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THEJOURNALOFORTHOPAEDICANDSPORTSPHYSICALTHERAPY
Copyright O 1986 by The Orthopaedic and Sports Physical Therapy Sections of the
American Physical Therapy Association
Kinematic Effects of Heel Lift Use to
Correct Lower Limb Length
Differences*
WILLIAM D. BANDY, MA, PT, ATC,? WAYNE E. SINNING, PhD*
The effect of the heel lift to correct a limb length difference was studied by
electrogoniometry (elgons) in four male subjects with a limb length inequality
between 3/~6inch (0.48 cm) and 3h inch (0.95 cm). Six elgons were attached to
bilateral hip, knee, and ankle joints as the subject walked (3 mph) and jogged (6
mph) on the treadmill twice, once with the heel lift and once without. Recordings
from the elgons examined maximal flexion and extension during support and swing
phase, amplitude of movement (ROM), duration of each movement, and angular
velocity of each joint. Within the limitations of the study, the following conclusions
were drawn: 1) the addition of a heel lift did not appear to significantly affect
biomechanical measures of gait; and 2) insertion of a heel lift did tend to cause more
symmetrical movement for the maximum angle of hip extension and ROM of the
swing plantarflexion phase of the ankle but more asymmetrical ROM of the swing
flexion phase of the knee.
+
Research has shown that a lower limb length
Other writers have reached conclusions condifference (LLD) may be present in 25-93% (detrary to the authors previously reviewed. H ~ l tin, ~
pending on the source) of the p ~ p u l a t i o n . ~A~ ~ ~an
. ' investigation
~
of Swedish industrial and factory
LLD that may be considered minor (1b1/2 inch, 1workers, found no differences in the incidence of
2 cm) and not cause any problems in a nonathlete
LLD in workers complaining of lumbar spine trouor sedentary individual, may become a major
ble and the entire study population. Fisk and
problem in the active athlete. The constant, reBiagent4 state that "moderate degrees of leg
petitive strides made while training for a distance
length discrepancy played little if any part in the
event may be predisposing to several injuries.
etiology of back ache." G r ~ s sin, ~reviewing young
Symptoms that have been suggested to be
adults' perceptions on the functional effects of
caused by LLD include sciatica as well as pain in
LLD, found that individuals with less than an inch
the hip, knee, ankle, and iliotibial band.317.9.10.12.13
(2
cm) difference did not consider the discrepancy
The treatment for the alleviation of LLD is the
to
be a problem. However, neither investigator
insertion of a heel lift equal to the height of the
studied
athletes as a separate group.
discrepancy and inserted into the shoe of the
Only
one
investigation analyzed the changes
short leg in order to equalize the lengths of the
that
occur
with
the insertion of a heel lift2Inveslower
Several authors have suptigators hypothesized that the insertion of a heel
ported the theory suggesting that the use of the
heel lift ensures biomechanical symmetry of
lift had a positive effect on the running gait; howmovement which is essential to decrease the
ever, two problems arise. First, the study investichance of injury to an active i n d i ~ i d u a l . ~ . ~ . ' ~ . ~gated
~
the kinetic energy changes occurring in the
lower extremity but did not define the actual
changes in displacement occurring at the joints of
'A research project submitted to the Kent State University PERD
the body. Second, the study dealt with a LLD of
Graduate Department in partial fulfillment of the requirements for the
degree of Master of Arts in Physical Education.
over 1 inch (2.5 cm) which is very large clinically.14
t Mr. Bandy is presently on the faculty of the University of Central
It is suggested from the literature that minor
Arkansas, Little R W ~ AR.
,
$Dr. Sinning is a professor of Physical Education and Director of the
deviations
from a normal
running
gait due to LLD
Applied Physiology Research Laboratoryat Kent State Un~versity,Kent,
OH.
may severely handicap the athlete's ability to per173
174
JOSPT Vol. 7, No. 4
BANDY AND SINNING
form and be predisposing to further injury.7s10
However, there is little biomechanical evidence as
to what these deviations are, what specific
changes occur with the addition of a heel lift, and
if the addition of the heel lift is indeed advantageous to efficient locomotion.
The purpose of this study was to investigate
bilateral changes in range of motion, duration, and
angular velocity of the hip, knee, and ankle during
the swing and support phase when a heel lift,
which is inserted into the shoe of the short limb
in order to correct a LLD in an effort to produce
symmetrical movements, is removed. Potential
changes in gait patterns were examined while
walking (3 mph) and jogging (6 mph) on the treadmill.
METHODS
was asked to stand erect with his bare feet facing
forward, shoulder width apart, knees held in full
extension, and hindfoot in the neutral position.
The LLDs of the subject were measured with a
Pelvic Level (J. A. Preston Corp., 60 Page Rd.,
Clifton, NJ 07012). The Pelvic Level was positioned on the superior aspect of the subject's iliac
crest with the bubble in the leveling device showing tilt in the subjects with a LLD. Calibrated
blocks were placed beneath the heel of the short
side until the crests were level, as indicated by
the bubble on the leveling device moving to the
center. The width of the blocks needed to level
the crests was considered the amount of LLD the
subject possessed. The subject was then given a
heel lift of Pelite (Alimed Co., 68-70 HarrisonAve.,
Boston, MA 02111) material structured to equalize the LLD and placed in the shoe of the short
limb.
Subjects
Four male volunteers having a LLD between
3 / 1 ~ inch (0.48 cm) and 343 inch (0.95 cm) served
as subjects for this study. All subjects had worn
a heel lift for more than 1 year and for the purposes of this study were defined as "experienced"
heel lift users. Descriptive data are presented in
Table 1.
The criteria for LLD used in this study are that
the subjects present with the following characteristics on the short limb side: I ) low anterior superior iliac spine, 2) low posterior superior iliac
spine, and 3) low iliac crest. A LLD between 3 / 1 ~
and 343 inch was chosen because this difference
is large enough to cause lower extremity asymmetry that can be accurately measured, but not
so large that a correction beyond a heel lift is
necessary. Subotnick14 suggested that forefoot
control is necessary with an orthotic device to
correct a difference greater than 1/2 inch (1.3 cm),
and a heel lift alone does not supply enough foot
control. In order to measure LLD, each subject
Equipment
Six electrogoniometers (elgons) were attached
to the subject at bilateral hip, knee, and ankle
joints. An elgon is an instrument which uses electrical circuitry and recording devices to make a
continuous record of joint movement. Several
types of elgons have been designed for use with
the different joints. The one used in this investigation is similar to the universal elgon described
by Adrian et al.' A Wheatstone Bridge was used
to balance the circuits and calibrate the output.
Data were recorded by a model 1600 Strip Chart
Recorder manufactured by the MFE Corp.
PROCEDURES
Data Collection
Subjects reported to the testing area wearing
shorts and rubber soled running shoes. All subjects had previous experience with the treadmill
TABLE 1
Individual subject data
Subject
Age
Weight
Height
LLD
%a inch
0.48 cm
3/s inch
0.95 cm
l/4
inch
0.64 cm
% inch
0.64 cm
Leg
Time of
heel lift use
Right
13 months
Left
36 months
Right
18 months
Right
29 months
JOSPTJanuary 1986
HEEL LIFT FOR LOWER LIMB LENGTH DIFFERENCES
\
Fig. 1 . Subject on treadmill with six elgons attached to both
limbs.
c DIRECTION OF PAPER TRAVEL
175
for slightly more competitive athletes during their
training runs).
Six elgons were attached to both limbs at the
hip, knee, and ankle joints according to procedures described by Adrian et al.' (Fig. 1). These
instruments were attached with velcro straps and
reinforced with adhesive tape. Before testing, the
subject stood in an erect position and elgon recordings were made to establish a reference position for proper analysis of the recordings while
the joints were moving. In order to ensure that no
elgon displacement occurred during testing, the
reference position of the elgon was recorded
again following testing. Adrian et al.' have shown
that the elgon measures joint angles with less
than 3% error when attached by experienced
operators. Each subject walked and jogged on
the treadmill twice, once with the heel lift and once
without while the recording was being taken.
Data Analysis
HIP
E
KNEE
F
I
ANKLE
H
v
K
v
v
v
v
v
Fig. 2. A typical elgon tracing for one limb taken while running
at 6 mph. A downward tracing indicates flexion; an upward
tracing, extension. Specific points measured are: A, maximum
hip extension; 6,maximum hip flexion; C, maximum knee
extension, swing phase; D, maximum knee flexion, support
phase; E, maximum knee extension, support phase; F, maximum knee flexion, swing phase; G, ankle plantarflexion at end
of swing phase; H, maximum ankle dorsiflexion, support phase;
I, maximum ankle plantarflexion, support phase; J, maximum
ankle dorsiflexion, swing phase; K, foot contact.
and were given the opportunity to walk and jog
at the experimental speeds (3 and 6 mph) until
they felt comfortable. These speeds were chosen
because they represent a "normal" walking speed
and are within a range that might be used when
jogging in a physical fitness class (or even used
From the elgon recordings (Fig. 2), information
was obtained from each joint. Measurements included maximal flexion and extension (mean angles) during support phase and swing phase of
the knee and ankle. Maximal flexion is the joint
angle at the termination of flexion and beginning
of extension; maximal extension is the converse.
The swing phase is the position of the stride
during which foot swings free of support. The
support phase is when the foot is on the surface
and begins with heel strike and ends with push
off. Maximal flexion and extension of the hip was
also examined.
In addition, the amplitude of movement (or total
range of motion) which is the difference between
maximum flexion and maximum extension was
measured. The following movements were examined for the knee and ankle: 1) swing extension, 2) support flexion, 3) support extension, and
4) swing flexion. Only the total amplitude of movement for flexion and extension were examined for
the hip.
Also, the duration of each movement, which is
time required to move from one maximum angle
to the other, was computed for the hip, knee, and
ankle from the horizontal travel speed of the recording paper. Angular velocity was also computed. This computation gave an average value
for complete movement since no allowance is
made for the positive and negative accelerations
at the beginning and end of the movements.
Statistical analysis utilized the analysis of vari-
JOSPT Vol. 7,No. 4
BANDY AND SINNING
Short Limb
--------
Long Limb
Degrees
of
Motion
Without
With
Use o f H e e l L i f t
Fig. 3. Interaction effect of lift x limb for angle of maximum extension of the hip. All differences between the short limb and long
limb were significant. However, differences for each limb with and without the lift were not significant.
ance (ANOVA) with repeated measures. The Tukey HSD Test was used for post hoc analysis.
Significance was accepted at p < 0.05.
RESULTS
No significant differences were found due exclusively to the use of the heel lift for any dependent variables. However, there were interactions which were found to be significant. The
interaction between heel lift (with and without) and
limb (short and long) was significant for the angle
of maximum hip extension (F = 25.31, p < 0.01),
the range of motion of the swing plantarflexion
phase of the ankle (F = 14.31, p < 0.03), and the
range of motion of the swing flexion phase of the
knee (F = 180.24, p < 0.001). These interactions
are graphed in Figures 3 through 5.
DISCUSSION
Although no significant differences were found
due exclusively to the use of the heel lift for any
of the measures in the study, significant interactions were found. These interactions indicated
trends toward symmetry of movement with the
insertion of the heel lift for the angle of maximum
hip extension and the range of motion of the swing
plantarflexion phase of the ankle. The interactions
indicated a trend toward asymmetry of movement
with the insertion of a heel lift upon range of
motion of the swing flexion phase of the knee. No
other measurements related to the experimental
question ihvestigating biomechanical changes
due to the insertion of a heel lift to correct LLD
were significant.
These results differ from the only other investigation on the kinematic changes in gait due to
LLD by DeLacerda and Wickoff .2 The difference
may be due to several reasons. The study by
DeLacerda and Wickoff used only one female
subject and based any conclusions from the investigation on that single subject. In addition, the
JOSPTJanuary 1986
HEEL LIFT FOR LOWER LIMB LENGTH DIFFERENCES
Short Limb
--------
Without
Long Limb
With
Use o f H e e l L i f t
Fig. 4. Interaction effect of lift x limb for range of motion of swing plantarflexion phase of the ankle. Differences between short
limb with lift and long limb no heel lift, and between short limb no lift and long limb no lift were significant.
subject had a LLD of 3.18 cm (1.25 inches) while
all the LLDs in the present study were'less than
1 cm (Y2 inch). Last, DeLacerda and Wickoff
measured kinematic changes at a walking speed
(3 rnph) while the present investigation also incorporated a faster speed (6 mph).
There are three limitations of the design of this
study. The first is that the number of subjects is
small. A greater number of subjects would be
expected to reduce the variability and increase
the probability of finding significant differences.
This is especially significant in regard to the cases
where post hoc tests did not support the significant F ratios for interaction. Second, even though
all four subjects were young, active males with a
LLD who had worn a heel lift for over 1 year, they
differed in their activity level. Two of the subjects
were actively engaged in a running program jogging 3-5 miles, 4-5 times a week. The other two
subjects were active in sports such as biking,
softball, and soccer and were not involved in a
consistent jogging program. Further research utilizing a larger number of subjects and a more
specific population (trained subjects) may lead to
different results.
A third limitation of the present investigation
was that all the measurements were taken in a
sagittal plane of the lower extremity. No attempt
was made to measure rotation of the long axis of
the limb or movements in the transverse plane
which occur during gait such as tibia1 rotation and
pronation-supination of the foot. While very few
significant differences were obtained in this study,
further investigations incorporating the rotary
components of movement may lead to interesting
findings.
CONCLUSION
1) The addition of a heel lift to the short limb
did not appear to significantly affect the biome-
JOSPT Vol. 7, No. 4
BANDY AND SINNING
Short Limb
--------
Long Limb
Hith
Without
Use of H e e l L i f t
Fig. 5. Interaction effect of lift x limb for the range of motion of swing flexion phase of the knee. All differences between short
limb and long limb were significant. However, differences for each limb with and without the lift were not significant.
chanical measures of maximal flexion and extension during support and swing phase, range of
motion, duration of movement,and angular velocity of the hip, knee, and ankle while walking (3
mph) and jogging (6 mph) on the treadmill.
2) Insertion of a heel lift did tend to cause more
angleOf
symmetrical movement for the
hip extension and range of motion of the swing
~lantarflexionphase of the ankle, but more asymrange of motion of the swing flexion
phase of the knee.
metrical
Implications
It would appear reasonable to employ a heel lift
a trial basis for the treatment of symptoms
possibly related to LLD, but it is important to
Iealize
that all subjects do not respond'to the use
Of a heel lift in the same way.
it is
imperative that treatment with a heel lift be indiOn
vidualized to each subject and that frequent monitoring of the subject's response is mandatory.
in
p~~~r~t~'~,";~,"~~s and Don
their assistance
REFERENCES
~
-
- ~ - -
1. Adrian M. Tipton M. Karpovich YP: Electrogoniometry Manual.
Springfield, MA: Springfield College, Physiological Research L a b
oratow (Mimwraphed). 1965
2. De~a&rda~ ~ , ~ i c k0:o Effect
f f of lower extremity asymmetry on
the kinematics of gait. J Orthop Sports Phys Ther 3:17-20, 1982
3. DuPlessis MP: Stress fractures and overuse syndrome. S Afr Med
J 58:670. 1980
4. Fisk JW, Biagent MC: Clinical and radiological assessment of leg
lenqth. N Z Med J 81:477-480, 1975
5. Gross RH: Leg length discrepancy, how much is too much?
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6. Hult L: The Munkfors investigation. Acta Orthop Scand (Suppl16)
24:30-31,1954
7. James SL, Bates BT, Osternig LR: Injuries to runners. Am J Sports
Med 6:40-50,1978
8. Klein K, Buckley J: Asymmetries of growth in the pelvis and legs
of growing children. Am Correct Ther J 22:53-55, 1968
JOSPTJanuary 1986
HEEL LIFT FOR LOWER LIMB LENGTH DIFFERENCES
9. Klein K: Progression in pelvic tilt in adolescent boys from elementary through high school. Arch Phys Med Rehabil54:57-58, 1973
10. Mann RA, Baxtel D, Lutter L: Running symposium. Foot Ankle
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11. Pearson WM: Progressive structural study of school children. J
Am Osteopath Assoc 51:155-157, 1951
12. Redler I: Clinical significance of minor inequalities in leg length.
New Orleans Med Surg J 104:308-312, 1952
.
179
13. Subotnick SI: The short leg syndrome. J Am Podiatry Assoc
66:720-723,1976
14. Subotnick SI: Limb length discrepancies of the lower extremity (the
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