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214 Cards in this Set

  • Front
  • Back

An avulsion of the ASIS apophysis is caused the pull of what muscle?


An avulsion of the AIIS apophysis is caused by the pull of what muscle?

Rectus Femoris
What is the most common type of hip dislocation?
posterior, secondary to a mvc. concerning regarding the sciatic nerve
What is a Judet view?
dedicated view to r/o an acetabular fx
What is Legg Calve Perthes Disease? When does it occur?
avascular necrosis of the femoral head. 4-8 yoa.

If you are concerned re a SCFE which view is it necessary to get?

Groin Lateral or a Billing projection
What does HADD stand for?
Hydroxyapatite deposition disease. a major cause of chrnic hip pain
What is a Jefferson fracture?
burst fx of C1
An insufficiency fracture of the sacrum is found in what 2 types of patients?
osteoporosis and pts who have had prior radiation to the pelvis
What study is best to visualize occult fractures?
MRI because it allows the identification of marrow fx lines
Whatt is Myositis Ossificans?
formation of peripheral calcification in a previously injured muscle
What is a Trough SIgn?
a lucency in the glenohumeral junctionwhich indicates impaction from a posterior dislocation

What is the difference in calcification between myositis ossificans and parosteal sarcoma?

Myositis Ossificans will have peripheral ossification/calcification.
What is a free or sequestered fragment?
when disk material migrates from the parent disc
What is a Tarlov Cyst?
an enlarged nerve root sheath, a nl variant. It may also be called a Perineural Cyst
What is a conjoined root?
congenital anomaly of 2 nerve roots exiting the thecal sac together instead of separately. a conjoined root will have a lower density than the thecal sac
What is a lateral disc and why is it clinically important?

It is a disc protrusion that occurs lateral to the neuroforamen. it can irritate a nerve root that has already exited the foramen and will mimic a disk protrusion at a higher level.

What are the 2 tyes of Spinal Stenosis?
Congenital and acquired
Who gets Congenital Spinal Stenosis?
Achondroplastic Dwarfs, Morquio's Disease
What are the 3 types of Spinal Stenosis?
central canal, neuroforaminal, lateral recess
What are the 2 most useful CT findings to diagnose spinal stenosis?
obliteration of the epidural fat and flattening of the thecal sac
Name some aquired causes of spinal stenosis?
hypertrophy of ligamentum flavum, pagets, ossification of the posterior longitudinal ligament,diffuse idiopathic skeletal hyperostosis
What are the MC cause of Neuroforaminal Stenosis?
DJD, Osteophytes
What is Spondylolisthesis?
anterior displacenebt of a cephalad vertebral body with respect to a caudad vertebral body
What is the grading for Spondylolisthesis?
I-25%, II 25-50%, III 50-75%, IV 75-100%
What is Spondylosis?
degenerative disease at the facet joints
What is Spondylolysis?
Pars Interarticularis defect
What is Osteitis Condensans Ilii?
triangular-shaped aareas of slerosis noted in the iliem of the SI joint
What is Osteitis Pubis?
historically infection of the pubic symphysis after bladder surgery
What is the typical bony finding in Multiple Myeloma?
"swiss cheese"
What is the differential diagnosis of a sequestrum on CT?
Eosinophilic Granuloma, Osteomyelitis, Desmoid, and Osteoid Osteoma
What is the significance of a sequestrum?
Antibiotics do not suffice because the sequestrum doesn't have a blood supply and antibiotics can't reach it
What is a helpful sign of bony metastisis?
permeative appearance which suggests a marrow based process
What are Scmorl's Nodes?
herniation of disc material through the end plate of a vertebral body
What are Tarlov Cysts?
nerve sheath dilitations whose densities are similar to csf
What are the CT findings in Paget's Disease?
cortical thickening,bone overgrowth 2 findings not seen in Multiple Myeloma
What is Fibrous Dysplasia?
a congenital disorder of bone growth leading o fibrous tissue, chondral tissue, and cysts within bones. usually an incidental finding. never has periostitis, malignant transformation, or is painful.
How do you make the diagnosis of patella alta?
using the Insall and Salvati method. Patella tendon lenth/patella lenght if >1.2, if <0.8 Patella Baja is present
What is the Fabella?
sesamoid bone, located in the lateral head of the Gastrocnemius muscle
What are the attatchments of the ACL?
the lateral femoral condyle withn the intercondylar notch and the anterior intercondylar eminence of the tibia
What are the attachments of the PCL?
the medial femoral condyle within the intercondylar notch and the posterior intercondylar eminence of the tibia
Where is the peroneal nerve located?
adjacent to the head of the fibula
What is a housemaid's knee?
Prepatellar effusion
Tibial plateau fx usually result from what kind of blow to the knee?
Lateral, valgus blow
What is the most common side for tibial plateau fx?
What is the %age popliteal artery injury in a knee dislocation?
What is the Sleeve fracture of the patella?
occurs in children, a portion of the lower cartilage is avulsed from the lower pole
What is Blount's Disease?
Infantile Tibia Vara, breaking or fragmentation of the medial tibia metaphysis with medial angukation of the leg
What is a Valgus Deformity?
when the distal segment of the joint is displced laterally
What is Osgood Schlatter's Disease?
tractional injury at the tibial tubercle at the patellar tendon insertion site. occurs in kids who recently had a growth spurt
What is Pellegrini-Stieda Calcification?
it is a dystrophic response to a damaged medial collateral ligament, near the medial condyle of the tibia
CPPD, Calcium pyrophosphate dihydrate depostion seen at the periphery at the medial and lateral joint spaces
What is Osteochondritis Dissecans?
separation of the rticular surface of the medial femoral condyle
What is a Cortical Desmoid?
nl pediatric variant lucency involvong the pos-medial aspect of the distal femoral metaphysis
multiple myeloma?
most common primary malignant neoplasm of bone
50-70y; M:F 2:1
symptoms: vague bone pain of progressive severity, fever, anemic sxs
complications: pathologic fractures
solitary plasmacytoma: solitary osseous focus of MM (uncommon)
x-ray findings:
loss of bone density - from diffuse marrow involvement
"punched out" lesions - esp. skull, long bones
diffuse bone destruction - esp. pelvis, sacrum
invasion of soft tissues - often paraspinal, extrapleural mass
osteosclerosis - very rare
metastatic calcifications - particularly kidneys, occ. lungs
NB: does not involve pedicles of spine
Maisonneuve fracture
fracture of the proximal third of the fibula
rupture of the distal tibiofibular syndesmosis
associated with:

fracture of the tibia
rupture of the deltoid ligament
caused by an ABDUCTION and EXTERNAL rotation force applied to the ankle which forces the talus laterally against the fibula
Schmorl node
chondrification defects where periosteal vessels penetrate cartilage plates of disc

concave defects at upper and lower vertebral endplates with sharp margins produced by herniation of disc material

similar signal intensity as disc
low signal intensity of rim
associated with narrow disc space

Scheuermann disease
neuropathic (Charcot) joint
M > F
age > 40 yrs

6 D's
increased density


diabetic neuropathy
syphilis (tabes dorsalis)
meningomyelocele / spina bifida
nerve injury: spinal cord or peripheral nerves
congenital insensitivity to pain
Charcot-Marie-Tooth syndrome
resembles fibrous dysplasia
occurs primarily in the tibia and jaw
McCune-ALbright Syndrome
polyostotic fibrous dysplasia
precocious puberty
multiple lesions of fibrous dysplasia in the jaw
lytic lesion in phalanges
usually containscalcified chondroid matrix, but not in the fingers
not usually painful if painful think chondrosarcoma
pathologic fractures
Bone Infarct
well defined densely sclerotic serpiginous borders
Ollier Disease
multiple enchondromas
Maffucci Syndrome
multiple enchondromas associated with soft tissue hemangiomas
increased incidence of malignant degeneration
Eosinophilic Granuloma
form of histiocytosis X
exclusively in pts < 30 yoa
mention in any bony lesion if pt is < 30 yoa
Differential for a lesion with a bony sequestrum
Osteoid Osteoma
Giant Cell Tumor
unable to tell benign or malignant on xray
Occurs only in pts with closed epiphyses
Must be epiphyseal and abut the articular surface
well defined non-sclerotic margin
4 Giant Cell Tumor Rules
Occurs only in pts with closed epiphyses
Must be epiphyseal and abut the articular surface
well defined non-sclerotic margin
Rules do not apply to flat bones.
NOF (non-ossifying fibroma
Fibrous Cortical Defect (< 2cm)
well defined lytic minimally expansile assymptomatic,< 30 yoa, cortically based.
don't touch lesion
mention when ABC esp in the post elements of the spine
Metastatic Disease
consider for any lytic lesion in anybody > 40 yoa.
a metastatic lesion can appear benign
bubbly lytic lesions of multiple myeloma
In general lytic expansile lesions tend to come from?
The only metastatic lesion that is always lytic?
Aneurysmal bone cyst
<30 yoa
often occur in posterior spine
Solitary Bone Cysts
Fallen fragment sign pathognomonic
prox long bones
< 30 yoa
no periostitis
Hyperparathyroid (Brown tumors)
subperiosteal bone resorption mc in radial aspect of middle phalanges
<30 yoa
Differential Dx of an epiphyseal lytic lesion in a pt < 30 yoa
Giant cell tumor
Subchondral Cyst or Geode occurs in what 4 diseases
Chondromyxoid Fibroma
mention with NOF
no calcified matrix
Lesions in pts younger than 30
Solitary bone cyst
Lesions without pain or periostitis
Solitary bone cyst
Bony lesion to always mention?
<30 yoa
infection, EG
>40 yoa
infection, mets, mm
Epiphyseal DDX
infection, Gaint cell tumor, Chondroblastoma, Geode
The only lesion that must have a calcified matrix?
(except in the phalanges)
4 indicators of a bony lesion that determine malignancy?
What is the most useful indicator?
cortical destruction
orientation/axis (not very helpful)
zone of transition (most useful)
2 benign lesions that may look malignant
Benign periostitis has what type of characteristics
Malignant periostitis has what type of characteristics
Name a lesion that grows in the long axis of the bone, but is very malignant
Ewing Sarcoma
What is a permeative lesion
a lesion consisting of many small holes
2 childhood primary malignant bone tumors
Ewings Sarcoma
Malignant bone tumors after 40 yoa
Where do paraosteal osteosarcomas originate from
periosteum of the bone and grows outside. It often wraps around the diaphysis without breaking the cortex. if it breaks the cortexit is considered agressive and has a worse prognosis
What benign lesions can mimic a paraosteal osteosarcom?
Cortical Desmoid Tumor
Myositis Ossificans
What is a cortical Desmoid Tumor
An avulsion injury that is entirely benign, but looks agressive
What is the differential for a bony permeative lesion in a child
Chondrosarcoma rarely occurs in children, but it can occur when what type of tumor degenerates
What percent of Giant Cell tumors metastasize? Where do they metastasize to?
What 3 bony tumors can have a bony sequestrum
Malignant Fibrous Histiocytoma
Desmoid tumor
What is the only malignant bone tumor that can involve a large amount of bone eventhough the pt is assymptomatic
Reticulum Cell Sarcoma
(primary Bone Lymphoma)
What is one of the only bony lesions that is not hot on a bone scan
What are the 2 MC soft tissue tumors
Malignant Fibrous Histiocytoma
a break or defect in the pars interarticularis of the lamina
Kummel Disease
occurs 1 to 2 weeks after initial trauma. a wedge compression fx further collapse
What disease always requires increased imaging in trauma?
Ankylosing spondylitis
Failure to treat a lunate dislocation will effect which nerve?
peri-lunate dislocation
* lunate remains aligned with radius
* capitate dislocates (usually posteriorly)

* more common than lunate dislocation (radial-lunate ligaments stronger than lunate-capitate ligaments)

* associated with scaphoid fractures (75%) = "transscaphoid perilunate dislocation"
lunate dislocation
* lunate dislocates posteriorly
* other carpal bones remain in alignment

less common than perilunate dislocation
Kienbock Malacia
* lunate AVN
* associated with ulnar minus variance
A small chip of bone off the dorsum of the wrist is which bone
Colles FX
* radial fracture in distal 2 cm
* +/- ulnar styloid fracture
* dorsal displacement of distal fragment
* "silver-fork" deformity

* most common fracture in this region
* mechanism: fall on an outstretched hand
* complication: post-traumatic arthritis
Smith FX
fx distal radius ("reverse Colles")
volar angulation of distal fragment
Barton FX
intra-articular fracture of distal radius

* dorsal displacement of separated fragment
* due to fall on outstretched hand
Chaffeur's FX
radial styloid fracture due to direct blow

* (so named because of trauma from hand-cranked starters)
Monteggia FX
angulated fracture at the junction of the proximal and middle third of ulna accompained by ANTERIOR dislocation of the radial head


* transmission of force thorugh the hand and forearm with the elbow partially flexed
* interosseous ligament "drags" the radius with the distal two-thirds of the ulna

# MUGR mnemonic

* Monteggia with ulna (proximal)
* Galeazzi with radius (distal)
Galeazzi FX
radial fx
dislocated distal ulna

* mnemonic: "MUGR" (Monteggia ulna, Galeazzi radius)
* Monteggia More common
What are the 3 hallmarks of DJD?
Joint space narrowing
Bohler Angle
< 20 degrees indicates a calcaneal fx
aka: alkaptonuria

* autosomal recessive
* excessive homogentisic acid
o no homogentisic acid oxidase
o part of phenylalanine / tyrosine pathway

* alkaptonuria: brown/black urine
* ochronosis: brown/black pigmentation of skin, mucous membranes

* pigment deposition in articular cartilage of joints
o ==> chronic arthritis (usually evident in 4th decade)
* narrowed, calcified intervertebral disks

* renal calculi
* nephrocalcinosis
manifestations can occur singly or in any combination

* pseudogout
o acute crystal-induced synovitis with clinical symptoms analogous to gout

* arthropathy
o beaklike osteophytes of 2nd, 3rd metacarpal heads
o subchondral cysts (esp. carpal bones)
o unusual distribution of disease (radiocarpal/ulnar joint, patellofemoral joint)
o SLAC - scapholunate advanced collapse

* chondrocalcinosis
o triangular fibrocartilage
o symphysis pubis
o menisci of knee
o annulus fibrosus of intervertebral disk
Name 3 diseases with high association with CPPD
T or F, No malignant tumors arise from joints
Pigmented Villonodular Synovitis
* monoarthritis
* young adults
* benign neoplasm affecting extremity joints

* subchondral erosions on BOTH sides of joint (!)
* hemosiderin deposited in synovium (with characteristic low signal on MR)
* articular cartilage preserved (despite extensive marginal erosions; similar to gout)
* NO calcification, but soft tissue may appear dense on X-ray/CT


* TB (associated atrophy of muscle + bone)
* rheumatoid arthritis (symmetrical)
* synovial sarcoma (+/- calcified; outside joint)
* synovial osteochondromatosis
Sudeck Atrophy
Sudeck dystrophy, causalgia, shoulder-hand syndrome, post-traumatic osteoporosis

* pain, tenderness, soft tissue swelling out of proportion to injury
* vasomotor instability (Raynaud, vasoconstriction/-dilation)
* end stage (6-12 months): contractures, atrophy (skin and soft tissues)
* location: hands and feet distal to injury


* injury (fracture, frost bite; may be trivial)
* immobilization
* infection
* myocardial infarction


* periarticular soft tissue swelling
* patchy dimineralization
* increased uptake (periarticular) on bone scan
* perfusion and blood pool phases not sensitive
Which fat pad gets displaced with a hip joint effusion
Obturator Internus
Causes of AVN?
Etiology ("PLASTIC RAGS"):

idiopathic, infection
caisson disease, collagen vascular disease

radiation, rheumatoid arthritis
Gaucher disease
sickle cell disease


* sclerosis
* crescent sign
* collapse (e.g., of femoral head)
AVN Staging
Stage CT/xray bone scan
----- ------- ---------

I - cold/hot spot

II sclerotic focus with
osteopenic ring

III "crescent sign"
(subchondral lucency)

IV articular collapse
flattening of femoral head

sensitivity 86% 78%
specificity 79% 75%
What is the earliest sign of AVN
Kohler Disease
osteochondrosis of tarsal navicular
degeneration followed by reossification of one or more ossification centers in children

* Legg-Calve-Perthes disease (capital femoral epiphysis)
* Kohler disease (tarsal navicular)
* Osgood-Schlatter disease (tibial tuberosity)
* Scheuermann disease (vertebral ring epiphyses)
* Freiberg infraction (metatarsal head)
* Sever disease (apophysis of os calcis)
* osteochondritis dissecans

All osteochondrosis have a low signal on T1
Osteochondritis Dissecans
subchondral fatigue fracture commonly seen in adolescents

1. capitellum of elbow
2. knee
* medial femoral condyle close to fossa intercondylaris
* bilateral in 20-30%, rarely lateral
3. talus

* mouse = osteochondrotic fragment
* mouse bed = sclerosed pit in articular surface
MC site for Osteochondritis Dissecans
Knee (medial epicondyle), Talus(dome)
Magic angle phenomenon
# Increased signal intensity may be present on the upward sloping portion of the PCL on short TE images, mimicking a tear. It is present in anatomic components of the ligament oriented 55° to the main static magnetic field, along the long axis of the magnetic bore.

# The phenomenon can be distinguished from a true PCL tear using long TE-weighted imaging sequences. When using proton-density imaging, the artifact may persist if the TE is 20 milliseconds or less.

# If the abnormal signal focus persists, a true PCL abnormality is present. Artifacts from MAP disappear when long TE sequences are used
Myositis Ossificans
circumferential calcification with a lucent center
Cortical desmoid
a process on the medial supracondylar ridge of the distal femur that is considered by many to be the result of an avulsion of the adductor magnus muscle
Where do cortical desmoids occur?
posteromedial epicondyle of the femur
Discogenic Vertebral Sclerosis
always adjacent to the endplate, and the associated disk space should be narrow
cortical defect of the patella
lytic defect in the upper outer quadrant. normal variant
pseudocyst of the humerus
another entity that is often mistaken for a lytic pathologic lesion. an anatomic variant caused by increased
cancellous bone in the region of the greater tuberosity of the humerus, giving this region a more lucent appearance on radiographs (11,12). With hyperemia and disuse caused by rotator cuff problems or any other shoulder disorder, this area of lucency may appear strikingly more lucent and mimic a lytic lesion
Os odontoideum
normal variant of the cervical spine that may, in fact, be posttraumatic . It is an unfused dens that may move anterior to the C2 body with flexion and can mimic a fractured dens . Many of these require surgical fixation; some surgeons fuse every case, believing that they are all unstable
Nonossifying fibroma (NOF)
NOF is identical to a fibrous cortical defect, but the term is usually reserved for defects larger than 2 cm. They are, classically, lytic lesions located in the cortex of the metaphysis of a long bone and have a well-defined, often sclerotic, scalloped border with slight cortical expansion . They are found almost exclusively in patients younger than the age of 30 years; hence, the natural history of the lesion is involution. As they involute, they fill in with new bone, giving it a sclerotic appearance (Fig. 46.20) thus, they can have some increased radionuclide activity on bone scans. They are most often mistaken for an area of infection, eosinophilic granuloma, fibrous dysplasia, or aneurysmal bone cyst. They are asymptomatic.
Bone islands
mimic sclerotic metastases always asymptomatic
two signs can be found to help distinguish giant bone islands from metastases.
First, bone islands usually are oblong, with their long axis in the axis of stress on the bone: for example, in a long bone they align themselves along the axis of the diaphysis. Second, the margins of a bone island, when examined closely, will show bony trabeculae extending from the lesion into the normal bone in a spiculated fashion (15). This is characteristic of a bone island and helpful in differentiating it from a more aggressive process.
Unicameral bone cysts
often prophylactically curettaged and packed so as to prevent fracture with subsequent deformity. When these cysts occur in the calcaneus, however, they should be left alone. They always occur in the anteroinferior portion of the calcaneus

area that does not receive undue stress. In fact, a pseudotumor of the calcaneus is seen in the identical position because of the absence of stress and resulting atrophy of bony trabeculae (Fig. 46.24). These lesions are asymptomatic, only rarely fracture, and should not suffer the same fate as their counterparts in long bones—that is, surgical removal
Bone Infarction
Early in the course of its development, a bone infarct can have a patchy or mixed lytic-sclerotic pattern or even resemble a permeative process
most common type of short limbed dwarfism; caused by defect in enchondral bone formation => shortening of tubular bones with normal shaft caliber

* hereditary: auto-dominant, > 90% sporadic

x-ray features:

* short extremities and ribs v. trunk length
* "ball-in-socket" epiphyses
* pelvis: squared iliac wings and narrow sacrosciatic notch ("champagne glass")
* hands: fingers widely opposed and equal length ("trident hands")
* skull: enlarged vault and mandible, small f. magnum
* spine:
o narrow AP diameter with concave posterior surface and spinal canal only 1/2 normal depth
o decreased lumbar interpediculate distance
o hypoplastic ("bullet nose") T-L vertebrae
spine typically has narrowing of the interpedicular distances in a caudal direction (Fig. 47.1), the opposite of normal, in which the interpedicular distances get progressively wider as one proceeds down the spine. The long bones are short but have normal width, giving them a thick appearance
Common Causes of Avascular Necrosis
Collagen vascular diseases
Alcoholism, aspirin
Idiopathic causes
Common Radiographic findings of AVN
patchy sclerosis
articular surface collapse
serpiginous borders
subchondral lucency
periosteal reaction
in adults:

* hypertrophic osteoarthropathy (HOA)
* pachydermoperiostosis
* vascular insufficiency
* thyroid acropachy
* fluorosis

in kids:

* physiologic periostosis
* Caffey disease
* acute leukemia
* scurvy
* rickets
* congenital syphilis
* hypervitaminosis A
hypertrophic osteoarthropathy
* pulmonary
* malignancy (bronchogenic Ca, lymphoma, mets)
* abscess
* COPD / bronchiectasis

* pleural
* pleural fibroma (highest incidence of HOA, tho' rare itself)
* mesothelioma

* cardiac
* cyanotic congenital heart dz

* GI
* inflammatory dz (Crohn, UC)
* malabsorption (dysentery, lue, cirrhosis)

* ** causes symmetrical periosteal reaction
rare condition of cortical thickening of unknown etiology most commonly seen in the long bones

* 3-59 years

* sx: usu. pain of varying severity, occ. limited ROM, contracture

* insidious onset and chronic course

xray findings:

* cortical sclerosis and thickening that may encroach on the medullary canal -- looks like wax flowing down a candle
abnormal elaboration + storage of mucopolysaccharides

* autosomal recessive (except Hunter [type II], X-linked recessive)


* "dysostosis multiplex" (wide medial clavicle, flat ribs, etc.)
* short stature
* hepatosplenomegaly
* coarse facies, ocular disease


Hurler / Scheie
All mucopolysaccharidoses are AR except which one
Hurler's syndrome
mucopolysaccharidosis (MPS) type I (aka: gargoylism)

* autosomal recessive deficiency of X-L iduronidase
* 1 in 10000 births
* prognosis: death in early teens

* dwarfism
* mental retardation
* kyphosis
* long bones are short and thick
* phalanges of hands: coarse texture, wide shafts, tapered proximal ends (esp. metacarpals)
* hepatosplenomegaly
* thick everted lips, large tongue, small malformed teeth
* J-shaped sella
buildup of heparan sulfate
Morquio's disease
mucopolysaccharidosis (MPS) type IV

* autosomal recessive deficiency of N-acetylgalactosamine-6-sulfatase
build up of keratin sulfate

* normal intelligence
* platyspondyly ("universal vertebra plana" = hallmark)
* dwarfism, kyphosis, severe disability
* anterior beaks of vertebrae/bullet shaped
* "wine glass" pelvis
what is a characteristic finding in all of the mucopolysaccharidoses on bone films?
notch at the base of the fifth metacarpal
osteochondroma (exostosis)
* age: 10 - 30 yrs

* bony outgrowth
* points away from joint
* site: metaphysis; long bones
o 50% at knee or shoulder

* generally benign
o calcified cartilagenous cap ==> premalignant
o may --> chondrosarcoma

* familial type of multiple osteochondromatoses
==> increased risk of malignancy
* M > F, 35 - 50 yrs
* malignant, poor prognosis
* tx: removal, RT

* sites: metaphysis, center of flat bones
o pelvis, ribs, upper femur, shoulder
* slow growing
* large soft-tissue mass +/- flocculent calcifications
* sclerosis

* may arise from pre-existing "benign" enchondroma or osteochondroma
hereditary exostosis (osteochondromatosis)
* autosomal dominant
* M > F

* multiple exostoses
* "snowflake" calcification of mature cartilage cap
* may --> chondrosarcoma

* short metacarpals (esp. 4th + 5th)
widened diameter of the bone, often seen in hereditary exostosis
osteoid osteoma
* M:F 2:1, 5 - 25 y/o (90%) (50% 10-20)
* pain at night - prostaglandin E2
* pain responds to salicylates
* tx: surgical excision of nidus, rare spontaneous regression

* location
o metadiaphysis and metaphysis of long bones(73%)
o spine (14%)
o hands and feet (12%)

* lucent nidus with thickened cortex on CT and plain film
* Perinidal bone marrow edema and soft tissue inflamation on MRI

* DDx:
o Brodie abscess
o Ewing sarcoma
o osteosarcoma
o sclerosing osteomyelitis
Brodie abscess
subacute osteomyelitis

* distal end of long bones
* well-defined, lytic
* +/- sclerotic rim

* tx: open abscess, curette, pack with bone chips
* prognosis: excellent after tx


* osteoid osteoma
* EG
Ewing sarcoma
small, round-cell sarcoma of mesenchyme of medullary bone

* age 5 - 14 yrs
* most lethal of all 1' bone tumors

* any bone
o < 20 y/o: long bones
o > 20 y/o: flat bones (where there's still red marrow)

* purely lytic (62%), purely sclerotic (15%)
* periosteal reaction (onion-skin or perpendicular)

* similar lesion at different age
o < 5 y/o -- neuroblastoma
o > 30 y/o -- mets, reticulum cell sarcoma
How can u distinguish between an Osteoid Osteoma and Osteomyelitis?
because the nidus is extremely vascular, it avidly accumulates radiopharmaceutical bone-scanning agents. An osteoid osteoma will have an area of increased uptake corresponding to the area of reactive sclerosis and will additionally demonstrate a second area of increased uptake corresponding to the nidus (Fig. 47.13). This has been termed the double-density sign (4). In contrast, osteomyelitis has a photopenic area corresponding to the plain film lucency that represents an avascular focus of purulent material. The natural history of an osteoid osteoma is presumed to be spontaneous regression, as they are rarely seen in patients over the age of 30
Osteopathia Striata
Voorhoeve disease,
2- to 3-mm-thick linear bands of sclerotic bone aligned parallel to the long axis of a bone (Fig. 47.14).
affects multiple long bones asymptomatic
incidental finding
rare, autosomal dominant bone disorder

* multiple, small, circumscribed round or ovoid areas of increased bone density, widely distributed, caused by condensations of the spongiosa

* NO symptoms

associated with:

* dermatofibrosis lenticularis disseminata
* scleroderma
* syndactyly
* dwarfism
* endocrine abnormalities
* melorrheostosis
* cleft palate
mistaken for diffuse osteoblastic disease
incidental finding


"idiopathic, familial hypertrophic osteoarthropathy"

* boys at puberty
* blacks > whites
* familial

* periosteal reaction
o proximal phalanges, distal long bones of legs and forearms
o cortical thickening without medullary narrowing
* thick skin: extremities + forehead
* hyperhidrosis
* relatively pain free
Transient osteoporosis of the hip can look like?
Chondromalacia patellae
most commonly occurs in young adults, is a syndrome of crepitus and pain at the anterior knee associated with cartilaginous changes along the undersurface of the patella
Classification system for Monteggia fracture-dislocations.

* Type I - Fracture of the middle or proximal third of the ulna and anterior dislocation of the radial head (65%).
* Type II - "reversed" Monteggia injury. Fracture of the middle or proximal third of the ulna and posterior dislocation of the radial head (18%).
* Type III - Ulnar fracture distal to the coronoid process with lateral radial head dislocation (16%).
* Type IV - Fracture of the proximal or middle third of the ulna with an anterior dislocation of the radial head and fracture of the proximal third of the radius (rare).
Hill-Sachs deformity
indentation or groove on posterolateral aspect of humeral head

* probably d/t compression of humeral head on posterior lip of glenoid
* may occur after one episode of shoulder dislocation

a/w: Bankart lesion of glenoid
Bankart deformity
* osteochondral fracture of inferior glenoid labrum
* a/w anterior shoulder dislocation

see also: Hill-Sachs deformity
WHat us Kummell's Disease?
delayed post traumatic vertebral body collapse which may follow minimal trauma. May be a subtype of AVN.
Segond Fx
a/w acl tear
avulsion of the lateral capsular ligament
Wimberger’s sign
localized bony destruction of the medial portion of the proximal tibial metaphysis
a/w congenital syphillis
Saber Shin
Congenital Syphillis
Malgaigne fracture
two vertical fractures involving one side of the pelvic ring

* one fracture anterior to the acetabulum
o usually through the pubic ramus

* one fracture posterior to the acetabulum
o usually through the ilium
o separation of the SI joint may occur instead

usually the result of direct trauma
Segond FX
avulsion fx px lateral tibia at lateral capsular ligament insertion

avulsion px fibula
biceps femoris
lateral collateral ligament
Little Leaguer's elbow
avulsion fx of MEDIAL epicondyle
Panner's Disease
AVN Capitellum
Complications of MHE
Multiple Hereditary Exostosis
Vascular injury
Neurologic compromise
Bursa formation
Malignant transformation
cancers that tend to calcify
mucinous adenocarcinoma
what are the overuse syndromes of the patella?
The overuse syndromes of the patellar tendon include Osgood-Schlatter disease, Sinding-Larsen-Johansson syndrome, and Jumper’s knee.
Defint the 3 overuse syndromes of the patella
Osgood-Schlatter disease, which involves the tibial tubercle, and Sinding-Larsen-Johansson syndrome, which involves the inferior pole of the patella. Jumper’s knee is a chronic tendinitis that affects the patellar tendon at its proximal insertion.
associates of patella alta include?
Quadriceps tendon atrophy
Cerebral palsy
Sinding-Larsen-Johansson syndrome
what are the findings in sinding-larsen-johansson syndrome
Patellar fragmentation, edema anterior to the Hoffa’s fat pad, and proximal patellar tendinosis with thickening and edema are all characteristic findings of Sinding-Larsen-Johansson syndrome. Displacement of the distal patellar pole is unusual.
what is the difference between patella sleeve avulsion fracture and Sinding-Larsen-Johansson syndrome?
Patellar sleeve avulsion fracture involves a cartilaginous injury to the inferior pole of the patella. MRI is usually necessary to differentiate from Sinding-Larsen-Johansson syndrome which has similar radiographic findings but represents a pure osseous injury with no cartilage involvement. Distinguishing between these entities is very important for patient management. Minimally or nondisplaced fractures seen with Sinding-Larsen-Johansson syndrome are often managed conservatively, whereas displaced patellar sleeve avulsion fractures usually require open reduction with or without internal fixation and extensor mechanism reconstruction. Osgood-Schlatter disease has the same etiology and presents in a similar population as Sinding-Larsen-Johansson syndrome; however, the process involves the tibial tuberosity.
mc complication from acl repair
Patella baja is one of the most common postoperative complications of anterior cruciate ligament repair.
mc benign bone tumor
Milwaukee Shoulder
Complete Rotator Cuff Tear
Effusion with CPPD
Synovial Hyperplasia
Cartilage Destruction
Osteochondral loose bodies
Early OsteoArthritis
Epiphyseal Dysplasia
3 Types of Osteoid Osteomas
Cortical (=nidus in cortex): has solid/laminated periosteal reaction radiolucent center (nidus) ± central osteosclerosis
Cancellous (=intramedullary): intraarticular lesion, difficult to identify; little osteosclerosis; widened joint space
Subperiosteal (rare): round soft-tissue mass adjacent to bone
most common cause of protrusio acetabuli
Segond Fracture
represents an avulsion of the lateral capsular ligament. It occurs posterior to Gerdy’s tubercle
a/w ACL tear in 75-100%,
a/w meniscal tear in 67%!
Terrible Triad of O’donoghue
ACL Injury
Medial collateral ligament
Medial meniscus
DDX Ivory Vertebral Body

Sickle cell disease,
Trauma/Tuberculous spondylitis,
Renal osteodystrophy,
Osteoblastic metastasis,
Chronic sclerosing osteomyelitis / chordoma, Hemangioma,
Paget’s disease
Diffuse Idiopathic Skeletal Hyperostosis
Normal mineralization,
flowing ossification of at least four contiguous vertebral bodies,
preservation of disc spaces,
ossification of multiple tendinous and ligamentous sites in the appendicular skeleton,
absence of joint abnormalities,
sporadic distribution
primarily in the spine
Tumoral Calcinosis
large soft tissue calcifications,
separate from the bone,
overlying multiple joints.
Note that many of these lesions are clearly extra-articular, which excludes synovial osteochondromatosis
Key finding on the upright film is that of a fluid-fluid level, which clinches the diagnosis.
Uptake on a bone scan is common in this condition
DDX Dense Bones
“Regular Sex Makes Occasional Perversions Much More Pleasurable And Fantastic”
Renal Osteodystrophy,
Sickle Cell,
Paget’s Dz,
How to tell apart the causes of increased bone density:
Hyperparathyroidism = renal cause
Small spleen = sickle cell disease
Big spleen = mastocytosis or myelofibrosis
Bone within bone = osteopetrosis
Acro-osteolysis = pyknodysostosis
Mixed with destruction = metastases
Expanded bone = Paget’s
DDX Acro-osteolysis
Thrombangitis obliterans,
Ergot therapy,
Dilantin Rx,
Injury (e.g., thermal),
Arteriosclerosis obliterans,
PVC worker,
Rheumatoid arthritis,
Leprosy, Lesch-Nyhan,
Absence of pain,
CREST syndrome:
Calcinosis of skin,
Esophageal dysmotility, Sclerodactyly
Dense Metaphyseal Bands
D-vitamin intoxication,
Elemental arsenic & heavy metals,
Normal variant,
Systemic illness,
Estrogen to mother during pregnancy,
Leukemia, Infection (TORCH),
Never forget healed rickets,
Early hypothyroidism,
congenital Syphilis,
Sickle Cell Disease
Signs of a ligamentum teres tear
thickening or thinning of the ligament,
intrasubstance signal abnormality

What labs are elevated in dermatomyositis?

Aldolase, transaminases, CPK, and LDH

What are the three primary stabilizers of the Posterolateral Corner in the knee?

The three primary stabilizers are the popliteofibular ligament,

fibular collateral ligament,

the popliteus tendon.

What lesions may be a/w secondary ABC (Aneurysmal Bone Cysts)?




CT findings in Necrotizing Fasciitis?

The CT findings of subcutaneous emphysema, multispace involvement, soft-tissue pockets of fluid, and marked asymmetric soft-tissue edema are most consistent with necrotizing fasciitis.

Predisposing factors for necrotizing fasciitis?


diabetes mellitus,


minor trauma,

male gender,

advanced age,

intravenous drug abuse,

prolonged hospitalization,

and indwelling catheters.

MCC necrotizing fasciitis?

Necrotizing fasciitis is most commonly polymicrobial involving



Escherichia coli,


and/or Enterobacteriaceae

Which muscles reside in the deep and superficial posterior compartments of the leg?

  • The superficial muscles of the posterior compartment include the gastrocnemius, plantaris, and soleus. The deep muscles of the posterior compartment include the popliteus, tibialis posterior, flexor digitorum longus, and flexor hallucis longus.

MC Meniscal Tear

The posterior horn of the medial meniscus is the most common site of meniscal tears.