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skeletal system (Bone Tumors (Tumor–like lesion (simple bone cyst:
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skeletal system
Bone Tumors
- Tumor-like lesions
- Primary bone tumors – bone, cartilage forming: benign, malignant
- Secondary bone tumors - metastases
- Incidental tumors without clinical significance („don`t touch me lesions”)
bone islands, haemangiomas (98%), defectus fibrosus (nonossifying fibroma)
Tumor–like lesion
- simple bone cyst:
unknown etiology,
occurence – the first two decades of life,
location - proximal metaphysis of humerus and femur bone,
well defined radiolucent lesion
Aneurysmal bone cyst
- benign lesion, 90% in patients under 20 years old, de novo or in a preexisting lesion, X-ray multiloculated cyst with fluid – fluid levels
Haemangioma
- incidentaloma, benign tumor, 98% non significant, Rarly symptomatic or agressive
Osteoid osteoma
- Benign osteoblastic lesion, Age 10-35y M, 75% - pain more severe at night, dramatically relieved by aspirin, Location long bones (femur , tibia), X-ray – a nidus of osteoid tissue surrounded by osteosclerosis
Enchondroma
- Age 15-40, M=F, Site: Phalanges and metacarpals of hands, X-ray –radiolucent expanding lesion with calcifications, Multiple echondroma enchondromatosis (Ollier disease)
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Osteosarcoma
- second most common bone’s malignant neoplasm
- Age: 10-25y, second peak – old age, M:F=2:1
- Secondary osteosarcoma – in Paget`s disease or after radiotherapy
- In 25% cases of osteosrcoma coexisting metastases (often bone forming)
- Site - metaphysis or diaphysis in 50-75%, distal femur, proximal tibia, humerus, pelvis, any bone
- X-ray: ** lytic or sclerotic form, periosteal reaction (spiculation, Codman tirangle [osteosarcoma,
Ewing’s sarcoma, subperiosteal abscess]), destruction of cortex, invasion of adjacent soft tissues,“Sunburst”, “hair on end”**
- Diagnosis –X-ray, CT and mainly MRI
Ewing sarcoma
- Age: 2-30y, M>F,
- site – young patients – diaphysis of long bones, over 20y – flat bones (pelvis, scapula, ribs),
- X-ray: ill defined area of bone destruction, lamellated periosteal reaction “Onion skinning”
- Symptoms and X-ray appearance may mimic osteomyelitis,
pain, swelling, fever
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Metastases to bone
- The most common neoplasm of bone
- Age > 45y
- Site: vertebrae,pelvis, skull, ribs, long bones
- X-ray : osteolytic, osteosclerotic or mixed
- Osteo-lytic (decreased density) bone metastases: lung ca, renal ca, breast ca, thyroid ca, stomach ca, colon ca, Multiple myeloma
- Osteo-sclerotic (Sclerotic = increased density) metastases
In men: prostate ca, seminoma, Lung, neurogenic tumours, carcinoid, osteosarcoma
In women: breast ca, uterus ca, ovarium ca, carcinoid, osteosarcoma
- age – most common tumours by age group:
<1 yr of age: metastatic neuroblastoma
1-20 yr of age: Ewing’s sarcoma in tubular bones
10-30 yr of age: osteosarcoma and Ewing’s tumour in flat bones
more than 40 yr of age: metastases, multiple myeloma, and chondrosarcoma
- location within bone:
epiphysis: giant cell tumour, chondroblastoma, geode, eosinophilic granuloma, infection
metaphysis: simple bone cyst, aneurysmal bone cyst, enchondroma, chondromyxoid fibroma, nonossifying fibroma, osteosarcoma, chondrosarcoma
diaphysis: fibrous dysplasia, aneurysmal bone cyst, brown tumours, eosinophilic granuloma, Ewing’s sarcoma
fractures
types
- simple - bone breaks into two pieces
- complete or incomplete
- impacted fracture - one fragment of bone is embedded into another
- comminuted fracture - bone fragments into several pieces
- avulsion fracture – a pull-off fracture
- greenstick fracture
- stress fracture
- pathological fracture
Avulsion fractures
- a pull-off fracture at a musculotendinous or ligamentous insertion caused by sudden forceful muscle contraction or ligament traction
- bone fragment pulled from
the parent bone by a tendon or ligament as a result of physical trauma.
- Young people, Sport activities
Greenstick fracture
- in children, under 13, when the bone does not completely break through
- one side of a bone is broken while the other bent
- torus fracture – specific type of greenstick fracture in which the bone is compressed to form a ring (called torus)
Special types
- fatigue fractures – abnormal stress - normal bone (stress)
- insufficiency fractures – abnormal bone under normal stress (stress + pathologic)
- pathologic - abnormal bone under normal or subnormal force ( pathologic)
Fatigue fractures
- Caused by repetitive long lasting strain during submaximal activity, repeated microstress overwhelms the bone ability to adapt
- Related to sports or occupational activity
- Metatarsal shaft (march fracture), tibial shaft, calcaneal tuberosity, fibula
- X –ray: fracture fissure may not be demonstrated, but usually there is abundant callus/periosteal proliferation.
- Differential diagnosis – tumour, osteomyelitis
- No dislocation, Pain relief at rest
Pathological fractures
- occur in: tumour-like lesions (cysts), primary bone tumours, metastases, osteoporosis
Vertebral fractures
- Flexion – often with posterior ligamentous disruption and anterior subluxation- cervical spine:
simple wedge fracture, flexion teardrop fracture
- Extension mechanism – occurs when the anterior longitudinal ligament is disrupted:
hangman fracture, extension teardrop fracture
- Rotary – unilateral facet joint dislocation, pedicles are broken
- Vertical –compression – often burst fracture of the vertebral body and anterior and posterior vertebral arches:
Jefferson fracture (C1)
Fracture complications
- injury of major blood vessels and nerves
- Sudeck atrophy (reflex sympathetic dystrophy syndrome = post-traumatic painful osteoporosis) affects hand or foot – neurotrophic abnormality: swelling, pain, dystrophic skin changes – X-ray- progressing patchy osteoporosis
- delayed union (refers to a fracture that does not unite within a reasonable time -16-18 weeks)
- growth disturbances
- nonunion with osteomyelitis
- bone necrosis (ischaemic = avascular necrosis)
- pseudoarthorsis - (formation of false joint, often occur in the tibia)
- posttraumatic ossification (myositis ossificans)
- posttraumatic degenerative changes
- Pseudoarthrosis - false bone healing:
caused by the failure of bones to fuse
lack of callus
formation of false joint cavity
sclerotic margins
Avascular bone necrosis
- causes: trauma, diabetes, Cushing syndrome, steroid, radiotherapy, alcohol abuse, hyperlipidemia, neuropathic arthrit., osteomyelitis
- Most common location: femoral head, metatarsal head, tarsal bones, carpal bones, medial condyle of the femur, vertebral bodies
- ischemic necrosis causing mechanical failure of the bone
- MRI is capable of detecting the early stage before the bone collapse and fragmentation (decompression of the joint)
- diffuse edema low T1, increased T2 early phase
- focal serpiginous low signal line
- double-line sign
- focal subchondral low signal lesion on T1 with variable signal on T2
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Normal bone healing
- undisplaced, anatomically reduced
and adequatly immobilized fractures heal by primary union
- periosteal and endosteal callus formation
In infants- after 1 week
In children - after more than 1 week
In adults – after 3-4 weeks
- callus formation takes 3 - 8 months
- fracture fissure may be visible even a year after trauma (in skull bones-after several yrs)
- clinical union occurs earlier than radiographic union
modality
- First choice imaging method is conventional radiography
- Ultrasound is very usefully method for joint assessment
- best imaging modality for musculoskeletal assessment is MRI
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Football knee injury
- MRI: O`Donaghue triad: MCL and ACL rupture, lateral meniscus bucket handle tear, bone bruise
Menisci
- normal –sagittal slice has bowtie shape and homogenous signal
- meniscus tear- abnormal high signal lesion which disrupts the articular surface of a meniscus
- bucket-handle tear-when the inner edge of the meniscus displaces – absent bowtie sign –a displaced meniscal fragment can be found in the intercondylar notch
Tendons
- normal-relatively avascular structures that attach muscles to bones.
- normal- low signal intensity on all sequences
- high signal intensity occurs in degeneration, partial and complete tear
- partial tear–incomplete disruption of the fibres; thickened, thinned or normal
- complete tear – absence of the tendon continuity; two separate fragments
- tenosynovitis- fluid surround the tendon involving tendon sheath, focal high signal in tendon
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Diabetic foot
- Abnormal bone marrow signal:low signal T1 and high signal T2 with fat sat
- Cutaneous ulcer overlying the bone abnormality
- Cortical destruction
- Intramedullary abscess
- Absence of bone marrow changes on STIR images excludes the diagnosis of osteomyelitis.
Spondylodiscitis
- disc space narrowing, destruction of vertebrae end plates, paravertebral, epidural abscesses
- Classic MRI Triad:
T1low signal vertebral body marrow
T1, post contrast; marrow enhancement( and possible disk)
T2: high signal in disk(and possible marrow)
- Associated abnormalities:
decrease disk height
destruction of endplates
phlegmon or abscess, epidural, subligamentous, paraspinous
Brodie abscess
- chronic inflammation, affects young people, occurs in the tibial metaphysis, (MRI & CT)
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