-length discrepancy.
Acknowledgments We thank Dr. Caixia Zhao and Ms. Emily
McClemens, PA-C, for their assistance in preparing this manuscript.
References
1. Aaron A, Weinstein D, Thickman D, Eilert R. Comparison of
orthoroentgenography and computed tomography in the mea-
surement of limb-length discrepancy. J Bone Joint Surg Am.
1992;74:897–902.
2. Aitken GF, Flodmark O, Newman DE, Kilcoyne RF, Shuman
WP. Mack LA. Leg length determination by CT digital radiog-
raphy. AJR Am J Roentgenol. 1985;144:613–615.
3. Altongy JF, Harcke HT, Bowen JR. Measurement of leg length
inequalities by Micro-Dose digital radiographs. J Pediatr Orthop.
1987;7:311–316.
4. Aspegren DD, Cox JM, Trier KK. Short leg correction: a clinical
trial of radiographic vs. non-radiographic procedures. J Manip-
ulative Physiol Ther. 1987;10:232–238.
5. Badii M, Shin S, Torreggiani WC, Jankovic B, Gustafson P,
Munk PL, Esdaile JM. Pelvic bone asymmetry in 323 study
participants receiving abdominal CT scans. Spine. 2003;28:1335–
1339.
Volume 466, Number 12, December 2008 Assessing Leg Length Discrepancy 2921
123

6. Baylis WJ, Rzonca EC. Functional and structural limb length
discrepancies: evaluation and treatment. Clin Podiatr Med Surg.
1988;5:509–520.
7. Beattie P, Isaacson K, Riddle DL, Rothstein JM. Validity of
derived measurements of leg-length differences obtained by use
of a tape measure. Phys Ther. 1990;70:150–157.
8. Cleveland RH, Kushner DC, Ogden MC, Herman TE, Kermond
W, Correia JA. Determination of leg length discrepancy. A
comparison of weight-bearing and supine imaging. Invest Radiol.
1988;23:301–304.
9. Defrin R, Ben Benyamin S, Aldubi RD, Pick CG. Conservative
correction of leg-length discrepancies of 10 mm or less for the
relief of chronic low back pain. Arch Phys Med Rehabil.
2005;86:2075–2080.
10. Fisk JW, Baigent ML. Clinical and radiological assessment of leg
length. N Z Med J. 1975;81:477–480.
11. French SD, Green S, Forbes A. Reliability of chiropractic
methods commonly used to detect manipulable lesions in patients
with chronic low-back pain. J Manipulative Physiol Ther.
2000;23:231–238.
12. Glass RB, Poznanski AK. Leg-length determination with biplanar
CT scanograms. Radiology. 1985;156:833–834.
13. Green WT, Wyatt GM, Anderson M. Orthoroentgenography as a
method of measuring the bones of the lower extremities. J Bone
Joint Surg Am. 1946;28:60–65.
14. Gurney B. Leg length discrepancy. Gait Posture. 2002;15:195–
206.
15. Hanada E, Kirby RL, Mitchell M, Swuste JM. Measuring leg-
length discrepancy by the ‘‘iliac crest palpation and book cor-
rection’’ method: reliability and validity. Arch Phys Med Rehabil.
2001;82:938–942.
16. Harris I, Hatfield A, Walton J. Assessing leg length discrepancy
after femoral fracture: clinical examination or computed tomog-
raphy? ANZ J Surg. 2005;75:319–321.
17. Helms CA, McCarthy S. CT scanograms for measuring leg length
discrepancy. Radiology. 1984;151:802.
18. Horsfield D, Jones SN. Assessment of inequality in length of the
lower limb. Radiography. 1986;52:223–227.
19. Huurman WW, Jacobsen FS, Anderson JC, Chu WK. Limb-
length discrepancy measured with computerized axial tomo-
graphic equipment. J Bone Joint Surg Am. 1987;69:699–705.
20. Jonson SR, Gross MT. Intraexaminer reliability, interexaminer
reliability, and mean values for nine lower extremity skeletal
measures in healthy naval midshipmen. J Orthop Sports Phys
Ther. 1997;25:253–263.
21. Kogutt MS. Computed radiographic imaging: use in low-dose leg
length radiography. AJR Am J Roentgenol. 1987;148:1205–1206.
22. Konermann W, Gruber G. Ultrasound determination of leg length
[in German]. Orthopade. 2002;31:300–305.
23. Krettek C, Koch T, Henzler D, Blauth M, Hoffmann R. A new
procedure for determining leg length and leg length inequality
using ultrasound. II: Comparison of ultrasound, teleradiography
and 2 clinical procedures in 50 patients [in German]. Unfall-
chirurg. 1996;99:43–51.
24. Lampe HI, Swierstra BA, Diepstraten AF. Measurement of limb
length inequality. Comparison of clinical methods with orthora-
diography in 190 children. Acta Orthop Scand. 1996;67:242–244.
25. Leitzes AH, Potter HG, Amaral T, Marx RG, Lyman S, Widman
RF. Reliability and accuracy of MRI scanogram in the evaluation
of limb length discrepancy. J Pediatr Orthop. 2005;25:747–749.
26. Machen MS, Stevens PM. Should full-length standing antero-
posterior radiographs replace the scanogram for measurement of
limb length discrepancy? J Pediatr Orthop B. 2005;14:30–37.
27. Merrill OE. A method for the roentgen measurement of the long
bones. Am J Roentgenol Radium Ther Nucl Med. 1942;48:405–
406.
28. Millwee RH. Slit scanography. Radiology. 1937;28:483–486.
29. Moseley CF. Leg length discrepancy. In: Morrissy RT,
Weinstein SL, eds. Lovell and Winter’s Pediatric Orthopedics.
Philadelphia, PA: Lippincott Williams & Wilkins; 2006;1213–
1256.
30. Okun SJ, Morgan JW Jr, Burns MJ. Limb length discrepancy: a
new method of measurement and its clinical significance. JAm
Podiatry Assoc. 1982;72:595–599.
31. Petrone MR, Guinn J, Reddin A, Sutlive TG, Flynn TW, Garber
MP. The accuracy of the Palpation Meter (PALM) for measuring
pelvic crest height difference and leg length discrepancy. J Or-
thop Sports Phys Ther. 2003;33:319–325.
32. Porat S, Fields S. Limb length discrepancy determined by com-
puterized tomography and radiography [in Hebrew]. Harefuah.
1989;116:515–516.
33. Rhodes DW, Mansfield ER, Bishop PA, Smith JF. Comparison of
leg length inequality measurement methods as estimators of the
femur head height difference on standing Xray. J Manipulative
Physiol Ther. 1995;18:448–452.
34. Rhodes DW, Mansfield ER, Bishop PA, Smith JF. The validity of
the prone leg check as an estimate of standing leg length
inequality measured by Xray. J Manipulative Physiol Ther.
1995;18:343–346.
35. Rondon CA, Gonzalez N, Agreda L, Millan A. Observer agree-
ment in the measurement of leg length. Rev Invest Clin.
1992;44:85–89.
36. Sabharwal S, Badarudeen S, McClemens E, Choung E. The effect
of circular external fixation on limb alignment. J Pediatr Orthop.
2008;28:314–319.
37. Sabharwal S, Zhao C, McKeon J, Melaghari T, Blacksin M,
Wenekor C. Reliability analysis for radiographic measurement
of limb length discrepancy: Full-length standing anteroposterior
radiograph versus Scanogram. J Pediatr Orthop. 2007;27:
46–50.
38. Sabharwal S, Zhao C, McKeon JJ, McClemens E, Edgar M,
Behrens F. Computed radiographic measurement of limb-length
discrepancy. Full-length standing anteroposterior radiograph
comared with scanogram. J Bone Joint Surg Am. 2006;88:2243–
2251.
39. Saleh M, Milne A. Weight-bearing parallel-beam scanography
for the measurement of leg length and joint alignment. J Bone
Joint Surg Br. 1994;76:156–157.
40. Shapiro F. Pediatric Orthopedic Deformities. Basic Science,
Diagnosis, and Treatment. San Diego, CA: Academic Press;
2001;606–732.
41. Temme JB, Chu WK, Anderson JC. CT scanograms compared
with conventional orthoroentgenograms in long bone measure-
ment. Radiol Technol. 1987;59:65–68.
42. Terjesen T, Benum P, Rossvoll I, Svenningsen S, Floystad Isern
AE, Nordbo T. Leg-length discrepancy measured by ultraso-
nography. Acta Orthop Scand. 1991;62:121–124.
43. Terry MA, Winell JJ, Green DW, Schneider R, Peterson M, Marx
RG, Widmann RF. Measurement variance in limb length dis-
crepancy: Clinical and radiographic assessment of interobserver
and intraobserver variability. J Pediatr Orthop. 2005;25:197–
201.
44. Tokarowski A, Piechota L, Wojciechowski P, Gajos L, Kusz D.
Measurement of lower extremity length using computed tomog-
raphy [in Polish]. Chir Narzadow Ruchu Ortop Pol. 1995;60:
123–127.
2922 Sabharwal and Kumar Clinical Orthopaedics and Related Research
123