Ch 4-5 Flashcards
2 highly specialized connective tissues the skeletal system is composed primarily of
Bone
Cartilage
Consists of an organic matrix in which organic salts (primarily calcium and phosphate) are deposited
Bone
Fibrous membrane that covers the outer surfaces of bone, except at joint surfaces, where articular cartilage covers the bone and acts a protective cushion
Contains a network of blood vessels from which nutrient arteries penetrate into the underlying bone
Periosteum
Main shaftlike portion of bone
Diaphysis
Ends of the bone
Epiphysis
Hollow, tubelike structure within the diaphysis
Medullary cavity/marrow
Inner membrane that lines the medullary cavity
Endosteum
2 major types of bone
Compact
Cancellous
Outer layer of bone
Compact bone
Spongy inner layer of bone composed of a web-like arrangement of marrow-filled spaces
Cancellous (spongy) bone
Thin processes of bone that separate the spaces of cancellous bone
Trabeculae
Until the linear growth of bone is complete, the epiphysis remains separated from the diaphysis by a cartilaginous plate
Epiphyseal cartilage
Where the diaphysis meets the epiphyseal growth plate is a slight flaring
Metaphysis
2 special types of bone cells
Osteoblasts
Osteoclasts
Enlarge the diameter of the medullary cavity by removing bone from the diaphysis wall
Osteoclasts
Produce new bone around the outer circumference
Osteoblasts
Bone formation
Ossification
Bone destruction
Resorption
Connective tissue membrane bones can also develop within
Intramembranous ossification
Flat bones grow in size by the addition of osseous tissue to their outer surfaces
Appositional growth
Spinal canal defect caused from failure of the posterior elements to fuse properly
Spina bifida
Large defects of spina bifida have 2 complications of hernias
Meningocele
Myelomeningocele
Herniation of the meninges
Meningocele
Herniation of the meninges and a portion of the spinal cord or nerve roots
Myelomeningocele
3 malformations associated with a meningocele
Gait disturbances
Clubfoot
Bladder incontinence
Rare hereditary bone dysplasia in which failure of the resorptive mechanism of calcified cartilage interferes with the normal replacement by mature bone
Results in very brittle bones
Location: entire skeleton
Imaging appearance: generalized increased bone density
Osteopetrosis
“Marble bones”
An inherited generalized disorder of connective tissue characterized by multiple fractures and an unusual blue color of the normally white sclera of the eye
Osteogenesis imperfecta (OI) "Brittle bone disease"
Most common form of dwarfism
Results from diminished proliferation of cartilage in the growth plate (decreased enchondral bone formation)
Autosomal dominant condition
Characterized by short limbs with a normal axial skeleton
Thick bones
Location: vertebrae (short stature), long bones
Imaging appearance: progressive interpedicular distance from superior to inferior, and scalloping of posterior vertebral bodies; widened metaphysis (Erlenmeyer flask deformity)
Achondroplasia
Results from incomplete acetabulum formation caused by physiologic and mechanical factors
Congenital hip dysplasia/dislocation
Developmental hip dysplasia
9 inflammatory and infectious disorders
Rheumatoid arthritis Osteoarthritis (degenerative joint disease) Infectious arthritis Tuberculous arthritis Bursitis Rotator cuff tears Tears of the menisci of the knee Bacterial osteomyelitis Tuberculous osteomyelitis
Chronic systemic idiopathic disease that appears primarily as a noninfectious inflammatory arthritis of the small joints of the hands and feet
Location: small joints symmetrically
Imaging appearance: periarticular soft tissue swelling and symmetric joint destruction and deformity
Rheumatoid arthritis (RA)
3 rheumatoid arthritis (RA) variants
Ankylosing spondylitis
Reiter’s syndrome
Psoriatic arthritis
Very common generalized disorder characterized by loss of joint cartilage and reactive bone formation
Part of the wear and tear of the aging process
Affects the weight-bearing joints (spine, hip, knee, ankle) and the interphalangeal joints of the fingers
Imaging appearance: irregular narrowing of joint space with small bony spurs
Osteoarthritis (degenerative joint disease)
Chronic, indolent infection that has a gradual onset and a slowly progressive course
Most patients have pulmonary TB
Rare
Tuberculous arthritis
3 joints usually involved in tuberculous arthritis
Spine
Hips
Knees
An inflammation of the small fluid-filled sacs located near the joints that reduce the friction caused by movement
Location: shoulder most common
Imaging appearance: calcific tendinitis in 50%
Bursitis
The rotator cuff of the shoulder is a musculotedinous structure composed of the teres minor, infraspinatus, supraspinatus, and subscapularis muscles
Tears produce a communication between the shoulder joint and the subacromial bursa
MRI is the modality of choice, inject contrast (arthrogram) before
Rotator cuff tears
5 causes of bursitis
Repeated physical activity (most common) Trauma Rheumatoid arthritis Gout Infections
2 causes of tears of the menisci of the knee
Acute trauma
Degeneration due to chronic trauma
Common cause of knee pain, MRI is the modality of choice
Tears of the menisci of the knee
An inflammation of the bone and marrow caused by a variety of infectious organisms that reach bone by hematogenous spread, extension from an adjacent site of infection, or direct introduction of organisms (after trauma or surgery)
In infants and kids, the metaphysis of long bones (high in red marrow), especially the femur and tibia, are most often affected
In adults, acute hematogenous primarily occurs in the vertebrae, causing localized back pain and muscle spasms
Begins as an abscess of the bone; pus produced by the acute inflammation spreads down the medullary cavity and out to the surface
Imaging appearance: soft tissue swelling with periosteal elevation
Bacterial osteomyelitis
Rare osteomyelitis today that usually affects the T and L spine
Location: vertebra
Imaging appearance: lytic lesion without periosteal elevation and collapsed vertebra with kyphosis
Tuberculous osteomyelitis (Pott’s disease)
2 types of osteomyelitis
Bacterial osteomyelitis Tuberculous osteomyelitis (Pott's disease)
5 metabolic bone diseases
Osteoporosis
Osteomalacia
Rickets
Gout
A generalized or localized deficiency of bone matrix in which the mass of bone per unit volume is decreased in amount but normal in composition
Causes include aging and postmenopausal hormonal changes, more common in females
Location: loss of bone mass in entire skeleton (accelerated bone resorption)
Imaging appearance: cortical thinning appears as a relatively dense and prominent thin line
Osteoporosis
A ________ in kVp is required to obtain quality images of a patient with osteoporosis
Decrease
Insufficient mineralization of the adult skeleton
May be caused by inadequate intake or absorption of calcium, phosphorus, or vitamin D
Other nutritional causes are chronic kidney failure or kidney diseases that cause calcium secretion in the urine
Softening of the bone
Location: deossification of medullary bone
Imaging appearance: loss of bone density and cortex becomes thin and often indistinct
Osteomalacia
Systemic disease of infancy and childhood that is the equivalent of osteomalacia in adults
Calcification of growing skeletal elements is defective because of a deficiency of vitamin D in the diet or a lack of exposure to ultraviolet radiation (sunshine) which converts sterols in the skin into vitamin D
Soft bones
Location: insufficient mineralization of the immature skeleton
Imaging appearance: cupped and frayed metaphysis in long bone
Rickets
A disorder in the metabolism of purine (a component of nucleic acids)
Increases uric acid in the blood, which leads to the deposition of uric acid crystals in the joints, cartilage, and kidney
Manifests as very painful arthritis that initially attacks a single joint, primarily the first metatarsophalangeal joint
Additive and destructive
“Rate bite” erosions
If you have a mass forming, calcium will get into it and show up on x-rays
Location: 1st MTP joint but may attack any joint
Imaging appearance: joint inflammation (effusion) and destruction and/or uric crystals (tophi) in joint space
Gout
One of the most common chronic metabolic diseases of the skeleton
Associated increased risk of osteosarcoma
No known cure
Bone destroys itself, then comes back thicker; painful
Middle-age +
Most common in pelvis, seen well in skull
Can go into other areas of the bone
Location: destruction and reparative process in pelvis, weight-bearing bones, and skull
Imaging appearance: radiolucencies in destructive (lytic) phase and cotton-wool appearance in reparative phase
Paget’s disease
Osteitis deformans
Results from the ingestion of lead-containing materials (especially paint) or from the occupational inhalation of lead fumes
Environmental exposure occurs when drinking water (leaded pipes) and eating food that’s processed, preserved, or stored in containers made with lead
Currently lead is the number one major environmental pollutant worldwide
Chronic form may cause mental retardation, seizures, behavioral disorders, or delayed development
Children are more susceptible to lower doses (eat lead containing paint = pica)
In kids, because lead and calcium are used interchangeably by bone, high concentrations of lead are deposited in the most rapidly growing portions of the skeleton, especially the metaphysis at the distal ends of the femur
Lead poisoning
Characterized by the proliferation of fibrous tissue within the medullary cavity that causes loss of trabecular markings and widening of the bone
Fibrous dysplasia
Occurs due to a loss of blood supply with many different causes
Ischemic necrosis of bone
8 benign bone tumors
Osteochondroma Enchodroma Giant cell tumor (osteoclastoma) Osteoma Osteoid osteoma Simple bone cyst Aneurysmal bone cyst Bone island
5 malignant bone tumors
Osteogenic sarcoma Chondrosarcoma Ewing's sarcoma Multiple myeloma Bone metastases
Benign projection of bone with a cartilaginous cap that arises in childhood or teen years, commonly near the knee
Location: epiphyseal plate growing laterally in long bones
Imaging appearance: tumor runs parallel to long bone and points away from nearest joint
Osteochondroma
2 characteristics of osteochondromas
Long axis of tumor runs parallel to the bone shaft
Points away from the nearest joint
Slow-growing benign cartilaginous tumors arising in the medullary canal
Primarily in the small bones of the hands and feet
Often found when a fracture occurs with minimal force
Most frequent in kids and young adults and primarily involve the small bones of the hands and feet
Enchondroma
Typically arises at the end of the distal femur or proximal tibia of a young adult after epiphyseal closure (20-40 years old)
Does not affect the joint
Location: metaphysis extends into subarticular cortex
Imaging appearance: multiple large bubbles separated by strips of bone
Giant cell tumor (osteoclastoma)
Most often arise in the outer table of the skull, the paranasal sinuses (especially frontal and ethmoid) and the mandible
Cause pain
Appear radiographically as well-circumscribed, extremely dense, round lesions that are rarely larger than 2 cm in diameter
Osteoma
Typically imaged as a small, round or oval, lucent center (the nidus), less than 1 cm in diameter, that is surrounded by a large, dense sclerotic zone of cortical thickening
It is most common in teenagers or young adults.
Symptom is local pain, which increases at night and is easily relieved by aspirin
Location: femur and tibia, osteoblastic cells
Osteoid osteoma
A true fluid-filled cyst with a wall of fibrous tissue, which most often occurs in the proximal humerus or femur at the metaphysis
Asymptomatic and often discovered either incidentally or after pathologic fracture
Simple bone cyst
Not a true neoplasm or cyst
Consists of numerous blood-filled, arteriovenous communications thought to be caused by trauma
Aneurysmal bone cyst
Solitary, sharply demarcated areas of dense compact bone that occur most commonly in the pelvis and upper femur
Appear in every bone except the skull
Bone island
Generally occurs in the end of a long bone in the metaphysis (especially about the knee)
A malignant tumor of osteoblasts, which produce osteoid and spicules of calcified bone
Most common in persons between 10 and 25 years old
Smaller peak incidence is seen in older persons who have a preexisting bone disorder, particularly Paget’s disease
Metastases to the lungs
Mixed destructive and sclerotic lesion associated with a soft tissue mass
Imaging appearance: “sunburst” pattern or Codman’s triangle
Osteogenic sarcoma
A malignant tumor of cartilaginous origin that may originate anew or within a preexisting cartilaginous lesion, e.g., osteochondroma and enchondroma
Commonly occurs in long bones, but often originates in a rib, scapula, or vertebra
About half as common as osteogenic sarcoma
It develops at a later age (peak incidence in 35- to 60-year olds), grows more slowly, and metastasizes later
Chondrosarcoma
A primary malignant tumor arising in the bone marrow of long bones
Occurs in children and young adults and is rare over age 30
Destructive (takes away calcium) to whole area of bone
Major clinical complaint is local pain
Imaging appearance: medullary destruction with “onionskin” periosteal reaction
Ewing’s sarcoma
A widespread malignancy of plasma cells associated with bone destruction, bone marrow failure, hypercalcemia, renal failure, and recurrent infections
Affects primarily persons between 40 and 70 years of age
Eats away at the bone
Location: intramedullary canal of the diaphysis
Imaging appearance: multiple punched-out lesions
Multiple myeloma
The most common malignant bone tumors that are more common than primary neoplasms
They spread from primary tumors by means of the bloodstream or lymphatic vessels or by direct extension
The most common primary tumors are carcinomas of the breast, lung, prostate, kidney, and thyroid.
Favorite sites of spread are bones containing red marrow, such as the spine, pelvis, ribs, skull, and the upper ends of the humerus and femur
Location: entire skeleton
Imaging appearance: irregular, poorly defined lucent lesions or poorly defined increased densities depending on site of origin
Bone metastases
Metastases from carcinomas of the kidney and thyroid typically produce a single large metastaic focus that may appear as an expansive trabuculated lesion
“Blowout”
In the spine, bone metastases may produce a characteristic uniform density
“Ivory” vertebral body
Generally considered evidence of slow growth in a neoplasm that has allowed time for a proliferation of reactive bone (additive)
Osteoblastic metastases
A disruption of bone caused by mechanical forces applies either directly to the bone or transmitted along the shaft of a bone
Although often obvious, some are subtle and difficult to detect
Typically appears as a radiolucent line crossing the bone and disrupting the cortical margins
Fracture
4 ways fractures are defined and classified
Extent
Direction and position
Number of fracture lines
Integrity of the overlying skin
Fracture that results in discontinuity between two or more bone fragments
Complete fracture
Fracture that causes only partial discontinuity, with one side of bone cortex intact
Incomplete fracture
Fracture with overlying skin intact
Closed fracture
Fracture with associated skin wound, overlying skin is disrupted
Open/compound fracture
Fracture line is horizontal/runs at a right angle to long axis of bone
Most commonly results from a direct blow or is a fracture within pathologic bone
Transverse fracture
Fracture line extends at approximately a 45 degree angle to long axis of bone and is caused by angulation or by both angulation and compression forces
Oblique fracture
Fracture line encircles the shaft, is generally longer than an oblique fracture, and is caused by torsional forces
Spiral fracture
Small fragments torn from bony prominences by being pulled from bone by attached ligaments or tendons
Avulsion fractures
Fracture composed of more than two bone fragments
Comminuted fracture