FRACTURE HEALING AND CLOSED TREATMENT OF FRACTURES AND DISLOCATIONS

Bone’s lamellar and osteonal structures direct crack
propagation in certain predetermined directions. The lamellar junctions
and cement lines of bone are weak, and they crack more easily than the
bulk of the material. These weak interfaces are oriented so that the
cracks travel along

and
around the bone, rather than directly across it. Energy that would
quickly break a bone is used in forming longitudinal or circumferential
cracks that do not cause failure and that can be repaired by remodeling
(50).

The material strength of bone differs in various modes
of loading. It is strongest in compression, weakest in shear, and
intermediate in tensile failure stresses. When a bone is fractured by
compression, it tends to fail along planes that carry the highest shear
stresses, which reach the failure level first; these planes typically
are at an angle of 45° to the load direction. When a bone is bent, the
highest stresses are tensile and compressive; failure begins on the
tensile side and propagates toward the compressed side. When the crack
enters the compressed tissue, it again tends to travel along the 45°
planes of maximum shear, causing splitting, butterfly chips, or other
types of comminution.

Bones loaded in torsion tend to break in tension and
longitudinal shear because the transverse shear stress created by the
twisting is across rather than along the fibers. The tensile stresses,
however, lie at a 45° angle to the fibers and have only to separate
them rather than to break through them to cause failure. Torsion
typically produces a break that spirals around the bone at this angle
and returns to its starting point along a longitudinal shear stress
plane.

The greater the energy, the more likely the bone is to
break into many pieces. The energy is propagated through the bone as a
stress wave (similar to a sound wave or an earthquake), and the greater
its magnitude, the more likely it is that many parts of the bone will
reach a failure criterion virtually simultaneously. The velocity of a
stress wave in bone is about 3,000 m/sec. The energy required to break
a bone is small compared with that encountered in daily activities.

For example, it takes only about 15 joules (J) of energy
to break the shaft of an adult tibia or femur. The energy released when
a 70 kg person falls to the ground from a standing position is about
500 J. The ability to absorb this energy using eccentric muscle
contractions and deformations of soft tissues usually prevents
fractures from occurring in insignificant falls. If this ability is
impaired by surprise, restrictions, or incapacity, fracture occurs
easily. The propensity of elderly people to fracture their bones easily
reflects the weakness of their bones and the weakness of the muscles
and ligaments that fail to adequately absorb the applied energy, which
instead is transmitted to the bones.

Soft-tissue deformation absorbs energy during an
accident in two ways. First, loads applied perpendicular to the tissues
compress them and propagate stress waves up and down the body. The
tissues effective in this way are skin, fat, and muscle (and fur on
animals or clothing on humans). Second, tissues such as fascia,
tendons, ligaments, joint capsules, and contracted muscle brace bones
against bending by supporting part of the tensile stresses. They absorb
energy as they are stretched, but they must be nearly as stiff as the
bone to be effective. One implication of these mechanisms of energy
dissipation is that in very high energy (high-power) fractures, damage
to the soft tissues tends to parallel the degree of damage to the bone;
thus, the most severe fractures tend also to have severe impairment of
the associated soft tissues on which fracture healing depends.

In 1975, Cruess and Dumont proposed that fracture
healing may be considered to consist of three overlapping phases: an
inflammatory phase, a reparative phase, and a remodeling phase (21).
This scheme, based largely on descriptive histology, has been widely
reiterated. Others have divided fracture healing into four or five
phases (30,53,99).
These divisions are somewhat arbitrary and reflect differences in
emphasis more than in content. Common to all is the concept that the
fracture initiates a biologic cascade, a sequence of steps activated by
and depending on the previous steps. For convenience, we describe
fracture healing in terms of the three phases recognized by Cruess and
Dumont, noting that the reparative phase combines several processes.

The inflammatory reaction immobilizes the fracture: Pain
causes the patient to protect the injured part, and swelling
hydrostatically splints the fracture. At the tissue level, the
inflammatory phase is identical to the typical inflammatory response of
most tissues to traumatic injury. Vasodilation and hyperemia,
presumably mediated by histamines, prostaglandins, and various
cytokines, accompany invasion of the injury site by neutrophils,
basophils, and phagocytes that participate in clearing away necrotic
debris. The fracture hematoma becomes organized as a developing fibrin
network that provides pathways for cell migration. It is also presumed
that during the inflammatory phase, various noncollagenous protein
growth factors that regulate cell migration and differentiation and
that normally are trapped in the bone matrix are released into
solution, where they become active (25,59). The inflammatory phase peaks within 48 hours and is quite diminished by 1 week after fracture.

The reparative phase becomes activated within the first
few days after fracture and persists for several months. Its chief
feature is the development of a reparative callus tissue in and about
the fracture site that gradually is transformed to bone. The callus may
consist of cartilage, fibrous tissue, osteoid, woven bone, and vessels.

The primary callus response is the direct response of
bone to local inflammation, whether the inflammation is caused by
fracture, infection, a foreign body, or a neoplastic process (44,53). Two salient features of the primary

callus response deserve mention. The first is that the response appears
to be relatively independent of mechanical factors, as evidenced from
the significant primary callus response to a foreign body or at the end
of an amputation stump (i.e., half-fracture), or the cap of callus that
may appear at the protruding end of a hollow intramedullary rod (44,53).
Second, the primary callus response does not continue indefinitely. If
the primary callus (i.e., the provisional callus) has failed to unite
two sides of a fracture within a few weeks, it may cease to grow and be
resorbed, as may be observed of the callus at the amputation stump or
on one side of a large segmental defect.

If the primary callus is successful in connecting the
fracture ends, healing progresses to the stage of bridging callus or
hard callus. Although bridging callus seems to imply the directed
growth of tissue outward from the viable regions distal and proximal to
the fracture, the hard callus seems to differentiate simultaneously
throughout its distribution, rather than growing as an advancing front.
Calcification of the callus may be by direct bone formation by
osteoblasts or by endochondral ossification, depending on the local
oxygen tension (4). Typically, growth of a
large callus greatly outpaces the ingrowing vessels, and endochondral
ossification predominates. In a small, mechanically stable defect, such
as a drill hole, primary (intramembranous) woven bone formation
predominates.

The cellular components of the callus derive chiefly
from the marrow and the periosteum. The number of osteoblasts and
osteocytes present at the time of fracture is insufficient to sustain
the high anabolic demands of the growing callus (30).
The differentiation of pluripotential mesenchymal cells, fibroblasts,
and chondroblasts is the primary source of callus cells. (Induction
refers to the differentiation of mesenchymal cells into chondroblasts
or osteoblasts in tissues that do not normally form bone, as observed
in various animal experiments. Induction in this sense is not directly
applicable to fracture healing.)

As the callus calcifies and becomes rigid, the fracture
becomes internally immobilized, and the examiner may consider the
fracture to be healed. The initial calcification is remodeled by
osteoclasts and osteoblasts, leading to the replacement of calcified
cartilage and woven bone by lamellar bone in the final (remodeling)
phase of fracture healing. This phase represents the normal remodeling
activity of bone, although it may remain accelerated in the region of
the fracture for several years, replacing each volume several times
over. In children, the remodeling phase proceeds more vigorously and
includes modeling (independent resorption and formation) and remodeling
(formation coupled to resorption). The result of the remodeling phase
is a gradual modification of the fracture region under the influence of
mechanical loads until it reaches some threshold of optimal shape,
which typically is similar to the shape it had before fracture.

In the presence of perfect apposition of the fracture
fragments and rigid fixation, as may be achieved for instance by
compression plating an osteotomy, the callus response may be suppressed
altogether. In this case, healing proceeds by normal osteonal bone
remodeling. As an increasing number of osteons cross the fracture site,
the two sides become united. Although primary bone healing has been
considered by some to be a goal of fracture repair, it offers no
particular advantage over normal, callus-mediated (i.e., secondary)
bone repair (75,86). It
proceeds very slowly, especially in adults, and the intermediate stages
are weak. A second potential disadvantage of primary bone healing is
that, unlike callus-mediated healing, it does not progress in an
anaerobic environment.

In general, the strength or stiffness of any structure
depends on the product of a geometric factor and the strength or
stiffness of the material within. If the geometric factor is made
larger, the structure can be made of a weaker material and be just as
strong (Fig. 10.1). A callus composed of
material that is relatively weak, for example, can nonetheless achieve
the strength of the intact bone if its diameter is greater.

This principle governs the “engineering philosophy” of
fracture healing: The strength and stiffness required for functional
union are achieved rapidly by formation of a callus that has poor
material but has a high section modulus (large diameter). Woven bone
and calcified cartilage, although weaker than lamellar bone, can be
produced two to five times faster. By locating much of this material
farther from the center of the bone than the original cortex, nature
compensates for the mechanical inferiority of the callus materials.

Figure 10.2 illustrates this
principle, using dimensions typical of a large bone fracture callus.
The external callus itself may easily achieve twice the section modulus
of the intact cortex, and the total callus may have triple this value.
The callus material needs to be only one third to one half as strong as
cortical bone for the callus to return the bone to normal strength. By
the same token, the strength of an abundant, mineralized callus can
substantially exceed that of the original and adjacent cortex.

Clinical intervention to stabilize the mechanical
environment is one of the principles of fracture management. We now
recognize that absolute rigidity should not be the goal of mechanical
intervention, because it entails two potential disadvantages: Stress
protection by fixation devices may cause bone resorption, and lack of
motion at the fracture site inhibits callus formation (72).
Fracture healing seems to benefit from a certain amount of controlled
axial loading and micromotion, although how much is “just right” is
unknown (34,45,54).
Ribs heal with quite a bit of motion; a tibia probably tolerates much
less. The use of less rigid materials (e.g., titanium rather than
stainless steel) and the intramedullary rather than cortical placement
of fixation devices (which decreases the sectional modulus) tend to
increase the amount of micromotion at the fracture site (101).
In a study of fractured dog femurs, Uhthoff et al. found that cortical
bone loss due to stress protection beneath titanium plates was about
one third that under stainless-steel plates, which were 50% stiffer
than the titanium plates (97). Terjesen and Apalset found that 70% to 95% reductions in plate stiffness resulted in a 16% to 100% increase in callus size (92).

As a fracture heals, loads ideally should be borne
increasingly by the bone and less by fixation devices. This gradual
shift can be achieved by using unlocked intramedullary devices or by
dynamizing locked nails or external fixators. Resorbable implants that
are now on the market also have great potential for effecting a gradual
transition of load bearing from the device to bone, provided that their
resorption kinetics can be adequately regulated. Plates and screws are
much less amenable to a gradual shift of load bearing to the bone.

When bone is mechanically loaded, so-called stress-generated potentials are produced by at least two mechanisms (1,35).
Streaming potentials are produced when interstitial fluids are forced
through the calcified matrix by dilatation of some regions and
compression of others. Piezoelectric potentials are produced by
deformation of the collagen molecules. Both electrical potentials are
transient when produced by physiologic loads, because streaming occurs
only while deformation is in progress, and piezoelectric potentials
produced by a prolonged load are canceled by migration of opposite
charges in the interstitial fluids. A permanent electrical polarization
is associated with collagen in bones, however, and this permanent
polarization appears to be altered when fracture occurs (2). The fracture site becomes negatively charged (7). It has been postulated that this polarization is related to the cascade of biological events that result in repair.

This idea has its origins in the observation that cells in amphibian serum are morphologically altered when exposed

to an electrical field (7,9).
Because osteoblast stem cells may include circulating mesenchymal
cells, investigators thought that stress-generated potentials might be
responsible for the differentiation of osteoblasts and play a role in
fracture healing and Wolff’s law (i.e., a bone develops the structure
most suited to resist the forces acting on it). Laboratory
investigations show that bone formation is promoted in the neighborhood
of a cathode, that fresh fractures in animals gain strength more
quickly when electrically stimulated, that disuse osteopenia is
inhibited by electrical treatment, and that bone and cartilage cells in
culture exhibit increased DNA synthesis and other changes when
electrically stimulated (28,29,38,43,47,52,65,66,82).
These findings suggest that the functions of skeletal cells may be
selectively altered by electrical signals arising from normal loading,
fracture, or clinical intervention. This hypothesis has been tested in
numerous clinical trials involving various types of fracture nonunions.

The experiments have usually employed one of two methods
for introducing alternating electrical currents in the bone. Brighton
et al. implanted a cathode directly into the fracture site and passed
about 20 µA of electricity to a supercutaneous anode (12).
Bassett et al. passed electricity through a pair of wire coils disposed
on either side of the fractured limb to induce an alternating magnetic
field in the region of the fractured bone (5).
Magnetic fields penetrate tissues much more readily than electrical
fields, and the amount of current required is low enough to allow
battery power. The alternating magnetic field induces similarly varying
electrical fields and currents in the tissues at the fracture site.

Using these and similar methods, investigators have
generally claimed that treatment of fracture nonunions has been
substantially more dependable than more conventional methods (i.e.,
grafting). These claims have been disputed by critics who assert that
the studies have not been adequately controlled. For various reasons,
it has been difficult to do well-controlled human studies, but the
laboratory work strongly supports the theory that electrical currents
or fields modulate cell function in the skeleton. See Table 10.1 for a summary of factors influencing fracture healing.

Fracture healing is a continuing process that may
progress for several years. Although the criterion is somewhat
arbitrary, a fracture is usually considered healed when the bone can
tolerate the loads normally experienced in everyday activities.
Traditionally, healing has been determined by evidence of bridging
callus on radiographs and by stiffness across the fracture site during
clinical manipulation. These traditional measures of healing are
sufficient for the purposes of fracture management; for some
experimental studies or for careful evaluation of devices or
techniques, however, a more precise determination of the progress of
fracture healing is useful. Three general methods are currently
available.

The motion of the bone across the fracture site in
response to a known load can be measured; this is a refinement of the
clinician’s subjective feel of stiffness when she manipulates the
fracture. Typically, a strain gauge attached to an external fixator is
used to measure the deflection of a tibia in response to known applied
loads (17,22). An example of fracture healing measured in this way is shown in Figure 10.3.

A second technique for measuring fracture healing is to
cause the fractured bone to vibrate by tapping it with a hammer or
vibrating it with a shaker, and then measuring the resonant frequency
of the bone as a whole or the attenuation of the impulse as it crosses
the fracture site (19,71). Healing is assessed by comparison to the intact, contralateral bone.

The third method of measuring fracture healing depends
on measuring the velocity of an ultrasonic wave (from an ultrasound
unit) across the fracture site (33). As the
fracture heals, wave velocity increases. As with the vibrational tests,
healing is measured by comparison with the contralateral uninjured bone.

Although progress in treating fractures in the last 50
years has focused on perfecting the management of the mechanical
environment, it seems likely that future progress will emphasize the
biologic side of fracture healing. Currently, two avenues of biologic
intervention are being developed. Stimulation of osteogenesis involves
enhancement of the migration, division, differentiation, or metabolism
of cells that normally carry out fracture repair. A clinical example is
delayed primary fixation, in which surgical intervention a week or so
after the fracture may reactivate or amplify the cascade of fracture
healing (30,100).
Electrical stimulation also is presumed to enhance osteogenesis, as is
the therapeutic use of protein growth factors. Support of
osteoconduction involves the provision of a substrate or scaffold along
which osteogenic cells can migrate and on which angiogenesis and
osteogenesis can occur. Provision of osteoconductive material is
particularly important in repair of a segmental defect. Collagen is the
natural osteoconductive material, although other proteins and ceramics
are being used experimentally and clinically as osteoconductors. The
combination of an osteoconductive material with a stimulant of
osteogenesis promises to provide a very effective synthetic bone graft.

Although current clinical applications of biologic
agents are still fairly primitive, this area holds great promise for
further improvements in the regulation of fracture healing. Clinical
application of biologic agents would fulfill a prophetic remark made by
Dr. Girdlestone 70 years ago, when he foresaw the future of
orthopaedics shifting from “carpentry to gardening.”

In this century, especially since the 1970s, there has
been a remarkable change in the treatment of fractures and
dislocations. When I began my orthopaedic surgery resident training in
1963, the standard of care for fractures of the shaft of the femur was
skeletal traction, which required an average of 3 months of
hospitalization. The standard today is closed, locked intramedullary
nailing with an average hospital stay of 4–7 days.

The reasons for this tremendous change have been
advances in anesthesia, improvements in sterile technique, and advances
in the technology of internal fixation. We can now operate on patients
who were previously not candidates for surgery, perform surgery with a
minimal risk of infection, and internally fix on a reliable basis
fractures that were previously not fixable. Operative treatment now
dominates the treatment of musculoskeletal trauma to such an extent
that residents today have far less training in the principles of closed
management.

The predominance of operative methods in fracture
treatment is driven by our outcome-oriented society. Patients expect
not only that fractures will heal, but that they will heal in anatomic
position with restoration of normal function. Often these expectations
are unrealistic in view of the severe injuries that occur in our
high-velocity society. Many injuries are now occurring in the context
of the multiply injured patient, where the need for early mobilization
makes nonoperative techniques impractical. For example, in the
Orthopaedic Trauma Service at the University of California, Davis
Medical Center, the average number of fractures per patient is 3.5.
Surgical techniques offer the ability to restore anatomy close to
normal. The rigid fixation obtained often allows early mobilization and
rehabilitation, which optimizes the outcome.

Despite the many advantages of operative care,
nonoperative care remains the foundation on which treatment of
musculoskeletal trauma is based. There are many indications for
nonoperative care, and modern orthopaedic surgeons must be as skilled
in nonoperative as they are in operative techniques. A sound knowledge
of nonoperative techniques also makes the use of operative techniques
more effective and safer. Closed treatment requires as much
thoughtfulness, technical expertise, and attention to detail as does
surgery.

Although this textbook covers primarily operative
orthopaedics, I feel it is essential to provide information on
nonoperative care, and this information is scattered throughout the
chapters in these volumes. This section of this chapter on closed
treatment of fractures and dislocations lays the groundwork for the
other chapters in this section of the text on treatment of fractures.
Although modern textbooks on fracture care, such as those by Rockwood (80,81) and Browner (14)
and their colleagues, cover these techniques in detail, the interested
reader will find it very enjoyable and educational to go back to two
classic works on fracture care, Watson-Jones’s Fractures and Joint Injuries (98) and Charnley’s The Closed Treatment of Common Fractures (18). A monograph by Bleck et al. (10) on plaster cast techniques and a manual by Freuler et al. (27) provide good detail on nonoperative management techniques using plaster and splints.

In nature, the vast majority of fractures heal in the
presence of motion, although deformity is common. Union occurs because
the vascular supply to the bone and surrounding soft tissues is usually
good, and the physiologic stimulus of continued use of the limb
enhances callus formation

and
strengthens the callus formed. In the initial healing process, an
ensheathing callus is formed that begins to immobilize the fracture
fragments. Early during fracture healing, motion can still occur at the
fracture, but translation of the fracture fragments and shortening is
usually impossible after the initial ensheathing callus has formed.

Charnley (18) draws an analogy to a fist gripping a stick (Fig. 10.4).
Most bone in fracture callus comes from endosteal tissues, which
quickly fills in the ensheathing callus. As it becomes progressively
thicker, total immobilization of the fractured bone ends occurs. This
method of healing has the mechanical advantage of producing a callus
that is much larger in diameter than the fractured bone. It takes
advantage of the increased polar moment of inertia created by the thick
callus. After complete consolidation, in fact, this thickened area of
bone is often stronger than the unaffected shaft (Fig. 10.5).
The bone ends themselves are usually somewhat avascular because of the
injury and do not directly participate in this early phase of healing.

Once completely immobilized within the callus, the bone
ends are slowly revascularized and remodeled. The large peripheral
callus is slowly resorbed and the shape of the bone returns toward
normal after several years of remodeling. This type of union is
virtually 100% successful in nature in ribs, clavicles, and membranous
bones. In the mid diaphysis of such bones as the tibia, the limitations
of blood supply and excessive motion produced by attempted use of the
limb commonly lead to nonunion.

The purpose of nonoperative treatment methods, then, is
to hold the broken bone in a position as close to its anatomic position
as possible to prevent malunion, to reduce excessive motion in order to
prevent nonunion, and to allow earlier function than would otherwise be
possible. In addition, the immobilization substantially reduces pain.

By contrast, surgery, which involves soft-tissue
dissection and direct mechanical trauma to bone, reduces the blood
supply to bone and the surrounding soft tissues. Except for closed
intramedullary nailing, bone union usually takes longer if operative
methods are used. Because of the prolonged period necessary for
revascularization, rigid fixation over long periods of time is usually
required. With rigid fixation, bone union occurs by direct osteonal
modeling and callus formation is suppressed; this results in slower and
mechanically less strong union. The combined risks of
devascularization, slower and weaker bone union, and operative
complications must be offset by the advantages to be gained by
operative treatment.

Although skin-tight plasters were popular at one time,
they are no longer used because they present the danger of pressure
sores and compartment syndrome. Freuler et al. have shown that the
additional immobilization provided by using unpadded plaster is not
worth the many risks (27).

Tubular stockinet of cotton, synthetics, or a
combination is available in widths from 2 to 12 inches and serves as a
useful liner under most casts (Fig. 10.13).
When treating fresh fractures, I prefer not to line the entire cast
with stockinet because, if swelling occurs, the stockinet can be quite
difficult to cut. Place the tubular stockinet only at the ends of the
cast for trimming (Fig. 10.14). When applying stockinet around joints, avoid wrinkles by cutting the stockinet on the concave surface and overlapping it (Fig. 10.15 and Fig. 10.16).
Tubular stockinet can be cut on the bias to produce a bandage material
that is stretchable and conforms well to the extremity but is not
elastic. It is very useful for overwrapping splints and soft dressings (Fig. 10.17).
Heavier specialized knitted stockings are used for cast-braces where
more uniform compression of the limb is desirable, and thicker material
is necessary to protect the limb from the plaster, as the limb will be
used much more actively in a cast-brace.

For padding, most surgeons now use a sheet cotton commonly known as Webril that comes in rolls 2, 3, 4, and 6 inches wide (Fig. 10.18).
This sheet cotton is fairly noncompressible and, if used thick enough
over bony prominences, can serve as the only padding material in the
cast.

Felt is useful for providing extra padding and is available

as black felt or a more dense white felt, available up to ½-inch thick.
It can be stripped in half to produce thinner sheets as necessary. Also
useful is synthetic foam padding with adhesive backing, which can be
adhered to the limb over particularly sensitive or prominent areas. The
disadvantage of synthetic foam is that it is more compressible and less
likely to be effective.

Circumferential casts of differing materials have been
used since first developed by the ancient Egyptians. The first plaster
bandages were used by Andonius Mathijsen, a Flemish army surgeon, in
1852. The plaster of Paris used in plaster bandages is derived from
gypsum. Plaster of Paris is made by pulverizing and heating gypsum to
dehydrate it; the result is anhydrous calcium sulfate. When water is
added, it crystallizes back into gypsum in an exothermic reaction. This
exothermic reaction produces enough heat that if a cast is overly thick
and laid on an impervious surface such as a plastic-covered pillow,
second-degree burns can occur. Commercial plaster bandages are made by
coating gauze with the plaster of Paris, using starch as an adhesive.

Various chemicals are added to create different setting
times and handling characteristics. Most plaster is available in either
a standard or fast-setting variety. Extra-fast-setting plaster, which
sets in 2–4 min, is useful in clubfoot casts on small children.
Standard or fast-setting plaster requires 5–8 min. Setting times are
affected by ambient

temperature,
humidity, thoroughness of wetting, and water temperature. Long crystal
lengths make a stronger cast, and the ideal water temperature is about
22°C (72°F). The plaster should generally be soaked for about 4 min.

Commercial bandages are available in rolls 2, 3, 4, 5, 6, and 8 inches wide and in varying sizes of splints (Fig. 10.19 and Fig. 10.20).
Splints are available in 3 × 15, 4 × 15, 5 × 30, and 5 × 45 inches.
Luck describes the parameters affecting plaster strength and use (48).

Plaster rolls with elastic fibers in them are also
available. The weave of the gauze and elastic fibers allows the cast to
be applied more tightly and with more uniform molding over irregular
surfaces. It is useful as the initial layer in cast-braces. It is very
easy to apply elastic cast materials too tightly; use them with caution.

Plaster of Paris with incorporated resins that make the
plaster stronger and more water-resistant is also available, but for
the most part it has been replaced by entirely synthetic or fiberglass
cast materials. These materials are lightweight and strong and can be
applied in much thinner constructs than plaster of Paris. They are not
weakened by immersion in water. They are available in many colors and
are very popular with patients. The disadvantages of the synthetic
materials are that they are far more expensive, much more difficult to
apply, and not as versatile as plaster of Paris. In addition, it is
very difficult to mold fractures through synthetic materials, and they
are generally not used in the initial treatment of unstable fractures.
Because of the rigidity of the fiberglass, they cannot be spread. They
can, however, be quite useful as an overwrap of one or two layers on
regular plaster of Paris casts to increase their strength and protect
the outer surface. Allergy is also more common with the synthetic cast
materials; in plaster of Paris, it is nearly unheard of.

Other materials useful in the cast room are gauze rolls,
tape, muslin bandage, elastic (Ace) bandages, and various dressing
materials. A plentiful supply of good-quality disposable rubber gloves
is essential, as plaster should always be handled with gloved hands to
prevent the rough texture of your skin from dragging the plaster out of
the gauze as it is rubbed, producing a rougher and less desirable cast
finish. Cornstarch and baby powder are useful for dusting

the
skin, particularly where skin contact, such as in the axilla, may
result in irritation. Do not use talcum powder, as it is too rough.

Small blocks of wood or commercially available plastic
cast wedges are useful for cast wedging and holding split casts open.
Long wood sticks or rolled newspapers are useful for making reinforcing
bars for shoulder and hip spica casts. An indelible pencil for writing
the diagnosis, drawing the fracture, or entering other useful
information on the cast is handy (Fig. 10.21).

Equipment essential to a well-furnished cast room
includes hooks in the ceiling for suspension, broad stainless-steel or
synthetic work surfaces on which to spread plaster, mechanical or
hydraulic tables that can be elevated for plaster application, special
orthopaedic tables for the application of spica casts, bandage
scissors, disposable #10 and #20 blades, an electric cast saw with an
attached vacuum (Fig. 10.21), and special tools for cutting, bending, and splitting casts (Fig. 10.22).
Various types of foam-rubber bolsters and stands or devices for
supporting the limb during plaster application are available and are
quite useful, particularly when the surgeon must work unassisted.

The application of a standard below-knee cast will be used to demonstrate the general principles of plaster cast application.

Well-applied plaster splints can be used for nearly all
the smaller tasks performed by casts, except for the spica casts. The
primary advantages of splints are that they are lighter in weight than
casts, allow for swelling of the limb, and are removable. They are,
however, much weaker, and the fact that they are removable may pose a
problem in noncompliant patients.

The strongest and best-conforming splints are made by
first applying a full cast. After drying, bivalve the cast and trim the
edges.

Continuous traction is indicated in the treatment of
fractures when reduction of the fracture or proper length of the limb
cannot be maintained by the static immobilization provided by casts and
splints. It is necessary in the presence of deforming forces caused by
soft-tissue tension in the muscles, tendons, and ligaments, and by
hydraulic forces generated by bleeding into and swelling in the
soft-tissue envelope surrounding the fracture. Traction may also be
necessary to treat unstable dislocations, particularly of the hip,
where static methods are inadequate or impractical. Because of the
sophistication of modern methods of internal and external fixation, it
is uncommon to treat fractures or dislocations definitively in
traction. Disadvantages include the need for prolonged bed rest and

prolonged
and expensive hospitalization. Additionally, the return to function is
slow; the patient is recumbent in traction for so long that muscle
atrophy, joint stiffness, and general cardiovascular deconditioning
result.

Traction is almost never used for upper extremity
problems, as current methods of internal and external fixation are
usually superior. At the University of California, Davis, Medical
Center, a busy level 1 trauma center with more than 3,000 trauma
admissions per year, I have not used traction since the 1980s for even
the temporary treatment of a disorder in the upper extremities, but
olecranon pin traction is described below because it is a very useful
method that I used frequently in the 1960s and early 1970s.

Musculoskeletal surgeons should be familiar with the use
of traction, as it is a good backup method for situations where
internal and external fixation are impossible. In particular, it may be
useful in the management of major soft-tissue injuries in the upper
extremity because the overhead suspension provides ready access for
wound care. With the advent of percutaneous pin fixation for
supracondylar fractures of the humerus in children, traction treatment
has virtually disappeared and in most Western countries is not
indicated.

Traction is still commonly used in the lower extremity,
however. Common indications are Malgaigne injuries of the pelvis with
vertical instability, fractures of the hip and shaft of the femur, and
fractures of the tibia and fibula. Unstable posterior dislocations of
the hip are often immobilized in skeletal traction until soft-tissue
healing occurs. Skin traction is commonly used to immobilize elderly
patients with fractures of the hip as an emergency measure before
performing internal fixation. Skeletal traction through either the
distal femur or the proximal tibia is used for the temporary and early
treatment of unstable fractures of the pelvic ring and acetabulum, the
hip in younger patients, and femoral shaft and supracondylar fractures
of the femur. Where traction is used for vertically unstable fractures
of the pelvic ring, fixation is often supplemented by an external
fixator on the pelvic ring.

In the vast majority of the injuries mentioned, internal
or external fixation is the definitive method of treatment; however,
local soft-tissue and systemic conditions may contraindicate surgery
and necessitate prolonged definitive treatment in traction. Since
external fixator and intramedullary nailing have not been tested in the
face of the major mass casualties produced by war, skeletal traction
remains the only proven treatment for high-velocity gunshot wounds of
the femur in a military situation. It is highly likely that external
fixation is a better treatment method, but its efficacy in this
specialized situation has not been proven.