The Effectiveness of
Four Contemporary
Cervical Orthoses in
Restricting Cervical
Motion
Thomas R. Lunsford, MSE, CO
Michael Davidson
Brenda R. Lunsford, MAPT, MS
ABSTRACT
The cervical motion in three planes was
evaluated in 10 subjects while they wore
each of four contemporary cervical collars (Philadelphia, Miami J, Malibu
and Newport Extended Wear) and no
orthosis. The amount of force placed on
the orthosis by the subject was controlled and monitored. The cervical motion was measured using three video
cameras and a pointer attached to a
mouth stick that was fitted over the lower teeth of each subject. The subjects sat
in a custom-built chair and were secured
by thoracic and pelvic straps to minimize extraneous motion.
The Malibu collar provided the greatest restriction in coronal flexion, sagittal
fiexion, sagittal extension and axial rotation (4], 40, 57 and 61 percent, respectively). Each of the four orthoses
allowed significantly less motion than
"no orthosis" at all for the motions evaluated.
Introduction
The earliest evidence documenting the
use of cervical orthoses for relieving
pain and correcting deformity came
from the Fifth Egyptian Dynasty
(2750-2625 B.C.) (1). The biomechanical principles used today can be traced
directly to devices used by Hippocrates
and his successors through the armorers of the Middle Ages to the present
(2). Today a wide variety of cervical
orthoses is available, known by an eponym of the inventor's name (e.g., Benjamin-Taylor, Thomas, Guilford), the
locality where they were designed (e.g.,
Philadelphia, Yale, Newport, Malibu,
Miami) or by descriptions (e.g., four-poster, two-poster, sternal occipital
mandibular immobilizer [SOMI]).
The use of cervical orthoses falls primarily into three categories: motion restriction to protect or prevent pain,
motion restriction to protect spinal instability pre- and postsurgery, and
emergency protection immediately following trauma (3). Such orthoses are
used to provide support and protection
as well as limit range of motion. Due to
an array of pathological conditions and
factors, many design variations and
types of cervical orthoses are available
to the practitioner (4).
Pain
In the past few decades, the soft foam
cervical collar, normally associated
with the treatment of "whiplash," has
evolved into a variety of cervical orthoses using combinations of rigid and
flexible materials to restrain cervical
motion. The objective of the cervical
orthosis following any type of injury to
the soft tissues of the cervical spine is
primarily to restrict motion to allow
soft tissue healing by reducing the demand on the muscles and to prevent
pain by avoiding extremes of motion.
This evolution has been championed
by physicians and orthotists who were
dissatisfied with cervical immobilization in the rehabilitation setting where
the objectives of motion restriction are
much greater.
Spinal Instability
Typically a severe cervical injury is
treated with a halo-vest orthosis or
with spinal surgery and then a halo-vest
orthosis (5). After several weeks, when
the osseus integrity of traumatized cervical vertebrae permits, the halo-vest
orthosis is removed and a less obtrusive
orthosis applied (e.g., Philadelphia
collar, soft collar, semi-rigid plastic
collar, etc.). The second, less restrictive orthosis might be worn for an
equal period of time or until the patient
is discharged (6).
Emergency
Independently, emergency care professionals, who are dedicated to extrication and transport of trauma victims,
have spurned a variety of cervical orthoses and extrication devices used not
only to immobilize but to control the
position (posture) of the cervical spine.
The emergency cervical devices have
tended to be more compact (for storage in emergency vehicles) and exhibit
ingenious creative design. Many of the
flat emergency collars can be transformed into adjustable, geometrically
sound cervical orthoses by twisting and
snapping them into place. Mostly due
to entrepreneurial forces, the simpler,
less expensive collars developed for
trauma victim immobilization and
transport inevitably have found application in the rehabilitation setting.
Shapiro et al. have reported that the
cervical spine produces a remarkably
large range of motion-145 degrees of
flexion and extension, 180 degrees of axial rotation and 90 degrees of lateral flexion (7). Kottke and Mundale (8) compared range of motion of the neck from
four documented sources and reported
the following as clinical guidelines: flexion (70 degrees +/- 10 degrees), extension (75 degrees +/- 10 degrees), lateral
bending (45 degrees +/- 10 degrees) and
axial rotation (75 degrees +/- 10 degrees). A cervical orthosis' purpose is to
restrict cervical motion (cervical spine)
and capital motion (head on spine). Depending on the objectives of the orthosis, selection can best be accomplished if
each collar available on the market has
documented its ability to restrict motion
in each plane.
Johnson and co-workers evaluated
the effectiveness of five cervical orthoses in restricting sagittal motion in
normal subjects using roentgenograms
and found the cervicothoracic orthosis
with rigid connections between the anterior and posterior components and
fixation to the chest to be superior (9).
Fisher et al. used roentgenographic
data to compare the polyethylene collar, Philadelphia collar, four-poster
and SOMI on normal subjects (10).
The four-poster and SOMI were found
to be significantly more restrictive.
Hartman's group used cinefluoroscopic data to compare the soft collar,
semi-rigid collar, four-poster cervical
orthosis and the Guilford two-poster
cervical orthosis in terms of motion restriction in all three planes of motion
and found the Guilford design to be
superior (11). There was no mention of
how range of motion was measured;
the sample size was very small; and no
statistical analysis of the data was performed.
In a similar study, Colachis et al.
compared sagittal motion restriction
using radiography of the soft collar,
chin piece collar and Queen-Anne collar in normal women using radiography
and found the chin-piece collar to be
significantly best (12).
Wolf and associates studied immobilization imparted by halo casts and halo
vests on patients with injured spines
(13). Their data showed that flexion
extension could be limited to 7.5 degrees (11.7 percent of normal), total
lateral bending to 4.1 degrees (8.4 percent of normal) and rotation to 2.2 degrees (2.4 percent of normal). These
results clearly distinguish the halo as
the most effective means for restricting
cervical motion in all three planes of
motion.
McGuire and associates compared
the Neclok and Stiff Nec emergency
collars with the more traditional Philadelphia collars in sagittal rotation (flexion-extension) and translation on C4-5
destabilized cadaver specimens while a
five-pound flexion force was applied.
They found no significant differences
in the collars' immobilizing power (14).
Kauffman et al. performed a similar
study whereby the Neclok collar was
compared to the Philadelphia and soft
collars using goniometry on normal
subjects. They found the Neclok was
significantly better in immobilizing the
cervical spine in all three planes of motion (15).
Huerta et al. compared 11 pediatric
cervical collars, both alone and in combination with commonly used supplemental devices (e.g., spinal boards),
on mannequins representing an infant
and a normal 5-year-old child and
found that none of the collars alone
provided acceptable immobilization
(17 degrees flexion, 19 degrees extension, 4 degrees rotation and 6 degrees
lateral motion) compared to 3 degrees
maximum for the combination of a rigid cervical orthosis and a rigid spinal
board (16).
Sagittal and coronal plane motion
restriction on normal subjects using
common extrication and transport devices were measured radiographically
by Graziano and co-workers, and the
XP-One collara, which splinted the
head and torso, was superior (17).
Cline and his group radiographically
studied the efficacy of seven methods
of cervical immobilization used in the
prehospital setting and found the short
board technique to be superior to all
collars (Philadelphia, Hare and rigid
plastic). They also found that the collars offered no augmentation to the
short board technique (18).
Podolsky's group compared motion
in all three planes in normal subjects
(supine) using goniometry and found
the Philadelphia collar in combination
with forehead tape and sandbags to be
the best method of immobilization
(19). No mention was made of the relative contribution of the tape vs. sandbags vs. Philadelphia collar.
The above orthoses' ability to restrain cervical and capital motion has
been evaluated by using both goniometry (10,19) and roentgenography (9,11,
14,17,18) in living subjects, cadavers
and mannequins. Fisher's group not
only compared four cervical orthoses,
but also demonstrated that goniometry
correlates closely with roentgenographically collected data when assessing overall cervical motion (i.e., Cl
through C7) (10).
When an orthosis needs to be worn
for an extended time, comfort is often
an issue. Therefore, restrictive efficacy
is often sacrificed (15). In this particular situation, the soft and semirigid collar types of cervical orthoses are usually the treatment of choice. A previous
study (20) has suggested most cervical
orthoses are loosened by the patient
because the practitioner has fit the device too "tightly." These results suggest the way an orthosis is fit "properly" is merely arbitrary and might vary
among practitioners.
Few previously published studies
have quantified the amount of force
exerted on the orthosis by the subject.
In some studies (9,17) the test subject
was instructed to exert as much force as
possible. In other studies (11,15,18,19)
the subjects used "active" force while
in another study (21) the subject relaxed into the orthosis. It is felt that
this subjectiveness creates inconsistencies and inconclusive results. Therefore, the amount of exertion by the
subject on the orthosis was controlled
and monitored in this study.
With the advent of cervical orthoses
that allow long-term periods of use, it
was felt necessary to investigate the effectiveness of these "newer generation" cervical orthoses.
Specific Objectives
The study's objectives were to
- measure sagittal flexion/extension, coronal flexion and axial rotation
of the cervical spine of 10 subjects with
pre- and post-video frames while wearing no orthosis and while wearing each
of the four following cervical orthoses:
- Philadelphia Collar
- Miami J Collar
- Malibu Collar
- Newport Extended Wear Collar
- monitor and control the amount of
exertion placed on the orthosis by the
subject and to control strap tension
when fitting each orthosis
- compare the mean end range of
motion for each of the four cervical
orthoses for each of the four planes of
motion.
MethodMaterials
The four cervical orthoses selected for
this study were the Miami J, Malibu,
Philadelphia and Newport collars (see
Figure 1
). These orthoses were procured for and fit on the test subjects
according to the manufacturers' specifications. Ten healthy female volunteers (21 to 49 years of age) were used
for this study. All volunteer subjects
were evaluated to ensure they had no
history of spinal injury, disease or limited cervical range of motion. The cervical orthoses were tested in a randomly selected order for each individual
subject.
Apparatus
To effectively measure the range of
cervical motion, three VHS Sony video
cameras were utilized. The three cameras were centered around a high-back
chair (see Figure 2
). Camera 1 was
placed in front of the chair to obtain a
coronal view of a subject sitting upright.
Camera 2 was placed at the subject's
right side to obtain a sagittal view while
camera 3 was placed above the subject's
head to obtain a transverse view.
To ensure consistency of fit, tension
values of the orthoses' adjustment
straps were controlled. By using an
elastic tensiometer, 2.3 Kg (5 pounds)
of force was exerted in a trial run then
used throughout the testing process.
The subjects wore a mouth piece
that fit over the lower teeth and was
attached to two needle pointers (see
Figure 3
). The first pointer was directed anteriorly from the subject's mouth
and was used in measuring axial rotation, sagittal flexion and sagittal extension. The second pointer was directed
superiorly from the subject's mouth
and was used to measure coronal flexion.
The range of motion in three planes
was measured by filming the subjects
using three video cameras. Images of
the maximum range-of-motion were
compared with those of neutral by
viewing individual frames displayed on
a television monitor. Range of motion
was measured by comparing the extremes of the center lines of the pointers with a precision protractor and then
calculating the resulting range-of-motion angles in degrees.
Procedure
Test subjects sat in a custom-built chair
and were secured by thoracic and pelvic restraints to minimize movement
inferior to the vertebral level of C-7
(see Figure 4
).
Each subject was fitted with a plastic
helmet that had a 6.25-mm (1/4-inch)
diameter eyebolt protruding 50 mm (2
inches) superiorly from the helmet and
one protruding 50 mm (2 inches) anteriorly (see Figure 5
). A 0.9-Kg (2 pound) weight was then attached to
the anteriorly pointing eyebolt for axial
rotation and to the superiorly pointing
eyebolt for sagittal flexion/extension
and coronal flexion. The subjects
were instructed to relax while the
weight pulled them into the corresponding planes of motion.
The four aforementioned motions
for each subject were measured while
wearing no orthosis and while wearing
each of the four randomly selected test
orthoses. Ten measures of each motion
for each subject were recorded. The fit
of each orthosis (see Figure 6
) was standardized by using an elastic tensiometer attached to the adjustment straps of
the orthosis and conforming to manufacturers' and previously set standards
of 2.3 Kg (5 pounds) to ensure consistent fit.
Sagittal Flexion
Sagittal flexion was measured in the
sagittal plane. The subject was asked to
look forward in a comfortable posture.
The position of the anteriorly directed
needle pointer was used to determine
neutral for sagittal flexion and extension. The camera produced images at
neutral (see Figure 7
) and at sagittal
flexion resulting from the predetermined load (see Figure 8
). Both positions were compared, and total range
of motion was calculated.
Sagittal Extension
Sagittal extension was measured in the
same manner as sagittal flexion and included neutral to full extension resulting from the predetermined load.
Coronal Flexion
Coronal flexion was measured in the
coronal plane by using the needle indicator that points superiorly from the
subject's mouth. On the video monitor
a line was delineated, bisecting the subject's face, cervical spine and sternal
notch. This line was used to reference
the neutral position and was compared
to maximum coronal flexion resulting
from the predetermined load to determine ranges of motion.
Axial Rotation
Axial rotation was measured by filming
the subject in the transverse plane. The
subject was asked to look forward in a
comfortable position. On the video
monitor, a line was delineated perpendicular to the shoulders to determine
neutral. Individual frames were taken
at neutral and at rotation resulting
from the predetermined load. The needle pointers in both positions were
compared to determine the resulting
range of motion while the subject wore
no orthosis and each of the four test
orthoses.
Data Analysis
Each subject performed all motions
with each of the four cervical orthoses
and with no orthosis. Each trial was
conducted 10 times. The mean and
standard deviation end range of motion for each orthosis was calculated.
Analysis of variance (ANOVA) with
repeated measures was used to test for
intra-subject variation. Two-way ANOVA was used to test for significant
differences between the orthoses in
each plane of motion. Post hoc
Scheme's analysis was conducted to isolate pairs of orthoses with significant
differences (p<.05).
The statistical computer program
Crunch was used to conduct all data
analysis.
Results
For each plane of motion tested, even
the least restrictive cervical orthosis
significantly reduced motion compared
to "no orthosis."
Coronal Flexion
The unrestricted motion of coronal
flexion, with 0.9 Kg (2 pounds) of applied force, had a mean arc of 58.0 degrees of motion (see Table A, Figure
9). The Malibu, Miami J, Newport and
Philadelphia collars allowed 34.3, 37.8,
42.7 and 45.3 degrees, respectively
(see Table A
, Figure 9
). The Malibu
collar had the greatest reduction (41
percent) in coronal flexion, significantly more restrictive than the other three
collars.
Sagittal Flexion
The unrestricted motion of sagittal
flexion, with 0.9 Kg (2 pounds) of applied force, had a mean arc of 69.7 degrees of motion (see Table A
, Figure 9
). The cervical orthoses fell into two
groups: the Malibu and Miami J, which
allowed 33 and 35.9 degrees, respectively, and the Philadelphia and Newport collars, which allowed 40.5 and
43.9 degrees, respectively. These two
groups of cervical orthoses were significantly different from each other and
from "no orthoses." The Malibu and
Miami J collars reduced sagittal fiexion
at least 50 percent while the Philadelphia and Newport collars reduced sagittal flexion by 40 percent.
Sagittal Extension
The unrestricted motion of sagittal extension, with an applied force of 0.9 Kg
(2 pounds), had a mean arc of 64.8
degrees of motion (see Table A
, Figure 9
). The Malibu was the most restrictive
and averaged 27.8 degrees, a 57 percent restriction, which was significantly
more restrictive than the other three
orthoses. The Philadelphia collar allowed 34.3 degrees, or 47 percent of
restriction, of normal range, which was
significantly less than the Miami J and
Newport orthoses.
Axial Rotation
The mean unrestricted motion of axial
rotation, with 0.9 Kg (2 pounds) of applied force, was 63.1 degrees (see Table A
, Figure 9
). The Philadelphia, Miami J and Newport orthoses allowed
just over 32 degrees of motion, a 51
percent restriction of normal motion.
The Malibu provided significantly
more restriction than the other orthoses, allowing an average of 24.7 degrees (61 percent).
Discussion
Four common cervical restraints, each
of which is categorized as a collar type
of cervical orthosis, were evaluated
and compared for their ability to restrict motion while the force exerted
against the collar was controlled. Although not as effective as the poster-type or halo-vest orthoses, this study
demonstrates that collar orthoses are
effective in limiting cervical motion (40
to 60 percent).
Each of the four orthoses allowed
significantly less motion than "no orthoses at all four motions evaluated.
The Malibu collar was the best cervical
orthosis in restricting motion in the
three planes evaluated. Additionally,
the Newport and Miami J showed no
significant difference in sagittal extension or axial rotation. All subjects tolerated the Philadelphia and Newport
well; however, many said that the Miami J caused discomfort over the manubrium upon sagittal flexion.
It should be noted, however, that
when the adjustment straps of the cervical orthoses were tightened to 2.3 Kg
(5 pounds) of tension, some subjects
mentioned how "confining" the Malibu, Miami J and Newport collars felt.
All subjects were able to tolerate the
cervical orthoses throughout the testing procedure, and a few suggested
that loosening the straps would be desirable.
There appears to be the age-old inverse relationship between comfort
and effectiveness of cervical orthoses
on normal subjects. Although some
discomfort comments were made
about all the orthoses, the more effective ones were more uncomfortable. In
some cases the discomfort was related
to strap tightness and in other cases to
the "confining" effect.
A study is recommended where cervical collars are evaluated under similar conditions and strap tension is varied from Ito 5 Kg (2.2 to 11 pounds)
with "comfort" measured subjectively
and motion restriction objectively.
The combination of cervical collar
and plastic helmet (with straps) may
have contributed to some of the subjects' discomfort. A future study
should consider an alternative to the
plastic helmet for controlling the subjects' exertion on the orthoses. Perhaps a simple headband at the equator
with attachment for the 0.9-Kg (2pound) weight would suffice.
Obviously this study evaluates only
the mechanical means by which cervical orthoses restrain cervical motion.
The neurological mechanism (i.e., kinesthetic reminder) should also be identified and evaluated. Perhaps wearing
time should also be a controlled variable since what begins as a tolerable
kinesthetic reminder could become uncomfortable over time, especially with
men whose beards increase the shear
friction between skin and the orthotic
liner or interface material.
This study shows the importance of
critical and objective evaluation of new
and old cervical orthoses. Additionally, this study demonstrates that effectiveness in restraining motion may
have to be sacrificed for comfort, especially in patients with less severe cervical distress. For now, however, only
the pure mechanical facts are known
and will remain untempered by comfort until further research is conducted.
If the cervical orthosis is to be used
for "pain," then adequate immobilization with maximum comfort should be
the criteria. However, if the cervical
orthosis is to be used when there is
spinal instability, then the criteria
should be maximum restraint of motion and static posture. Static posture
has not been addressed by the plastic
collars in comparison to the classic
four- and two-poster cervical orthoses.
THOMAS R. LUNSFORD, MSE, CO, is director of the orthotic department at The Institute of Rehabilitation and Research in Houston, Rexas, and assistant professor of physical medicine and rehabilitation at Baylor College of Medicine.
MICHAEL DAVIDSON is currently a board-eligible orthotist at Loma Linda University Medical Center, Loma Linda, Calif., and was a student at California State University when this research was conducted.
BRENDA LUNSFORD, MAPT, MS, is visiting professor at Texas Woman's University in Houston.
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