Cast and Bandaging Techniques

Plaster bandages and splints are made by impregnating crinoline with plaster of paris [CaSO₄)₂H₂O].
When this material is dipped into water, the powdery plaster of paris
is transformed into a solid crystalline form of gypsum, and heat is
given off:

The amount of heat given off is determined by the amount of plaster applied and the temperature of the water (3,4).
The more plaster and the hotter the water, the more heat is generated.
The interlocking of the crystals formed is essential to the strength
and rigidity of the cast. Motion during the critical setting period
interferes with this interlocking process and reduces the ultimate
strength by as much as 77%. The interlocking of crystals (the critical
setting period) begins when the plaster reaches the thick creamy stage,
becomes a little rubbery, and starts losing its wet, shiny appearance.
Cast drying occurs by the evaporation of the water not required for
crystallization. The evaporation from the cast surface is influenced by
air temperature, humidity, and circulation about the cast. Thick casts
take longer to dry than thin ones. Strength increases as drying occurs.

Plaster is available as bandage rolls in widths of 8, 6, 3, and 2 inches and splints
in 5- × 45-inch, 5- × 30-inch, and 3- × 15-inch sizes. Additives are
used to alter the setting time. Three variations are available.
Extra-fast setting takes 2 to 4 minutes, fast setting takes 5 to 6
minutes, and slow setting takes 10 to 18 minutes.

Advantages.
These materials are strong, lightweight, and resist breakdown in water;
they are also available in multiple colors and patterns.

Disadvantages.
They are harder to contour than plaster of paris, and the polyurethane
may irritate the skin. Fiberglass is harder to apply, although the
newer bias stretch material is an improvement. Review in detail the
instructions from each manufacturer before using the casting materials.
Patients are commonly under the impression that fiberglass casts can be
gotten wet. This is incorrect; if submerged, they need to be changed to
avoid significant skin maceration.

Webril has a
smooth surface and less tendency for motion within the thickness of the
padding than some of the other padding materials. It requires the most
practice to achieve a smooth application, however.

Specialist is
softer than Webril and contains wood fiber. It has a corrugated
appearance, and there is more tendency for sliding to occur within the
material. It is easier to apply without wrinkles than Webril, but it
becomes very hard if caked with blood.

Sof-Roll is a
soft padding similar in appearance to Webril but slightly thicker. It
has greater tear resistance and is therefore easier to stretch.

Felt or Reston
should be used to pad bony prominences and for cast margins. When
padding over bony prominences, such as the anterior superior iliac
spine, make a cruciate incision in the felt for better contouring.

Moleskin adhesive can be used to trim cast margins.

Use a clean bucket. Plaster residue and other particles in the water can alter the setting time.

Gloves keep
hands clean and prevent dry skin if one applies many casts. They also
make a smoother finish than is achieved by bare hands. They are
mandatory for working with fiberglass materials.

Shoe covers and aprons or gowns keep shoes and clothes clean to prevent one from appearing sloppy in plaster-covered attire.

Use appropriate draping to maintain the dignity of the patient as well as to keep plaster off all areas not casted.

Cast spreaders
are used to open the cut edges of a cast for access to underlying cast
padding, which is then cut with scissors. Spreaders come in various
sizes for large and small casts.

Cast knives
have sharp blades, and preferably have large handles for better
control. Sharp blades are essential; therefore, most practitioners
prefer to use no. 22 disposable surgical blades.

Cast benders adjust cast edges to relieve skin binding and pressure.

Cast dryers
blow warm to hot air around a plaster cast. They are generally not
necessary. An exposed cast and a fan work just as well and are safer.
Cast dryers can burn skin and tend to hasten the drying time of the
outer layers only.

To immobilize
fractures, dislocations, injured ligaments, and joints; to provide
relief from pain caused by infections and inflammatory processes; and
to facilitate healing

To allow earlier ambulation by stabilizing fractures of the spine or lower extremities

To improve function
by stabilizing or positioning a joint, such as for wrist drop after a
radial nerve injury, which also allows more useful hand function

To correct deformities, as in serial casting for clubfoot or joint contractures

To prevent deformity resulting from a neuromuscular imbalance or from scoliosis

The patient is informed of the procedure and instructed in whatever cooperation is necessary.

The surgeon or cast technician must have clearly in mind what to do and what will be required
(the position of the patient and assistants, how many rolls of plaster
will be needed, tools to trim the cast edges, etc.). All material and
equipment required to do the job properly should be assembled. (Once
cast application starts, it is difficult to stop and obtain something
that was forgotten.) The patient’s position must be comfortable and
must allow the surgeon and assistant to apply the cast expeditiously.
Special maneuvers required to perform and hold the reduction are
rehearsed.

A circular cast should not be used in fresh trauma or postoperatively when one anticipates swelling, unless the cast is bivalved or split initially and provisions are made for adequate observation.

If unexpected swelling occurs in a circular cast, bivalve or split the cast immediately all the way to the patient’s skin as described in IV.B and C.

Unless specifically contraindicated, clean
the part to be casted with soap and water, then dry it with alcohol.
Apply the cast over a single layer of cast padding with edges of the
material minimally overlapping. Protect unusual bony prominences with a
1/4-inch felt or foam rubber padding.

Dip the plaster or fiberglass rolls in water
by placing them on end, which allows air to escape and results in
complete soaking of the plaster. The bandages are sufficiently soaked
when the bubbling stops. They can be left in the water up to 4 minutes
without decreasing the strength of the cast, but the setting time
decreases the longer they are immersed. Therefore, for maximum working
time, remove bandages soon after the bubbling stops. Lightly crimping
the ends of the plaster bandages helps prevent telescoping of the roll.

Except for very large casts (e.g., body casts, spicas), all plaster bandages should be dipped and removed from the water at the same time.
Thus, all the plaster in the cast is at the same point in the setting
process. This scheme maximizes the interlocking of the crystals between
the layers of plaster, thereby maximizing the strength of the cast. In
addition, delamination between the bandages is decreased.

Use cool water for larger casts when more time is needed to apply all the plaster or fiberglass, and use warm water for smaller casts or splints. Never use hot water because enough heat can be generated to burn the patient (8).
Similarly, do not place limbs with fresh casts onto plastic-covered
pillows; these tend to hamper heat dispersion significantly and may
result in burning. If the patient complains of burning, it is prudent
to remove the cast immediately and reapply using cooler water.

Keep the plaster bandage on the cast
padding, lifting it off only to tuck and change directions—that is, to
push the plaster roll around the patient’s body or extremity. Use the
largest bandages, usually 4- and 6-in. bandage rolls, that are
consistent with smooth, easy applications. Using large bandages allows
the fastest application of plaster and provides sufficient time for
molding before the critical setting period. Six or seven layers of plaster
or two to three layers of fiberglass usually are sufficient, except in
individuals who are particularly hard on casts. The cast should be of
uniform thickness (seven layers or

1/4
in.). Avoid concentrating the plaster about the fracture or the middle
of the cast. Avoid placing two circumferential rolls directly on top of
each other while wrapping the plaster on the patient’s extremity.
Reinforce casts where they cross joints by incorporating plaster or
fiberglass splints longitudinally. Incorporate reinforcing plaster
splints into body and spica casts as described later in this chapter (III.B and C).

During application of the cast, turn the padding back at the edges of the cast and incorporate it.
Another method of finishing the edges is to turn back the padding after
the cast has set and to hold the padding down with a single, narrow,
plaster splint; a row of ordinary staples; or moleskin.

Apply all the material rapidly
so there is time to work and mold it before the critical setting
period. The cast should have a sculptured look, not only for cosmetic
reasons but also for comfort. If the fracture is to be stabilized by
the three-point fixation principle, it is more important to maintain
the three forces of pressure on the cast during the critical setting
period than to have a perfectly smooth surface on the cast. This step
is more difficult for fiberglass casts.

Once the critical period of interlocking of crystals begins, molding and all motion should stop until the material becomes rigid. Otherwise, the cast is weakened considerably.

After the cast sets and becomes rigid, trim the edges
using a plaster knife or cast saw. Use the knife by supporting the
cutting hand on the cast and pulling the portion of the plaster to be
trimmed up against the knife blade rather than blindly cutting through
the plaster and possibly cutting the patient. If the cast is too thick
or hard, an oscillating cast saw is preferred.

Apply forearm casts to allow full 90 degrees flexion of all metacarpophalangeal joints and opposition of the thumb to the index and little fingers.

Extend leg casts
to support the metatarsal heads but not to interfere with flexion and
extension of the toes. This rule is invalid when the toes need support
(as with fractures of the great toe or metatarsals) or when there is a
motor or sensory deficit. In these situations, the cast is extended as
a platform to support and protect the toes. Place a 1/2-inch piece of
sponge rubber beneath the toes and incorporate it into the plaster for
walking casts, or supply the patient with a commercial cast shoe.

Immobilize as few joints as possible, but as a general rule, one immobilizes the joint above and below a fresh fracture.

Lower extremity.
Usually make posterior plaster splints in the lower extremity by
applying a standard cast (knee cylinder, short-leg, or long-leg, cast,
as described in III. D, E, F)
and then bivalving the cast and retaining only the posterior shell.
Hold the posterior splint to the leg with bias-cut stockinet or an
elastic bandage wrap. Alternatively, use 5- × 30-in. posterior and
medial/lateral splints, leaving the anterior aspect of the leg covered
only by soft roll.

Apply the basic body jacket
over large tubular stockinet. Place 1/8- to 1/2-in. felt pads over the
shoulders (if suspenders are used), costal margins, iliac crests
including anterior iliac spine, and the dorsal spine. Make a cruciate
cut in the felt placed over the crests to distribute pressure uniformly
over the bony prominence. Apply a single layer of plaster snugly over
the padding. Splints may be used, as shown in Fig. 7-2.
If suspenders are required, make a “V” with 5- × 30-in. splints. Place
the point of the “V” between the scapulae and bring the ends over the
shoulders. Snugly apply rolled plaster over the splints and mold.
Usually extend the jacket posteriorly from the top of the sacrum to the
inferior angle of the scapulae and anteriorly from the symphysis pubis
to the sternal notch. Body jackets may be applied with the lumbar spine
in flexion or extension as well as the neutral position. For
hyperextension body jackets, often used in thoracolumbar fractures, use
the Goldwaithe iron apparatus for positioning, as in Fig. 7-3.

The Minerva body jacket
is named after the goddess Minerva, who sprang forth from Jupiter’s
head when it was cleaved by Vulcan in an attempt to relieve Jupiter’s
headaches. Minerva appeared chanting a triumphant song and wearing a
large metal headdress. The Minerva body jacket incorporates the skull
and is used to immobilize the cervical spine; its most frequent
application is in children. This type of jacket is applied in the same
manner as the body jacket but also calls for the following steps. Place
a fluted felt pad around the entire neck, with the neck halter traction
over the padding. Tie the halter straps at ear level to prevent the
halter’s slipping off the head. Place another felt pad along the length
of the spine and the occiput. Wrap the rest of the head with 3-in.
sheet cotton padding. At least two operators are necessary for even
application of the plaster, one for the head and one for the body. Roll
3-in. plaster bandages about the head and neck. Apply narrow splints
around the chin, neck, occiput, and forehead. Use wide splints all the
way from the sacrum to the occiput, with another wide splint extending
from the chest to the chin. Incorporate these splints into the cast by
snugly wrapping plaster bandages over them. Then mold together the
plaster about the head, neck, and body at the same time. Carefully mold
beneath the mandible. Cut the plaster in a “V” to release the chin and
also cut out about the ears and the face (Fig. 7-4,
inset). Trim the plaster above the jaw line and leave the eyebrows
exposed. A Minerva body jacket is useful in children and when cervical
or halo vests (Fig. 7-4) orthoses are not appropriate.

Pad a bilateral short-leg (panty) spica
in much the same way as for the body jacket but include the legs. These
casts are generally applied on fracture tables (adults) or spica boards
(children). Use tubular or bias-cut stockinet. Pad bony prominences
with 1/8- to 1/2-in. felt with cruciate incisions. Apply plaster or
fiberglass to the upper portion of the cast as is done with the body
jacket. Reinforce the hips with splints as shown in Fig. 7-7.
Apply plaster or fiberglass well next to the perineal post under the
sacrum to avoid weakness in the area (the intern’s triangle). Snugly
tie the splints in with plaster or fiberglass bandage rolls extending
to the supracondylar portion of the femurs. Mold the material well over
the iliac crests. The patient may be lifted from the table with the
sacral rest still in the plaster. Turn the patient on his or her
abdomen and cut out the sacral rest. Trim the edges of the cast in the
usual manner.

Examples of long-leg hip spicas are shown in Fig. 7-8.
Apply the leg portion of the cast like any other long-leg cast, using
the special splints about the hips as described for the short-leg
spica. Support the casted extremities with struts. These are usually
made of wooden stakes (1/4 × 2 in. or 3/4 × 1/2 in.) or

dowels.
Cover with plaster or fiberglass and attach them to the casted
extremity by wrapping a bandage in a cordlike figure-of-8 fashion about
the strut and cast; then roll the bandage around the strut and cast to
create a well-molded cast. Sedate or anesthetize infants and small
children before spica cast application; they are generally applied in
the operating suite.

Apply the shoulder spica
with the patient standing or supine on a spica table that has a
metallic backrest. The arm may be supported with finger traps, or, with
a cooperative patient in the sitting or standing position, the cast may
be applied while an assistant holds the arm. The principles of padding
and cast application for body jackets and long-arm casts are combined
to produce a shoulder spica. In addition to the splints normally used
for body and long-arm casts, apply a wide splint from the lateral
chest, up under the axilla, to the medial side of the arm. Place other
splints across the posterior aspect of the arm, over the shoulder, to
the opposite side. Tie in the splints with rolled plaster or fiberglass
and place a strut between the arm and trunk.

Apply the short-leg cast
with the patient sitting on the end of a table with the knee flexed 90
degrees. Alternatively, apply it with the patient supine, the hip and
knee flexed 90 degrees, and the leg supported by an assistant. The type
of padding matters little, except that Webril and stockinet tend to
shear less and therefore may allow for a tighter cast over a longer
period of time. Use only one layer of padding except over the malleoli,
where extra padding frequently is required. For most casts, have the
ankle in a neutral position. Two plaster bandages usually are required,
and the width selected (3, 4, or 6 in.) varies with the size of the
patient. Fold 4-in. splints longitudinally in half, and place one
splint on all four sides of the ankle for reinforcement before applying
the second plaster bandage. Extend the cast distally from the
metatarsophalangeal joints and proximally to one finger breadth below
the tibial tubercle. Trim the edges and pad as previously described.

If desired, a walking cast
may be made with either a rubber rocker walker or a stirrup walker.
Place either one in the midportion of the longitudinal arch of the foot
in line with the anterior border of the tibia. With a rocker walker,
the medial longitudinal arch is filled with plaster splints to make a
flat base. Then the walker is secured with a third plaster bandage.
Commercially available walking shoes (or boots), which fit over the
casted foot, are more widely used. A flat plaster base on the plantar
aspect of the cast is required for these shoes. If the ankle must be
held in equines (such as required for cast treatment of an Achilles
tendon rupture), a stirrup walker is advantageous, and the patient’s
opposite shoe should be adjusted to the appropriate height for walking.
All walking casts should dry for at least 24 hours prior to weight
bearing.

First apply a short-leg cast as described earlier (III.E).
Then extend the knee to the position desired and continue the cast
padding to the groin. Two 6-in. plaster or fiberglass bandages usually
are required for the upper portion of this cast except in patients with
heavy thighs. After the first bandage is applied, fold 4- or 5-in.
splints longitudinally and place them medially and laterally across the
knee joint for reinforcement. After the second plaster or fiberglass
bandage is applied, mold the cast medially and laterally in the
supracondylar area to help prevent the cast from slipping distally when
the patient begins to stand.

The long-leg walking cast is made as described in III.E.2, but the knee must be flexed no more than 5 degrees.

The cast treatment programs made popular by Dehne and Sarmiento (see Selected Historical Readings)
are designed to allow early weight bearing of a fractured tibia. The
affected leg is placed in a very snug cast that maintains the tissue
and fluids of the leg within a rigid container. Shortening is prevented
by the hydraulic principle that fluids are
not compressible. Thus, the patient can bear weight soon after a
fracture without excessive further shortening, and fracture healing is
benefitted by the improved vascularity derived from ambulation. The
advocates of these casting techniques describe a “total contact cast.”
The authors believe, however, that all casts to the lower extremities
should be total contact casts.

The long-leg total contact cast as described by Dehne is applied like a long-leg walking cast with only minor modifications.

The below-the-knee total contact, or patellar tendon-bearing, cast is applied much as a regular short-leg walking cast is, with the following modifications (Fig. 7-9):

The authors believe
that a long-leg weight-bearing cast is easier and safer (in regards to
skin and fracture complications) for most individuals to apply than the
below-the-knee total contact cast. Comparing the treatment
results published in the literature provides no evidence that one
technique is superior to the other. The theoretic advantage of
providing knee motion with the Sarmiento technique is offset by the
expertise required to apply this cast properly.

Begin weight bearing
at 24 to 36 hours after plaster cast application when the patient can
tolerate it; patients with fiberglass casts can be encouraged to weight
bear 3 to 6 hours after casting.

A cast-brace
is a casting device for the treatment of fractures of the distal femur
or tibial plateau, which are not considered appropriate for operative
management, generally in high-risk patients. Occasionally a cast-brace
is applied after 1 to 3 weeks of traction, with the patient remaining
in the hospital for a short period after the brace is applied. Thus,
the hospital stay can be as long as 2 to 4 weeks. In addition, this
technique allows mobility of the knee during the healing phase, so less
physical therapy is needed to regain knee motion when the fracture is
healed. These devices have generally been replaced by commercially
available hinged knee braces.

In removing or splitting casts, use the oscillating saw.
Reassure the patient by giving a cast saw demonstration before actually
cutting the cast. Stabilize the hand holding the electric saw on the
cast, and push the blade through just the plaster with short repetitive
strokes, as shown in Fig. 7-10. Avoid bony prominences as the cast saw can cut into the skin over them.

Windows may
be cut from the cast to expose wounds. The windows must be replaced,
however, and rewrapped with either a new plaster or an elastic bandage
to prevent local edema.

Use adhesive strapping
(taping) for the possible prevention and treatment of athletic
injuries. Use strips of adhesive tape instead of one continuous winding.

Bandaging
(wrapping) uses nonadhesive materials (gauze, cotton cloth, and elastic
wrapping) in the treatment of athletic injuries. Employ one continuous
unwinding of material.

Skin reactions. Most tape reactions are mechanical,
not allergic. Allergic reactions are characterized by erythema, edema,
papules, and vesicles. Test for an allergic reaction by patch testing.
If the test is positive, the above signs manifest themselves within 24
to 48 hours.

The medicated bandage (Unna boot) contains zinc oxide, calamine, glycerine, and gelatin and usually is indicated
for lower extremity areas of skin loss that require protection and
support. This type of support dressing prevents edema and allows
ambulation in patients with known venous conditions at the time of cast
removal.

While the cast is still on,
range-of-motion exercises of the adjacent joints not immobilized and
isometric exercises for the immobilized muscles (e.g., weight bearing
in a cast) serve both to improve nutrition and to decrease atrophy of
articular cartilage, bone, and muscle. Edema and the rehabilitation
required after cast removal are also minimized.

Warn the patient that after removal of any cast from a lower extremity, some swelling is normal.

Once the cast is removed, an elastic stocking or bandage is desirable for support.

Between these two groups
is a considerable degree of overlap. If it is anticipated that a
complicated and often incomplete open reduction and internal fixation
is not secure enough to allow early movement of the joint, then it may
be better to treat the fracture nonoperatively. The objective is the best possible final range of movement.