Lecture 2: Principles of Radiographic Investigation

Question 1

What are these parts of the bone?

Answer 1

E: Epiphysis: The end of the growing bone is known as the epiphysis. Initially comprised of cartilage there is gradual ossification that eventually fused with the shaft (diaphysis) of the bone.

P: Physis: Cartilage growth plate bw epiphysis and metaphysis is known as the physis. Also referred to as the epiphyseal growth plate.

Z: Zone of provisional calcification: At the junction of the physis and the metaphysis a thin line of increased density is identifiable. Represents area of calcification of the physis cartilage and is the precursor to bone formation.

M: Metaphysis: Between zone of provisional calcification and the diaphysis. Most metabolically active area of bone and as such often area for tumors and infection. In this area calcified cartilage is transformed into definitive weight bearing stress trabeculae. Once weight bearing the width becomes greater than the diaphysis.

D: Diaphysis: Lies between both metaphysis and is longest part of bone. Also known as the shaft, Note a thickened cortex (out part of bone) and decreased medullary space.

Question 2

Analysis of a bone lesion:

Answer 2

Position within bone

Site of Origin

Shape

Size

Margination (Zone of transition)

Cortical integrity

Medullary response

Periosteal Response

Lesions / Symmetry

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Question 3

What is the position of this lesion?

Answer 3

Diaphyseal

Question 4

What is the position of this lesion?

Answer 4

Apohyseal/apohysis

Question 5

What is the position of this lesion?

Answer 5

Epiphyseal

Question 6

What is the position of this lesion?

Answer 6

Epiphyseal-metaphyseal

Question 7

What is the position of this lesion?

Answer 7

Metaphyseal

Question 8

What are the different positions within bone a lesion can appear?

Answer 8

Apophysis: (analogous to epiphysis but site of muscular attachments) (in this case we see a chondroblastoma, an osteolytic(dark) lesion in the greater tuberosity of an 11 year old).

Epiphyseal Lesion: (well defined osteolytic lesion evident is distal tibial epiphysis of 7 yr. old, also chondroblastoma)

Epiphyseal - Metaphyseal lesion: (within lateral tibial epiphysis and metaphysis a sharply circumscribed abnormality is present: giant cell tumour)

Metaphyseal lesion: (An expansile osteolytic lesion occurs: aneurysmal bone cyst. Epiphysis is spared in this neoplasm)

Diaphyseal lesion: (Multiple sharply demarcated osteolytic lesions present throughout the diaphysis. Mote inner cortical destruction indicating medullary origin. A multiple myeloma).

Question 9

What are these sights of origin?

Answer 9

A and B: Medullary: Note central location, slight expansion, thinned but intact cortex. Diagnosis simple bone cyst.

C and D: Cortical: Note eccentric location, cortical destruction and periosteal new bone formation. Diagnosis Ewing’s sarcoma.

E and F: Periosteal: A dense soft tissue mass is dominant feature, with no evidence of bone destruction. Observe the thin separating, radiolucent cleft between the mass and cortex (arrows) indicating its extra cortical origin. Diagnosis periosteal Osteosarcoma.

G and H: Extraosseous: Well demarcated soft tissue lesion visible demonstrates cortical and trabeculae bone properties. Diagnosis traumatic myositis ossificans.

Question 10

Define imperceptible margins

Answer 10

Other terms used include poor, hazy or ill-defined margins, or a wide zone of transition. The gradation between the lesion and normal bone occurs gradually with no distinct demarcating line or change in density. This type of boundary is indicative of aggressive bone destruction as seen in infections and malignant tumours.

Question 11

Define sharp margins

Answer 11

Synonyms include definite and sclerotic margins or a narrow zone of transition. The interface between the lesion and normal bone is clearly define and may be outlines by a sclerotic line.

Question 12

Describe this lesions zone of transition

Answer 12

Moth eaten osteolytic lesion present in medullary cavity. Difficult to perceive where the lesion begins and ends which is typical of aggressive abnormality (Ewing’s sarcoma in this case).

Question 13

Describe this lesions zone of transition

Answer 13

Sharp Margination. This geographic lesion exhibits a conspicuous zone of transition accentuated by the sclerotic margins. Denotes a contained, slowly growing lesion (fibrous dysplasia).

Question 14

Describe this cortex

Answer 14

Thinning: There is extreme thinning of all visible cortices (pencil thin) and generalized demineralization of all bones present. Commonly seen in osteoporosis

Question 15

Describe this cortex

Answer 15

Thickening: The two cortices are grossly thickened, with compromise of the adjacent medullary space. Additionally bone is deformed and has transverse lucencies on its convex surface (pseudo fractures), all consistent with diagnosis of Paget’s disease.

Question 16

Describe this cortex

Answer 16

Expansion: Note the thin bulging but intact cortex of the proximal fibula. This represents continued endosteal erosion and periosteal deposition, with continued growth of the lesion. Diagnosis Aneurysmal bone cyst.

Question 17

Describe this cortex

Answer 17

Destruction: Disruption of the cortex is indicative of an aggressive bone lesion; in this case from metastatic carcinoma.

Question 18

Describe this cortex

Answer 18

Fracture: An oblique fracture line and disruption of the cortex is readily identifiable through a malignant lesion.

Question 19

Describe the different types of medullary response

Answer 19

Osteolytic: These are typified by their loss of localized bone structure and density. It is the subtle loss of bone density that is most difficult to perceive of all patterns of bone disease. Three patterns of radiolucent destruction are identified – geographic, moth eaten and permeative.

• Geographic: other terms are well circumscribed and uniformly lytic lesions. Usually solitary, > 1 cm and a sharper margin. In general are slower growing lesions, i.e. Least aggressive with narrow zone of transition.
• Moth Eaten: Multiple poorly marginated small or moderately sized lucencies are characteristic of this pattern. Frequently the margins of each lesion are ragged and irregular. This type of destruction reflects an aggressive abnormality with intermediate zone of transition.
• Permeative: Numerous tiny, pin hole sized lucencies (less than 1mm) constitute a permeative pattern. A wide zone of transition is evident. These lesions frequently overlooked because of their size, and with progression may enlarge enough to become moth eaten in character. Usually seen in the most rapidly aggressive malignant bone tumours.

Osteoblastic: These show increased density due to overproduction of bone or calcium laden tissue. These may be diffuse ivory-like or localized.

Mixed: Both lytic and blastic patterns are evident. Most common in mixed metastasis.

Question 20

Describe this medullary response

Answer 20

Geographic: other terms are well circumscribed and uniformly lytic lesions. Usually solitary, > 1 cm and a sharper margin. In general are slower growing lesions, i.e. Least aggressive with narrow zone of transition.

Question 21

Describe this medullary response

Answer 21

Moth Eaten: Multiple poorly marginated small or moderately sized lucencies are characteristic of this pattern. Frequently the margins of each lesion are ragged and irregular. This type of destruction reflects an aggressive abnormality with intermediate zone of transition.

Question 22

Describe this medullary response

Answer 22

Permeative: Numerous tiny, pin hole sized lucencies (less than 1mm) constitute a permeative pattern. A wide zone of transition is evident. These lesions frequently overlooked because of their size, and with progression may enlarge enough to become moth eaten in character. Usually seen in the most rapidly aggressive malignant bone tumours.

Question 23

What are the different types of periosteal response?

Answer 23

Solid: Defined by continuous layer of new bone that attaches to outer cortical surface. Typically related to a very slow form of irritation. Disorders include stress fractures, osteoid osteoma, venous stasis and hypertrophy osteoarthropathy.

Laminated: Also referred to as onion skinned. Most conspicuous feature is alternating layers of lucent and opaque densities on the external bone surface. At times only a single lamination will be visible. With time a laminated response may transform into a larger solid appearance. The significance of laminated response is varied, since it can be seen in slow and aggressive tumours as well as infections. Classic associated disorder is Ewing’s sarcoma.

Spiculated: Additional Terms include brushed whiskers and hair on end. The term SUNBUSRT has been used to describe radiating spicules of bone from a point source. Each spicule is separated from the other by an interposed radiolucent region. This pattern is indicative of a very aggressive bone tumour, often Osteosarcoma.

Codmans Triangle: First described by Ribbert in 1914, Codman associated the triangle of periosteal new bone at the peripheral lesion-cortex junction as due to sub-

Question 24

What is this type of periosteal response?

Answer 24

Spiculated: Additional Terms include brushed whiskers and hair on end. The term SUNBURST has been used to describe radiating spicules of bone from a point source. Each spicule is separated from the other by an interposed radiolucent region. This pattern is indicative of a very aggressive bone tumour, often Osteosarcoma

Radiating spicules of bone (arrows) characterise this aggressive Osteosarcoma.

Question 25

What is this type of periosteal response?

Answer 25

**Solid:** Defined by continuous layer of new bone that attaches to outer cortical surface. Typically related to a very slow form of irritation. Disorders include stress fractures, osteoid osteoma, venous stasis and hypertrophy osteoarthropathy.

Question 26

What is this type of periosteal response?

Answer 26

**Laminated:** Also referred to as onion skinned. Most conspicuous feature is alternating layers of lucent and opaque densities on the external bone surface. At times only a single lamination will be visible. With time a laminated response may transform into a larger solid appearance. The significance of laminated response is varied, since it can be seen in slow and aggressive tumours as well as infections. Classic associated disorder is Ewing’s sarcoma.

Question 27

What is this type of periosteal response?

Answer 27

**Sunburst Periosteal Response:** Periosteal spicules appear to radiate away from a point source. Diagnosis Osteosarcoma

Question 28

What is this type of periosteal response?

Answer 28

**Codman’s Triangle:** A triangular shaped periosteal new bone formation typifies this named response (arrows) and is a significant but nonspecific finding in many disorders including infection, neoplasm and trauma.

Question 29

What is this type of epiphyseal fracture?

Answer 29

**Salter Harris type 1:** Represents isolated fracture through the growth plate. Usually the radiograph appears normal, with the diagnosis being made clinically because of tenderness over the epiphyseal plate and soft tissue swelling.

Question 30

What is this type of epiphyseal fracture?

Answer 30

**Salter Harris type 2:** This is a fracture through the displaced growth plate, which carries with it a corner of the metaphysis. The metaphyseal fragment has been called the Thurston Holland sign. Most common epiphyseal injury, comprising approximately 75% of cases. The most common sites are the distal radius (50%), as well as the tibia, fibula, femur and ulna. The epiphyseal separation is usually easily reduced and a good prognosis is the outcome.

Question 31

What is this type of epiphyseal fracture?

Answer 31

**Salter Harris type 3:** The fracture line is directed along the growth plate and then turns towards the epiphysis. It results in intra-articular fracture that may require open reduction treatment. Most frequent site is the distal tibia.

Question 32

What is this type of epiphyseal fracture?

Answer 32

**Slater Harris type 4:** Obliquely orientated, vertical fracture that passes through the epiphysis, growth plate and metaphysis. The fracture fragment consists of a portion each of the metaphysis, growth plate and epiphysis. The most common sites are the lateral condyles of the distal humerus in patients under 10 yrs., and the distal tibia in those over 10.

Question 33

What is this type of epiphyseal fracture?

Answer 33

**Salter Harris type 5:** Least common and results from a compressive deformity of the growth plate. Initially, the radiographs are normal, until cessation of growth plate creates bone shortening or partial arrest, which leads to progressive angular deformity. Most common sites are distal tibial and distal femoral epiphyseal centres.

Question 34

What is a brodies abscess?

Answer 34

**Clinical:** Localized, aborted form of suppurative osteomyelitis. Mimics osteoid osteoma with localized limb pain, worse at night, dramatically relieved by aspirin. History of recent infection or surgery (dental). Most common in male children. Metaphysis in long bone usually distal and prox. tibia, distal femur, fibula and radius.

Question 35

What does a brodies abscess look like radiologically?

Answer 35

* Usually oval, elliptical with a halo or doughnut rim of heavy reactive sclerosis. * Radiolucency usually 1cm or larger. (osteoid osteoma smaller) * Osteoid osteoma and Brodies abscess cannot be determined radiologically.