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50
Fig. 3.10 Sagittal and
Axial T2 MRI cuts
demonstrating a central
lumbar disc protrusion
A. J. Khanna and B. Gelfand
joints, and more will enhance a surgeon’s ability
to identify pathologic conditions.
The spine is generally composed of 7 cervical
vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae, the sacrum, and the coccyx. The vertebral
bodies are separated by intervertebral discs,
while the facet joints provide articulations of
adjacent vertebrae. Fibrous joints, including the
ligamentum avum, interspinous ligaments, and
supraspinous ligaments provide anatomic connections spanning the entire spine.
Disc Herniations represent one of the most
common spinal pathologies seen by orthopedic
surgeons. Components of the intervertebral disc
include the annulus pulposus (outer annulus) and
nucleus pulposus (inner annulus). On MRI, discs
show intermediate signal on T1 weighted images
and high signal on T2 images. The nucleus pulposus, when compared to normal vertebral marrow, appears hyperintense on T2 and hypointense
on T1 weighted images. Over time, as patients
age and the disc degenerates, T2 signal decreases
within the nucleus pulposus and the disc appears
dark on all sequences.
When evaluating a sagittal and axial T2 MRI
of the spine, analyzing the posterior aspect of
the intervertebral disc will demonstrate any herniation or sequestration as well as any other
pathology that could be causing nerve root compression (Fig.3.10).
Bone Scan
In contrast to radiographs, CT and MRI which
provide information about the anatomic nature of
the structure in question, nuclear scintigraphy or
bone scan, provides physiologic information.
Bone scan, or more specically three-phase bone
scintigraphy, is a form of nuclear imaging which
demonstrates bone turnover.
The fundamentals of acquiring bone scans are
based on tissue uptake of radiopharmaceutical
agents. When a patient is injected with an agent
that emits gamma rays, such as Technetium-99m
phosphate, the distribution of the rays can be captured by a gamma (scintillation) camera. The
gamma cameras are designed to scan large areas
of the body and can rotate to collect from multiple sites of the body. Technetium-99m is the most
common radioisotope used given that it is inexpensive, has a half-life of approximately 6h and
its photon energy is easily captured by gamma
cameras.
The typical bone scan occurs in a “threephase” manner: Blood ow phase, soft tissue
phase, and delayed/bone phase. Increased uptake
is seen in the blood ow phase in areas of mature
blood vessels, the soft tissue phase shows
increased vascularity in the setting of acute
inammation and bone phase demonstrates sites
of bone turnover.
3 Musculoskeletal Imaging
51
Specic to bone scans, 99m Tc-Methylene
diphosphonate (MDP) is often injected as this
isotope is sensitive for bony abnormalities. The
amount of MDP uptake is based on the osteoblastic activity and vascular nature of bone. Thus,
bone scans help provide physiologic information
of bone relatively diffusely across the body at the
expense of specicity as well as poor spatial and
anatomic resolution.
Clinically, bone scan is most useful for evaluating metastatic disease, malignant tumors, metabolic disease, osteomyelitis, as well as stress
fractures.
With regard to osteomyelitis, bone scan is a useful tool to help aid in diagnosis especially within
the acute form of the infection. Within the rst 24h
of infection, radiotracer uptake is generally
increased at the site of osteomyelitis. Often, conventional radiographs are unable to detect bony
changes early in the infectious course thus proving
the usefulness of bone scan. Building off these
principles, bone scan is also useful to help differentiate osteomyelitis from another entity like cellulitis or septic arthritis. Increased uptake is seen in all
three phases in osteomyelitis compared to increased
uptake in the blood ow and soft tissue phase in
cellulitis. When compared to MRI, bone scan
offers the advantage in that it is able to detect multiple sites of infection compared to the anatomic
region scanned during a MRI. This is especially
useful in a pediatric patient whose age makes clinical history difcult to obtain while there is a clinical concern for multiple areas of osteomyelitis.
In the setting of metastatic disease, signicant
bony destruction must occur before conventional
radiographs can detect changes thus demonstrating the importance of bone scan in diagnosing
disease in the early stages. Although this is a general principle, orthopedic surgeons must be wary
as multiple myeloma and purely osteolytic
tumors may not produce increased uptake and be
viewed as a false negative.
Compared to metastatic disease, bone scan has
less use in the setting of primary bone tumors.
Although uptake is seen, the area may not be
accurate with regard to margins and the amount of
soft tissue involvement or extension. Additionally,
uptake seen on bone scans cannot distinguish
between malignant and benign lesions. Overall,
bone scan proves more effective in excluding
multifocal disease or metastatic disease opposed
to analyzing primary solitary lesions.
The nonspecic nature of uptake seen on bone
scans can pose a challenge when interpreting
scans in the setting of trauma or persistent pain.
Both bony trauma and degenerative osteoarthritis
will appear as areas of focal increased uptake.
Generally, uptake reaches its peak approximately
7days after a fracture with return to normal up to
1year after the initial injury. Stress fractures will
demonstrate increased focal uptake.
PET Scan
Positron emission tomography (PET) scan is
another modality used to assess the physiologic
activity in tissues with the use of glucose metabolism. In contrast to bone scans, in a PET scan,
patients are injected with 18-F-labeled 2-uoro2-deoxyglucose, which is a marker of glucose
metabolism when emitted.
Clinically, PET Scans are most often used in
the setting of evaluation of metastatic disease as
well as tumor recurrence. Studies have demonstrated increased sensitivity and specicity for
differentiating malignant and benign lesions.
In the arthroplasty setting, PET scans have
become useful in determining if a patient’s pain
surrounding an implant is secondary to aseptic
loosening as opposed to an indolent infection.
It can be difcult to diagnose a chronic prosthetic joint infection if laboratory data is equivocal, thus proving another role for the use of
PET scan.
Overall, PET scan is an important diagnostic
tool when rst line imaging does not yield enough
information and a test all orthopedic surgeons
should be familiar with.
Further Reading
Domb BG, Tyler W, Ellis S, McCarthy E.Radiographic
evaluation of pathological bone lesions: current spec-
trum of disease and approach to diagnosis. J Bone
Joint Surg Am. 2004;86-A(Suppl 2):84–90.
52
A. J. Khanna and B. Gelfand
Grissom L, Harcke HT, Thacker M.Imaging in the surgi-
cal management of developmental dislocation of the
hip. Clin Orthop Relat Res. 2008;466(4):791–801.
Sanders TG, Miller MD.A systematic approach to mag-
netic resonance imaging interpretation of sports
medicine injuries of the knee. Am J Sports Med.
2005;33(1):131–48.
Sanders TG, Morrison WB, Miller MD. Imaging tech-
niques for the evaluation of glenohumeral instability.
Am J Sports Med. 2000;28(3):414–34.
Shindle MK, Foo LF, Kelly BT, etal. Magnetic resonance
imaging of cartilage in the athlete: current techniques
and spectrum of disease. J Bone Joint Surg Am.
2006;88(Suppl 4):27–46.
Court-Brown CM, Tornetta P, McQueen MM, Ricci WM,
editors. Rockwood and Green’s fractures in adults. 9th
ed. Wolters Kluwer Health; 2019.
Fayad LM, Bluemke DA, Fishman EK.Musculoskeletal
imaging with computed tomography and magnetic
resonance imaging: when is computed tomography the study of choice? Curr Probl Diagn Radiol.
2005;34:220–37.
Genant HK, Wilson JS, Bovill EG, Brunelle FO, Murray
WR, Rodrigo JJ. Computed tomography of the
musculoskeletal system. J Bone Joint Surg Am.
1980;62:1088–101.
Lee E, Worsley DF. Role of radionuclide imaging in
the orthopedic patient. Orthop Clin North Am.
2006;37:485–501.
Abdel-Dayem HM.The role of nuclear medicine in pri-
mary bone and soft tissue tumors. Semin Nucl Med.
1997;27:355–63.
Alazraki NP. Radionuclide imaging in the evaluation of
infections and inammatory disease. Radiol Clin
North Am. 1993;31:783–94.
Santiago Restrepo C, Giménez CR, McCarthy K.Imaging
of osteomyelitis and musculoskeletal soft tissue infec-
tions: current concepts. Rheum Dis Clin N Am.
2003;29:89–109.
Delank KS, Schmidt M, Michael JWP, Dietlein M,
Schicha H, Eysel P. The implications of 18F-FDG
PET for the diagnosis of endoprosthetic loosening and
infection in hip and knee arthroplasty: results from
a prospective, blinded study. BMC Musculoskelet
Disord. 2006;7:20–8.
Wilson JS, Korobkin M, Genant HK, Bovill EG Jr.
Computed tomography musculoskeletal disorders.
AJR Am J Roentgenol. 1978;131:55–61.
Morgan S, Saifuddin A.MRI of the lumbar intervertebral
disc. Clin Radiol. 1999;54(11):703–72.
Skeletal Trauma
JohnL.Johnson andRobertGolden
4
Introduction
A foundation in orthopedic trauma and fracture
care is crucial to understanding the treatment of
the musculoskeletal system. Skeletal trauma can
be divided into fractures, dislocations, and combinations of these, i.e., fracture/dislocations. A
fracture is a disruption in the continuity of cortical and/or cancellous bone. A dislocation is a disruption of the normal articulating anatomy of a
joint. Dislocations can be either a complete disruption of the normal anatomy or a partial dislocation, termed as subluxation. A fracture/
dislocation is a fracture occurring in or near a
joint that results in a subluxation or dislocation of
the joint.
J. L. Johnson (*)
MedStar Georgetown Orthopedic Institute,
Georgetown University School of Medicine,
Washington, DC, USA
Department of Orthopedics, MedStar Georgetown
University Hospital, Washington, DC, USA
e-mail: John.L.Johnson@medstar.net
R. Golden
MedStar Georgetown Orthopedic Institute,
Georgetown University School of Medicine,
Washington, DC, USA
Department of Orthopedics, MedStar Washington
Hospital Center, Washington, DC, USA
e-mail: Robert.D.Golden@medstar.net
Fractures
Initial Evaluation
Initial evaluation of a trauma patient with an
extremity injury should begin with a thorough
history, physical examination, and radiographic
evaluation. Advanced Trauma Life Support
(ATLS) principles should be applied prioritizing
life over limb.
The history should include the mechanism
and timing of injury. The mechanism can yield
important information for treatment of the injury
in understanding the fracture pattern, risk of
associated injuries, and the degree of soft tissue
and neurovascular involvement. Important components of the mechanism are blunt vs. penetrating and high vs. low energy. There is a direct
correlation between the amount of energy
absorbed by the extremity and resulting bone and
soft tissue damage. A high energy mechanism
such as a motor vehicle collision, or fall from signicant height carries more signicant risk of
injuries to other musculoskeletal structures, head
injury, or chest/abdominal injury. Lower energy
mechanisms such as a ground level fall are more
likely to be isolated injuries with a lower risk of
multisystem trauma, and extensive soft tissue
damage. However, patients with a pre-existing
poor soft tissue envelope such as the elderly may
have a signicant soft tissue injury despite a relatively low energy mechanism injury. The timing
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2024
W. F. Postma et al. (eds.), Essentials of Orthopedic Surgery,
https://doi.org/10.1007/978-3-031-66215-7_4
53
54
J. L. Johnson and R. Golden
of the injury must also be noted. This is particularly important in the case of a vascular injury
and determining the length of time a limb has
been ischemic. Ischemia leads to increased risk
of infection and tissue loss after 4–6h of warm
ischemia time.
Physical examination of a trauma patient
should include the inspection and evaluation of
the entire patient to identify any occult injuries as
well as a thorough inspection of the affected limb
noting any gross deformity and a circumferential
examination of the skin. Any open wounds,
abrasions, or bruising should be noted. The neurovascular status of the limb should be carefully
ascertained and documented. The pulses distal to
the injury should be attempted to be palpated. If
there is no pulse, this may be due to vascular
injury, occlusion due to a displaced fracture or
dislocation, vascular spasm, or poor perfusion
secondary to shock. A Doppler ultrasound may
be used to nd the pulse and ABIs (ankle brachial
index) documented to better dene the vascular
status of the limb. Radiographic evaluation
should include at a minimum two orthogonal
views of any affected bone or joint or any area
with any suspicion of an injury, as well as the
joint above and below any area of concern.
With a complete history, physical examination, and radiographic evaluation of the affected
extremity, the principles described in the remainder of this chapter may be applied to develop a
plan for appropriate treatment.
Fracture Descriptors
An adequate grasp of describing fracture patterns
is useful both for communication with members
of the care team and for appropriate treatment.
Though each fracture is different, most of them
can be sorted into the following categories. These
general descriptors are as follows:
Open versus closed: A closed fracture is one in
which the skin is intact over the fracture site.
An open fracture is a fracture with a disruption
of the skin within the zone of injury of the frac-
ture. Open fractures were colloquially known
as “compound fractures.” While this term may
be useful in discussions with patients, it is not
used in orthopedic terminology.
It is important to understand that the clinical and
radiographic appearance of a fractured extremity is a snapshot in time. Bones can shift great
distances while being fractured; shortening,
angulating, and translating. Wounds that
appear remote from the resting position of the
fracture at the time of patient presentation may
in fact have been caused by the bone during the
process of it being fractured.
Simple versus comminuted: A simple fracture is
one in which there are only two major fragments and one fracture line. A comminuted
fracture is one in which there are multiple
fragments of bone and multiple fracture lines.
Complete versus incomplete: A complete fracture
is one in which the fracture line goes completely
across the bone. Incomplete fractures, almost
exclusively seen in children, have a fracture line
that only crosses one cortex of the bone involved.
Fracture Deformities
A fracture can be deformed in any one of three
possible planes. Traditionally, the deformity is
described by the relative position of the distal
fragment in relation to the proximal fragment.
Classic deformations are described as follows:
1. Displacement is the amount of translation of
the distal fragment in relation to the proximal
fragment in either the anterior/posterior or the
medial/lateral planes. Displacement is the
opposite of apposition.
2. Angulation occurs when two fracture fragments are not aligned and an angular deformity is present in either the anterior/posterior,
the medial/lateral planes, or a combination of
both planes. Alignment means that the axes of
the proximal and distal fragments are parallel
to each other and the joint above and below
are in the normal (anatomic) relationship.
Angulation is typically described by the direction in which the apex of the angle points—
medial, lateral, anterior, posterior, etc.
4 Skeletal Trauma
55
3. Rotation occurs when there is an axial change
between the two fractured fragments in the
transverse plane.
4. Shortening or lengthening occurs when the
distal fragment is positioned in relation to the
proximal fragment to either decrease or
increase the overall length of the fractured
bone.
Fracture Patterns
A number of basic fracture patterns have been
described. They include:
1. Transverse: A pattern where the fracture line
is perpendicular to the shaft of a long bone
(Fig.4.1).
2. Spiral: A pattern secondary to a torsional
mechanism where the fracture line “wraps
around” the bone. This typically results in two
sharp diaphyseal spikes on each end of the
fracture (Fig.4.2).
3. Oblique: A pattern where the fracture line
crosses the bone at an angle (Fig.4.3).
4. Impacted or compressed (Fig.4.4).
5. Avulsion (Fig.4.5).
6. Complex (Fig.4.6).
7. Segmental: A pattern where the bone (often
the diaphysis) is fractured in more than one
location. This pattern is most commonly seen
in high energy mechanisms (Fig.4.7).
Fracture Mode ofLoading
The biomechanics that create a fracture can
offer some information as to the likely mechanism of injury and clues to other injuries that
might have occurred in association with the primary and often more obvious injury. Biomechanical analyses have demonstrated the typical
fracture patterns that occur with specic modes
of loading:
Fig. 4.1 Transverse fracture—a transverse fracture of the
radius in a pediatric patient. The fracture line is perpendicular to the shaft
Fig. 4.2 Spiral fracture—a spiral fracture of the humeral
shaft. The arrows mark the diaphyseal spikes
56
Fig. 4.3 Oblique fracture—an oblique
radial shaft fracture
J. L. Johnson and R. Golden
Fig. 4.4 Impacted fracture—a pilon fracture
with metaphyseal impaction. The compressed
metaphyseal bone is marked by the arrow
4 Skeletal Trauma
Fig. 4.5 Avulsion fracture—this is
a “tongue type” calcaneal fracture.
The yellow area denotes the
avulsion portion due to the insertion
of the achilles
57
Fig. 4.6 Ballistic humeral shaft
fracture—the proximal fragment is
severely comminuted; the distal
component is oblique
58
Fig. 4.7 Segmental fracture—a segmental fracture in the
femoral shaft
– Bending loading produces a transverse frac-
ture
– Torsional loading produces a spiral fracture
– Axial loading produces a compression or
impacted fracture
– Tensile loading produces an avulsion fracture
– Combined loading such as bending and axial
loading, which together produce an oblique
fracture.
Taken together with the magnitude of fracture
displacement and comminution, the fracture pattern
suggests the direction and amount of force applied
during the injury. From the degree of injury, an
extrapolation can be made that predicts the amount
of soft tissue damage associated with the fracture.
J. L. Johnson and R. Golden
The types of injury involving them are covered in
the following sections.
Vascular Injury
Vascular injuries can sometimes be caused by or
associated with fractures. When arterial injuries
occur, it is always an emergent situation. Vascular/
Trauma surgeons should be consulted immediately.
Often a combination case in which the orthopedic
surgeon temporarily stabilizes the bone and the
vascular surgeon restores blood ow is undertaken
emergently in order to preserve the limb. Injury to
arterial vessels is uncommon because these vessels
are elastic and mobile. The vessels can be damaged
when they are either inelastic as in atherosclerosis
or xed by soft tissue structures.
One special form of a vascular injury is compartment syndrome. Increased pressure within a
fascial compartment can cause muscle necrosis in
a relatively short period of time. In the front of the
leg, for example, the anterior compartment is
bounded by the tibia, the syndesmotic membrane,
the bula, and the fascia overlying the tibialis anterior muscle. Since none of these four boundaries
can be stretched, the contents of the compartment—that is, the tibialis anterior muscle among
others—will necrose from excess increased pressure occurring after trauma. Muscle necrosis and
nerve damage can occur in a relatively short period
of time. Early diagnosis is essential. The diagnosis
of a compartment syndrome is primarily based on
clinical ndings although in obtunded patients
compartmental pressure monitoring can assist
with the diagnosis. The earliest and most reliable
diagnostic indicator of compartment syndrome is
pain out of proportion on exam, particularly with
passive stretch of the muscles in the involved compartment. Once the diagnosis is conrmed, immediate surgical release of the compartment via
fasciotomy is required.
Soft Tissues
As mentioned above, a number of soft tissues can
be damaged. They include the periosteum, blood
vessels, nerves, muscles, tendons, and ligaments.
Nerve Damage
A nerve can be compressed, contused, or
stretched due to a fracture or dislocation. Classic
examples include radial nerve injury secondary
4 Skeletal Trauma
to fractures of the distal humerus and sciatic
nerve injury following posterior fracture dislocations of the hip. The types of neural injuries are
as follows:
1. Neuropraxia. Death of the axon does not
occur. The most common mechanism is nerve
stretch and usually improves by itself in
weeks to months. The nerve is anatomically
intact and physiologically nonfunctional.
2. Axonotmesis. Axonotmesis is an anatomic
disruption of the axon in its sheath.
Improvement follows regeneration, the axon
growing at a rate of 1 mm a day along the
existing axonal sheath.
3. Neurotmesis. This is an anatomic disruption
of the nerve including the sheath. Surgical
repair is required if recovery is to occur.
Muscle Injury
In any fracture or dislocation, there is always some
associated muscle damage. The extent of this damage and the effects vary depending on the direction
of force and the amount of energy imparted to the
limb during fracture. Rarely complete transection
of the muscle belly can occur. More often a partial
tear or contusion occurs. Heterotopic ossication
is a specic complication of muscle contusion in
which heterotopic bone forms within the damaged
muscle or in normal muscle after traumatic brain
or spinal cord injuries. Certain fractures, such as
acetabulum fractures requiring a posterior
approach for xation and distal humerus fractures,
are more prone to develop heterotopic ossication
than other fractures (Fig.4.8).
Ligament Tears
59
Fig. 4.8 Heterotopic ossication (HO)—the arrow is
pointing to an area of HO that occurred following xation
of an acetabular fracture
Age is an important determinant of the injury
type that results from the application of a traumatic force. At any given age, the “weak link,” or
the rst structure to fail, varies; it could be bone,
ligament, or cartilage growth plates. Once
growth plates close, ligaments are the most
likely structures to fail in an injury. Ligamentous
strength is relatively constant throughout life.
With aging, there is a decrease in cancellous
bone volume and an increase in cortical bone
porosity. With increasing age, therefore, bone
becomes weaker; hence, ligament and cartilage
injuries are less likely than bone injuries. Thus,
the same mode of loading can produce different
injury patterns depending on the age of the
patient. A lateral force, such as a tackle in football or a blow by an automobile on the outer side
of the knee, may cause a fracture through the
distal femoral growth plate in a 12-year-old, a
tear of the medial and anterior cruciate ligaments
in a college football player, and a tibial plateau
fracture in a 70-year-old.
Ligaments regulate the movements of bones that
form a joint. Damage to these structures are
called sprains. Complete disruption can result in
a joint dislocation in the acute setting and instability of the joint in the long term.
Classic Fractures
A number of classic fracture types have been
described in the literature. They are dened in the
sections below.