Diagnostic Radiology of Musculoskeletal System Zhang Zhaohui Department of Radiology The First Affiliated Hospital of Sun Yat-sen University
Definition: complete or incomplete break in the continuity of bone or cartilage Clinical presentation: traumatic history, local tenderness, swelling, functionally disorder, deformity Radiological appearance: fracture line General introduction of fracture
Complete versus incomplete
Complete fractures involves the entire circumference (tubular bone) or both cortical surfaces (flat bone) of a bone. It can be subdivided into several types, such as transverse, oblique, spiral fracture. In incomplete fracture , the break in the cortex does not extend completely through the bone.
Fracture with more than two fragments are comminution fracture.
Incomplete fracture The break in the cortex does not extend completely through the bone
By convention, long bones are divided into thirds, and lesions are described as being in the proximal, middle, or distal third or at the junction of the proximal and middle or middle and distal third.
If a fracture is located near an articular cortex, it should be described as either intra- or extra-articular.
The term apposition refers to the state of contact of the ends of the fracture fragments. Complete and normal apposition is termed anatomical apposition.
Displacement: If fracture fragments are in partial apposition, the term displacement is used. By convention, the distal fragment is said to be displaced in the designated direction with respect to the proximal fragment.
Fracture at the junction of the proximal and middle third of femora There is later displacement of distal fragment with respect to the proximal fragment.
Bayonet apposition refers to a fracture in which the fragment ends are not in contact with one another but the fragments overlap one another, leaving the shafts of the fragments in contact and causing loss of length of involved bone.
Fracture at the junction of the middle and distal third of tibia and fibula with bayonet apposition There is also anterior and later displacement of distal fragment with respect to the proximal fragment.
Distraction is complete lack of apposition, and most commonly secondary to either excessive traction or interposed tissue. In a non-acute fracture, the appearance of distraction may be due to resorption of the ends of the fragments.
Alignment Alignment refers to the relationship of the long axes of the fracture fragments. Loss of normal alignment is angulation. Direction of angulation may be correctly described in two ways. The least confusing description is the direction of angulation of the apex of the fracture site. Alternatively, angulation of the distal fragment with respect to the proximal one may be described. These two descriptions are exactly reversed in a given fracture. For example, a fracture of the femur pointing anteriorly would be described either as apex anterior angulation or as posterior angular displacement of the distal fragment. Either description is correct as long as it is clearly stated.
Fracture at the middle third of tibia and fibula with apex anterior angulation There is anterior displacement of the distal facture fragment of tibia with respect to the proximal fragment. The aposition of fracture fragments of fibula is normal.
Rotation Rotation of fracture fragments can be evaluated by comparison of the direction of the joints proximal and distal to the fracture. If this is not possible, malrotation can often be inferred from a radiograph if the anteroposterior and lateral diameters of a long bone are different and the fracture fragments do not appear congruent.
Healing of fracture Healing of fracture begins with the immediate hemorrhage in and around it. This is followed by ingrowth of granulation tissue, the formation of an osseous and sometimes cartilaginous matrix, decalcification and resorption of the devitalized bone in the opposing ends of the fragments, progressive calcification of the osseous and cartilaginous matrix (callus formation) and finally, shaping of the shaft at the junction of the fragments.
Formation of a small amount of calli around the fracture of clavicle Factors that have influence on the healing of fracture include age, fracture type, nutrition, treatment, etc. Callus usually cannot be detected earlier than the 3rd week after fracture in older children or adults but becomes visible during the 2nd week in the new born.
Formation of calli around the fracture at distal third of radius
Development of callus: more opaque, more clearly defined, and take a fusiform shape
Bony union of the fracture at proximal humerus Disappearance of fracture line, anatomical apposition, normal alignment, slight irregularity of humerus at the fracture site.
Complications of fractures include: un-union or delayed union; deformity of union; osteoporosis after trauma; infection of bone and joint; necrosis of bone; degeneration of joint; myositis ossificans, etc.
Un-union fracture The opposing ends of fracture fragments become thin with increased density
Deformity of union
Deformity of union with post-traumatic osteoporosis
Un-union of femoral neck fracture with necrosis of femoral head (collapse of femoral head with increased density)
Post fracture myositis ossificans Radiographs show high density ossifications in the soft tissue （）
Greenstick fracture An incomplete fracture in the developing tubular bone caused by bending stress. Greenstick fractures are characterized by angling or buckling of the cortex , and a lucent fracture line often invisible. Common fractures
Radiographs show angling (lateral view) and slight buckling (AP view) of the cortex of distal third of radius without a lucent fracture line. Green stick fracture
Epiphyseal separations Epiphysis and most of the cellular elements of the contiguous growth plate separate from the metaphysis. In an older child, it may create a metaphyseal fragment.
The lateral radiograph shows posterior displacement of epiphysis with no radiographically visible osseous fragments.
Epiphyseal separation of proximal phalange with a small metaphyseal osseous fragment
Epiphyseal separation of medial epicondyle of distal humerus Normal elbow joint
Distal metaphysis of radius
Within 2cm of articular surface
Dorsal displacement & apex anterior angulation
Radial dispacement & shortening
Concomitant fracture of styloid process of ulna
Concomitant dislocation of distal radioulnar joint
Colles fracture with concomitant fracture of styloid process of ulna and dislocation of distal radioulnar joint
A transverse metaphyseal fracture of the distal humerus
Commonest elbow fracture in childhood
Extension type: transcondylar fracture with posterior and proximal displacement and apex anterior angulation (95%)
Flexion type: anterior displacement and apex posterior angulation
Fat pad displacement indicating a joint effusion
Supracondylar fracture with posterior displacement of distal fragment and slight apex anterior angulation
Supracondylar fracture with minimal displacement
fat pad displacment
Wedge-shaped vertebral body with anterior part being compressed
Increased-density line instead of the fracture line
Adjacent vertebral discs intact
Stable lesion unless more than 30% compression
Compression fracture of C6 vertebral body
Compresion fracture of T12 vertebral body with kyphosis
Caused by axial compression, which drives the vertebral disc into the vertebral body below it, causing it to shatter.
It is an unstable lesion. The prognosis depends upon the displacement of the posterior aspect of the vertebral body and whether the vertebral arches are intact.
CT is of considerable value in evaluating the posterior elements, classifying injuries, and determining the site for vertebral decompression. CT scanning is also able to identify small cortical breaks.
MR is valuable in detecting injury of spinal cord and ligament.
Comminution fracture of vertebral body with posterior displacement of fracture fragments. Right posterior elements are also involved.
T 1 WI T 2 WI Fracture of L2 vertebral body with injury of adjacent spinal cord
Tumor and tumor like lesions
Malignant tumor with ability to produce osteoid or immature bone directly from neoplastic cells
Of unknown etiology = primary (majority )
Secondary to predisposing factors (Paget disease, bone infarct, radiation) = secondary
Age: second and third decades of life (children and adolescents)
Metaphysis of long tubular bone
Femur(40%), tibia(16%), and humerus(15%)
Soft tissue mass, pain, swelling, warmth, and restriction of motion
Increased serum alkaline phosphatase
Early metastasis: lungs , bones and other sites
The pattern of osseous involvement depends to a large extent on the amount of immature bone produced by the tumor. A mixed pattern consisting of both osteolysis and osteosclerosis is most typical, with purely osteolytic or osteosclerotic lesions being encountered less frequently.
Radiograph shows a lesion with osteosclerosis and osteolysis. Note the Codman triangle( ). Osteosarcoma on the upper third of tibia (mixed pattern)
Ill-defined intramedullary, metaphyseal lesion
Formation of immature bone by tumor
Soft tissue mass
Aggressive periosteal reaction:
Osteosarcoma on the lower third of femur (osteosclerotic pattern)
Radiograph shows ivory-like appearance. Osteosarcoma on the femur (osteosclerotic pattern)
Osteosarcoma of the femur (osteosclerotic pattern) with multiple pulmonary metastases
Osteosarcoma on the lower third of femur (osteolytic pattern) Radiograph shows bone destruction in the distal metaphysis and diaphysis of the femur, with soft tissue mass and Codman triangle( ).
Radiograph shows a lesion with both osteolysis and osteosclerosis on the upper metaphysis of tibia. Soft tissue mass ( ) is evident. Osteosarcoma on the upper metaphysis of tibia (mixed pattern)
Conventional radiograph is essential in establishing the specific diagnosis of osteosarcoma, but often cause underestimation of the extent of the tumor, both within and outside the bone.
Other imaging techniques
CT and MR imaging are more useful in defining the extent of tumor and its relationship to surrounding neurovascular structures and in evaluating the response of the tumor to therapy.
Intramedullary and soft tissue extent
Lesions in complex osseous structures such as pelvis, scapula, or spine
Other imaging techniques
Osteosarcoma on the lower third of femur
Signal: Low on T 1 WI and high on T 2 WI
Detecting skip lesions
Superior to CT in defining the intraosseous and extraosseous extent of the tumor
Other imaging techniques
synchronous foci of tumor that are anatomically separate from the primary lesion and that occur within the same bone or on the other side of a joint
T 1 WI T 1 WI T 2 WI +C Osteosarcoma on the upper third of tibia
Osteosarcoma with skip lesions
Producing osteoid or immature bone directly
Affects patients in their teens and twenties
Favors the metaphysis of long tubular bone
Plain film : essential for diagnosis
Bone destruction, formation of immature bone
soft tissue mass, aggressive periosteal reaction
Other modalities : determining extent of disease
Locally aggressive neoplasm composed of osteoclast like giant cells, usually involving the end of mature long bone
Etiology : Unknown
Staging : Latent, Active, Aggressive
Giant cell tumor of bone
Age: 20~40 years
Gender: F: M=2:1
Ends of mature long bone
Knee joint and distal end of radius
Pain and swelling at affected area
Pathologic fracture in 30%
Limited range of motion of adjacent joint
Pulmonary metastases :1-2%
GCT of radius
Expansile, lytic epiphyseal lesion extending to subchondral bone, with well-defined margins
Periosteal reaction and sclerotic rim: uncommon
Without calcification or ossification
Peripheral trabeculae — multi-locular appearance
Radiographs show a well defined lytic lesion at upper end of tibia with pathological fracture ( ). There is no sclerosis, no periosteal reaction, and no calcification GCT of tibia
Pathological fracture Fracture occurring at a site of previous abnormality, often by means of a stress that would not normally cause fracture.
GCT of tibia
Radiographs show expansile and lytic lesion with cortical break through and formation of soft tissue mass ( ). GCT of radius
Soft tissue attenuation, foci of low attenuation
Breakthrough of cortex with soft tissue invasion
Low-intermediate signal intensity on T1WI and T2WI
GCT of femur
T 1 WI T 2 WI T 1 WI T 2 WI ＋ C GCT of tibia
Locally aggressive neoplasm
Favoring the ends of mature long bones
Occurring most frequently in 20-40
Imaging findings : expansile, lytic epiphyseal lesion extending to subchondral bone, without calcification or ossification
Definition: Fluid containing lesion of bone, lined by mesenchymal cells Etiology: tumor like lesion of unknown etiology, attributed to local disturbance of bone growth Simple bone cyst
Metaphysis, migration to diaphysis with growth
Humerus and femur
Age: children and adolescents
Most lesions asymptomatic
Pain, swelling, stiffness at closed joint
66% of cysts present with pathologic fractures
Inactive, latent after skeletal maturity
Spontaneous regression in some cases
Simple bone cyst at upper third of humerus with pathological fracture
Spine, pelvis, ribs, skull, femur and humerus, etc
Involvement of bones distal to knee and elbow rare
Clinical presentations ：
Pain, pathological fracture, etc.
Osteolytic pattern: multiple poorly defined or well defined osteolytic bone destruction, perhaps with soft tissue mass or pathological fracture, usually without periosteal reaction; destruction of pedicle and vertebral body with intact intervertebral space.
Osteolytic metastasis M Radiograph shows osteolytic bone destruction at upper third of humerus, lateral end of clavicle with formation of soft tissue mass.
Multiple round bone destruction in the skull without sclerosis Osteolytic metastasis
Osteolytic destruction of left 5, 6 rib with formation of soft tissue mass Osteolytic metastasis
Osteoblastic pattern: multiple round or patchy radiodense lesion, or diffuse increased density
Mixed pattern ： osteolytic + osteoblastic
Radiograph shows multiple round or patchy radiodense lesion in the pelvis and lumbar spine. Osteoblastic metastasis
Radiograph shows diffuse increased density in pelvis, vertebral body of lumbar spine and upper third of bilateral femurs Osteoblastic metastasis
Diffuse increased density in vertebral body of L2, L4, L5 , sacrum and ilium. Osteoblastic metastasis
Mixed pattern of skeletal metastasis
Comparison of benign and malignant bone tumors Common, ill defined Uncommon, well defined if present soft tissue mass Various pattern, destruction by tumor Uncommon, secondary to pathologic fracture, without destruction by tumor Periosteal reaction Ill defined and infiltrative bone destruction, break through of cortex, immature bone produced by tumor Well defined bone destruction, thinning of cortex without interruption Osseous changes Rapid, invasion of adjacent tissue, metastasis Slow, compression and displacement of adjacent tissue, without metastasis Growth Malignant tumor Benign tumor Items