MSK Flashcards
Small, rounded bones located in tendons
Sesamoid bones - “accessory ossicles”
more dense white area along the edges of the long bone
cortex
very outside part of cortex (white part)
Periosteum
bunnies of bone activity resorbers
osteoclasts resorbers : remove, destroy: decrease density, lucent appearance
Can remove bone at_____of formation
20x rate
responsible for abandoning ship and letting tumor spread in bone
osteoclasts
Reparative cells that heals fx’s
Osteoblasts - slower
indications of long bone XR
Trauma, pain, edema, decreased ROM, FB
what views are mandatory in long boned which ones are alternative
Always at least AP, Lateral (orthogonal views - 90°) Oblique is initial 3rd view (hand, wrist, ankle, foot, etc) ○ Special views
lateral
operative
axial of the calcaneus
sunrise view of the patella
3 special views ordered
Comparison views” - image of the other side
● “Weight-bearing view” - AC joint, foot (ex: pt holds a weight to stress shoulder joint to expose abnormality)
● Perpendicular - axial plane (sunrise and axial)
CT scan indications
Complex fractures – characteristics, extent
● Pre-op evaluation
● Occult fracture
● Associated injuries
● Spinal column
● Tumors, infection
● Biopsy, interventional procedures
occult fractures
difficult to see on plain scan but suspected due to inability to weight bear
MRI indications
best for soft tissue
● Spinal cord injuries → MRI is imaging of choice*
● Occult fractures – hip (elderly), scaphoid ESP. if you can’t see on CT
● Tendons/Ligaments/Soft Tissue
○ MR Arthrography - contrast study of joints
○ Pre-op evaluation
● Certain complex fractures, infections
● Bone marrow abnormalities
● Avascular necrosis
T1 or T2
T1 because of black fluid
Bone Scans – Nuclear Med: Indications
Occult Fractures
● Stress Fractures
● osteomylitis (Bone Infection)
● Avascular Necrosis
● Osteomyelitis
● Malignancy
AABC’s of film reading
○ A dequacy
○ A lignment
○ B ones + Periosteum
○ C artilage (joint space can’t actually see catrilage)
○ S oft tissue
adequacy of plain film
● Name, date, L&R label, all views?
● Pt properly positioned
○ “True” lateral or “true” oblique?
○ All structures seen in anatomical alignment?
○ Special views taken properly?
● Must know normal radiographic anatomy to evaluate normal alignment and position
● Ex: forearm film is adequate if it includes both elbow and wrist joints!
anterior humoral dislocation
Torus fracture
lacks smooth margin
Impaction fx caused by falling, commonly missed fx in peds
Torus
system for looking at XR for fractures “B” of AABCS
Fractures = lucent (black) line passes through cortex
○ Check entire cortical margin for disruption
○ Check for impaction (bulge, increased density)
○ Acute Fx’s linear, jagged - edges not corticated
○ Fx’s should be visible on more than one view
● Decreased density (lucency, osteopenia)?
● Increased density (opaque, sclerosis, impaction)?
○ Generalized process or focal process?
reasons for widening of joint soaces
Widening: disruption, calcification, fluid (effusions)
name for a fracture extends into the joint
intra-articular Fx
Narrowing of a joint implies
Narrowing of a joint implies abnormal thinning of cartilage.
best imaging for ligamentous injury, disruption
MRI best for ligamentous injury, disruption
intra-articular Fx
Check if fracture extends into the joint
causes of decreased joint space
Arthritis - most types (condition of “bone on bone”)
○ Impacted fx, dislocation
usually need replacement
reasons for Increased joint space:
Fracture, dislocation
○ Hemarthrosis
○ Infection (pus)
what can we visualize in the soft tissue of plain film
● Edema
● Effusions in joint
● Fat pad - blood or fluid in fat space (elbow)
● Calcifications in soft tissue - outside of bone, joint
● Masses
● Gas
● Foreign bodies
effusion or increased fluid in joint space
gas in soft tissue need emergent amputation
mets from prostate
what are we worried about with GENERALIZED increased density
○ Multiple/diffuse osteoblastic metastases – prostate CA (classic!)
○ Osteopetrosis (“marble bone dz”)
FOCAL increased density of bone suspect
Impacted fracture, fracture healing
○ Localized osteoblastic metastases
○ Avascular necrosis
Late finding
May see “crescent lucency” from a subchondral fracture
○ Paget’s Disease
phases of pagets and what bones are typically effected
Phases: Early lytic, Mixed, Osteoblastic
● Dense, sclerotic bone changes late
Pelvis, skull, spine, tibia (spares fibula)
caharcteristic findings of pagets
GENERALIZED lucency suspect
Osteopenia
○ Osteoporosis
○ Endocrine/metabolic disorders, steroids (chronic use)
○ Hyperparathyroidism, osteomalacia, rickets
○ Multiple Myeloma (disseminated form)
FOCAL lucency suspect
○ Osteolytic metastases, bone cysts , some tumors
○ Multiple Myeloma (solitary form)
○ Osteomyelitis
look at how thin the boens are here
Risk for pathologic fracture
Decreased bone mass: generalized characteristic of osteoperosis
who gets osteoperosis
F> M, elderly, post-menopause, ETOH, steroids, smokers, renal failure, GI Dz, debilitation
what should you order in a pt with suspected osteoperosis
Plain film, BMD (bone mineral density test / DEXA (dual energy xray absorptiometry), CT
● Risk for pathologic fracture
story behind hyperparathyroidism
○ Stones, bones, abdominal groans
classic finding with hyperparathyroidism
hour glass
“brown tumors”, “salt & pepper skull”
_________ respond to periosteal insult - localized ○ Fx is a periosteal insult
Osteoblasts respond to periosteal insult - localized ○ Fx is a periosteal insult
non aggressive solid periosteal reaction
Fx healing, repetitive trauma (child abuse)
○ Neoplasms (usually benign)
○ Osteomyelitis, indolent infections
periosteal insult
Codman’s Triangle
Codman’s Triangle
Characteristic of aggressive periosteal reaction
Usually d/t malignancy ; also seen with osteomyelitis
Spicule of bone at edge of lesion, lifts periosteum
Forms a triangle with bone cortex
heel bone spur
4 Characteristics of Osteoarthritis (DJD)
Narrowed joint spaces
Osteophytes & Spurs (early OA)
Subchondral sclerosis (late OA)
Subchondral bony cysts
3 characteristics of charcot’s joint and who get’s them
○ Denervation of joint
○ Micro fx’s, bone fragmentation
○ Joint destruction
○ DM’s most common
CCPD
CPPD = Calcium Pyrophosphate Deposition Dz Two Types:
■ Chondrocalcinosis
■ Pseudogout – red, swollen joint
CPPD
2 types of DJD and MC
Osteoarthritis (DJD)
○ Primary most common
○ Secondary
Usually after trauma
Young, unilateral
what should you always say about joint issues
could be septic! but probably not b/c …
Risks for Septic - pyogenic
IVDU, trauma, prosthesis, steroids
fast septic joint
Septic - pyogenic
charcateristics of pyogenic septic joint
Monoarticular - knee, hip, hands - any joint
● Staph, GC
● Articular cartilage destruction
● Rapid progression
cc of Septic - non-pyogenic joints
M. tuberculosis, fungus
risks for non-pyogenic spetic joint
: IVDU, DM, steroids, TB risks
ulnar deviation classic finding in
RA
RA charcteristics
○ Narrowed joint spaces
○ Periarticular erosions
○ Osteopenia ○
○ Subluxation
○ Also radiocarpal erosion and ulnar deviation
● Psoriatic arhtritis charcateristics
○
At DIP, spares PIP
Subchondral erosions
Terminal phalanges narrow “pencil in cup”
Bamboo spine ”
syndesmophytes fuse anteriorly
seen in Ankylosing Spondylitis
order of fusion in Ankylosing Spondylitis
SI joint fuses first - ascends spinal column
three classic findings with Ankylosing Spondylitis
Sacroiliitis is hallmark
HLA-B27 positive
bamboo spine
what do we measure to tract Ankylosing Spondylitis
measure distance angle
Ankylosing Spondylitis seen most commonly in
young men
what to ask with bone tumors
○ Where? Joint violated? ( tumors don’t cross joints )
○ Margin? Sclerotic/thin, well-defined vs. irregular, ragged
○ Shape? Longer than wide (w/in medullary) or wider than long (burst through cortex)?
○ Characteristics? Geographic, permeative, “moth-eaten”, expansile, “soap bubbly”
○ Bony reaction? Lytic, sclerotic
○ Periosteal reaction?
■ Codman’s, mixed, onion skin
BAMBOO SPINE (AS)
“moth-eaten”, expansile, “soap bubbly” all describe
bone tumors
bone tumors seen in 0-10 yrs
Ewing’s sarcoma
○ Neuroblastoma
● 10-20yo , long bones tumors ddx
○ Ewing’s sarcoma (shaft)
○ Osteosarcoma (epiphysis: growth areas)
20-40 ddx bone tumor
○ Osteosarcoma
○ Giant cell tumor (epiphysis)
>40 yrs ddx for bone tumors
Chondrosarcomas
■ (hips, pelvis, humerus 75%)
Consider metastases from distant primary
osteosarcoma of distal femur
Description of Fractures
oepn or closed
location
number of fragmnets
direction
alignment
special fractures
open fracture means
compound (bone out through the skin of wound over broken bone)
gunshot wound breaking femur
depressed
how to describe the location of a fx
Which bone(s)?
○ Where in the bone?
○ “Head” proximal (usually)
○ Proximal, middle, distal third of shaft, neck
○ Intra-articular or not?
direction of fx
Transverse, oblique spiral, longitudinal
transverse spiral fracture
oblique
longitudinal fx
greenstick
spiral fx
vaLgus
forms an L
Varus
how to talk about alighnment
descirbe the movement of the distal piece
angulation
NOT DISPLACEMENT
forms an angle
still touching althoguh displacement can also still be touching
can have both
describe angulation in degrees and displacement %
movement away from
mid-diaphyseal axis line
Displacement
how to describe angulation
Posterior (dorsal) or Anterior (ventral/volar)
Medial (varus) or Lateral (valgus
dorsal
can bet the back of the dog
Closed oblique fracture of the right distal 5th metatarsal shaft with medial displacement (of 5th metatarsal)
medial displacement of the DORSAL segment
Right humerus with a spiral fracture at the mid-shaft with 90% medial displacement, 1-2cm shortening and internal rotation of distal segment
still touching but hooked on an edge
Spiral fracture of the left distal tibia that is intra-articular and comminuted (many pieces), with a comminuted oblique fx of the distal fibula with ~1cm shortening. Both with varus angulation.
Greenstick fx of the right mid-clavicle with 60 degree volar angulation. There is disruption of the AC joint w/ inferior displacement of the distal clavicle
Complete POSTERIOR (describes foot) dislocation of the right tibio-talar joint. There is also a spiral fx of the distal fibula with shortening and lateral displacement of the distal fragment
comminuted (multiple) fx of the left proximal tibia and tibial plateau (all the way up) , with an intra-articular fx extending through the lateral tibial spine. There is an opacified area medially – likely an area of impaction.
goes to CT
seaweed taken a piece of the rock
AVULSION beach
nondisplaces avulsion fx at tge base of the 5th metatarsal left foot
avulsion fx’s are caused by
caused by sudden torque on the ligaments
igament stays intact but pulls a piece of bone away. If small piece of
bone pulled off, commonly called a “chip fracture.”
nutrient vessel doesn’t break through the cortex and is not compliteley longitudinal
FAKE OUT
acessory ossicle fakeout
esamoid bones/ Accessory Ossicles typically found in
Feet, hands, elbows, wrists, knees
growth plate fakeout wiht kids
normal pelvis of a child
complications with compound fx
Any fracture complicated by breach in the adjacent skin
● High incidence of infection , osteomyelitis (later)
what are we worried about wiht crush injuries
Crush injury: vascular complications, infection
what needs to happen with open practures
Irrigated and repaired in OR < 8 hrs (orthopedic emergency!)
Antibiotics, Tetanus
exception to OR rule for compound fractures
Open tuft fx (exception to OR repair) → wash out, close f/u
what are Stress Fractures
Small breaks, repetitive stress, exercise or impact
stress fracture most common in
Most common in the foot (usually at 2nd metatarsal), lower leg
who gets stress fractures
elderly, gymnasts, athletes, new marine recruit, ballerina, goalies
what do you normally see with a stress fracture XRAY
what are alternative iimaging options
○ Plain xray may show findings in 10-14 days (or longer)
○ Repeat xray - solid periosteal reaction in 10-14 days
● Bone scan - may be positive in 6-72 hours
● MRI
a fracture arising within abnormal bone is termed
pathologic fx
processes associated with pathologic fractures
○ Bone tumor
○ Bone cyst
○ Metastasis
○ Lytic or sclerotic changes
Intra Articular Fractures
● Fracture enters joint
● Important distinction
● Cartilage damage
● Ligamentous injury
● Joint is now at risk for degenerative arthritis
SEE ONE SAY IT BECAUSE THEY GET SPECIAL TREATMENT
intra articular Barton’s
fx that are easy to miss
Stress fracture (March fx)
● Scaphoid, elbow, radial head, midfoot, tibial plateau, hip; supracondylar and torus fractures in kids
● Non-displaced and impacted fractures
● Non-displaced growth plate fractures (SALTER 1)
Suspect fracture but negative x-ray?
○ Dx: Probable fx. Immobilize
○ Repeat x-ray in 2-3 weeks – look for callous
○ CT, MRI or bone scan next
blasts will show up later
5-7 day fracture healing
Inflammatory Phase – 5 to 7 days, hematoma formation
4-40 say fracture healing
Reparative Phase – 4 to 40 days, callus formation
Remodeling Phase of fracture healing
remodeling Phase – can last up to one year, callus is converted into bone, 70% of healing time
ORIF
= open reduction and internal fixation
○ Plate, screws, sutures
Fracture Complications
● Acute (hours/days)
Compartment Syndrome
■ Pulselessness, pallor, pain, paresthesia, paralysis (5 P’s)
○ Local Infection - skin cellulitis
○ Fat Embolism
○ Hemorrhage
Delayed (weeks/months) complications
Delayed union, Malunion, Nonunion
‘Malunion’ is a complication that arises if a fracture is allowed to heal in an abnormal position.
Failure of bone healing following a fracture is termed ‘non-union’ .
○ Osteomyelitis – bone infection
○ Avascular necrosis – the death of bone cells through lack of blood supply
○ Myositis Ossificans – after blunt trauma
imaging and diagnostic tests for osteomyelitits
● MRI best , bone scan next
● Bone biopsy diagnostic
cna be acute subacute or chronic
● Soft tissue swelling, Hx
● Focal lucent or destructive areas within the bone
● Focal periosteal reaction
Osteomyelitis
AVN occurs
AVN occurs in 15-30% of scaphoid
fractures, almost always involving proximal pole. The more proximal the fracture line, the greater the risk of AVN.
what would you order if trying to look at the soft tissues
MRI
What would you order if you suspect a malignancy or oseomylitis
bone scan
what would you order if you suspect avascular necrosis
MRI
what would you order if you suspect a stress fracture
bone scan
What are the four subgroups of erosive arthritis
rhematoid
gout
psoriatic
AS
narrowed joint spaces
periarticular erosions
osteopenia
and subluxation
all pictures of
rheumatoid
Psoriatic arthris at _____ but spares the ____
at DIP but spares PIP
sharp sclerotic punched out rat bite erosion near affected joint
GOUT
radioculpar erosion with ulnar deviation
RA
HLA-B27 positive is a finding in
AS
what test imaging is best for dx osteomyelitis (1st and then 2nd)
what is diagnostic
MRI
then bone scan
bone biopsy is diagnostic
diagnostic test of choice for AVN
MRI
and then bone scan
plain film sensitive is late
extra skeletal ossification in soft tissue
occurs after blunt trauma but can be after penetrating tauma this is a young kid thing
what is myosisitis ossification
