RADIO NONTRAUMA ABN of APPENDICULAR SKELETON

what are conventional radiographs good for?

visualization of bone cortex

disadvantages of conventional radiograph

can't visualize entire circumference of bone in a single shot; not sensitive for demonstrating MSK abn (it CAN detect soft-tissue swelling if it is SIGNIFICANT)

what is a good imaging modality to visualize BM & soft tissues, muscles, tendons, ligaments?

MRI

bone density

amount of bone mineral (Ca2+ phosphate) in bone tissue (matrix)

what do osteoclastic & osteoblastic activity rely on?

viable blood supply

what does bone respond to?

mechanical forces (repeated use, trauma, overuse)

example of diffuse, increased density

diffuse osteoblastic metastases sclerotic

examples of focal, increased density

localized osteoblastic metastases/tumor, AVN of bone, Paget's Disease, CPPD

examples of diffuse, decreased density

osteoporosis, hyperparathyroidism

examples of focal, decreased density

localized osteolytic metastases, multiple myeloma, osteomyelitis

bone metastases

m/c than primary bone tumors, usu widespread

m/c/c of osteoblastic mets in older men

prostate CA (multiple>single)

AVN of bone

poor blood supply --> cell death --> collapse of bone

how does AVN appear in later stages?

INCREASED DENSITY

where does AVN m/c occur?

scaphoid in wrist, femoral head, humeral head

what is the most sensitive modality for detecting AVN?

MRI

causes of AVN

Intravasc: sickle cell & PCV

Vasc: vasculitis (lupus & radiation induced)

Extravasc: trauma (frx)

Idiopathic: exogenous steroids, cushings, legg-calve-perthe disease (delayed bone growth by time child is 2 is 1st presentation)

crescent sign

occurs when surface of articular surface is flattening (DO NOT MISS! PRECURSOR TO WORSENING DISEASE!)

pictured: AVN of femoral head

Paget's Disease

chronic disease of bone, m/c in older men; characterized by varying degrees of inc bone resorption & inc bone formation

will affect spine & pelvis; can dx by pain & XR alone

imaging hallmarks of Paget's

thickening of cortex & coarsening and thickening of trabecular pattern

Paget's imaging

CPPD imaging

Ca2+ pyrophosphate disease- causing hook shaped deformity along 2nd & 3rd metacarpal head from osteophyte

Osteoporosis

skeletal disorder characterized by LOW BMD (postmenopausal & age related bone loss)

focal lesions

geographic local pattern of bone destruction

mottled local pattern of bone destruction

"moth eaten appearance"

permeative local pattern of bone destruction

Multiple Myeloma

m/c primary malignancy of BM in adults; dec density & patchy areas of lytic lesions

disseminated

multiple, small sharply circumscribed (described as "punched out") lytic lesions of approx the same size

what is MM associated w/?

diffuse spinal osteoporosis (hallmark) & multiple compression fractures @ end stages

osteomyelitis

hallmark on radiograph is destruction of articular cartilage, release of synovial fluid; monoarticular; rapidly progressing infx; MRI>XRAY for Dx

WHAT CAN BOTH INC OR DEC DENSITY ON XRAY? *Rule Breaker*

ARTHRITIS

arthritis

affects a joint & bones on either side, almost always accompanied by joint space narrowing

joint disease>bone disease

hallmark of hypertrophic arthritis?

osteophyte formation

3 major types of arthritis

OA/DJD, erosive, infectious

OA/DJD

bone formation @ involved site, may occur w/in confines of bone (subchondral sclerosis) or protrude from bone (osteophyte)

m/c OA/DJD

primary osteoarthritis AKA degenerative joint disease

m/c/c of OA/DJD

mechanical stress or excessive wear & tear in weight bearing joints

erosive arthritis

inflamm & synovial prolif (pannus formation), production of lytic lesions in or near joint

(erosion)

types of erosive arthritis

RA, gout, psoriatic arthritis, ankylosing spondylitis

RA

m/c in F; involves proximal joints of hands & wrists, usu B/L & symmetric

late findings of RA

ulnar deviation of fingers @ MCP, subluxation of MCP & ligament laxity leading to swan neck & boutonniere's deformities

gout

inflammatory changes incited by deposition of calcium urate crystals in the joint

M>F

monoarticular; asymmetrical later in course

what joint does gout m/c affect?

metatarsal phalangeal of the great toe

hallmark of gout

sharply marginated, juxtaarticular erosion that tends to have sclerotic borders ("rat bites")

gout imaging

psoriatic arthritis

characterized by erosion & new bone formation that may occur in the same joint

"Pencil in a cup" appearance

psoriatic arthritis imaging

ankylosing spondylitis

young, males

neck/LBP, worse @ night & better w/ exercise

what is ankylosing spondylitis associated w/?

ulcerative colitis

what marker can do patients w/ ankylosing spondylitis test + for?

HLA-B27

hallmark of ankylosing spondylitis

fusion of lumbar spine & sacroiliac joints (sacroilitis)

bamboo spine ("dagger sign" on AP projection)

ankylosing spondylitis; no spaces b/w vertebrae

normal C/S

lateral spine xray

AP spine xray

oblique spine xray

normal thoracic spine xray

normal L/S xray

white arrows: 2 pedicles on side of vertebral body

white dotted arrow: spinous process

black arrow: facet joint

scottie dog sign

seen on oblique views; "the best dog in medicine"

DDD (degenerative disc disease)

disc becomes dehydrated & degenerates with increasing age; gradually leads to progressive loss of the height of the intervertebral disc space

compression fractures of the spine

common, W>M & typically 2/2 osteoporosis

how are compression fractures of the spine 1st noticed?

b/c of inc kyphosis or overall loss of body height

study of first choice for compression fractures of the spine

conventional spine radiographs

what parts of the vertebral body are usually involved in osteoporotic compression fractures?

anterior & superior aspects

spinal stenosis

narrowing of the spinal canal 2/2 soft tissue or bony abnormalities (either acquired or congenital; acquired>congenital)

where is spinal stenosis m/c?

cervical & lumbar areas

neurogenic claudication

intermittent pain & paresthesias radiating down the leg & worsened by standing or walking & relieved by flexing the spine by lying supine or squatting

what imaging is obtained 1st for spinal stenosis?

conventional radiographs

what is the imaging modality of choice for spinal stenosis?

MRI

fracture

disruption in the continuity of all or part of the cortex(hard outer layer) of a bone

incomplete fracture

only part of the cortex is fractured

complete fracture

through & through

normal xray of growing bone

type 1 salter harris fracture

through the growth plate; heals well w/ cast

type II salter harris fracture

through the growth plate & metaphysis; heals well w/ cast

type III salter harris fracture

through growth plate & epiphysis; can develop arthritic changes or asymmetrical growth plate fusion

type IV salter harris fracture

through all 3 elements: growth plate, metaphysis and epiphysis; more likely to develop early fusion of growth plate w/ angular deformities & shortening of bone

type V salter harris fracture

crush injury to growth plate; more likely to develop early fusion of growth plate w/ angular deformities & shortening of bone; associated w/ vascular injury & cause growth impairment

Klein's Line

arbitrary line drawn along superior edges of femoral neck; useful in detecting early slipped upper femoral epiphysis in adolescents; line should normally intersect lateral aspect of superior femoral epiphysis on AP view

what can salter harris fractures be a result of?

child abuse!

what injuries raise suspicion of child abuse?

metaphyseal corner fractures, rib fractures, head injuries

metaphyseal corner fractures

small avulsion fractures from repetitive mvmt of ligament over bone

rib fractures

especially more than 1 & posterior

metatarsal fractures

if not MVA, CHILD ABUSE!! (hard to break)