Connective Tissue Flashcards
What is produced by osteoblasts that inhibits RANK / RANKL interaction?
Osteoprotegerin
What are two types / patterns of bone and what forces do they resist?
Cortical / compact: outer shell of bone. Resists bending
Cancellous / spongy bone: inner trabecular bone. Resists compression. more metabolically active.
2 types of bone formation
Intramembranous: flat bones: mesenchyme -> osteoprogenitor -> osteoblast
Endochondrial: long bones: cartilage model -> perichondrium -> bone collar -> primary ossification center
3 joint types
Diarthrodial (synovial)
Amphiarthrodial (cartilaginous): intervertebral disc
Synarthroses (fibrous): skull sutures
How do red and yellow bone marrow appear on MRI?
On T1 weighted image:
Red marrow is gray
Yellow marrow is white
Is osteoporosis an issue of quality or quantity of bone?
Quantity
Existing bone is qualitatively normal
5 disease states that can -> osteoporosis
Hyperparathyroidism Hyperthyroidism Cushing's Diabetes Acromegaly
In osteopenia, what is the relationship of cortical bone to total bone diameter?
Normally cortical bone constitutes 50% or more of the total bone diameter
In osteopenia, cortices thin, so ratio of cortical / medullary bone decreases.
What are radiologic features of degenerative joint disease (osteoarthritis)?
Loss of joint space (cartilaginous fibrillation and erosion) Bony eburnation (increased cellularity and vascularization of subchondral bone) Subchondral cysts (synovial fluid intrusion or bone contusion) Osteophytes (revascularization of remaining cartilage and capsular traction -> bone spurs)
What is a vacuum disc?
collection of gas within intervertebral disc space due to degeneration of disc material.
What is spondylolisthesis?
Subluxation forward displacement of a vertebra (usually 5th lumbar)
complication of DJD of the spine
What is Schmorl’s Node?
Vertical displacement of intervertebral disc material into adjacent vertebral body.
DJD complication
Usually benign, but may contribute to pain
What are enthesophytes?
Calcification of ligamantal attachment to bone
What are the stages of fracture repair?
- Procallus: inflammatory stage, lasts several days following fx. hemorrhage + necrosis -> inflammation + edema -> granulation + osteoprogenitor cells -> organizing hematoma
- Bony callus
- Remodelling
What are pathological features of osteomyelitis?
- Sequestrum: dead, necrotic bone - ID by empty lacunae
- Involucrum: formation of sheath of new bone around dead bone by osteoblasts in periosteum (seen w/ chronic osteomyelitis
What are some genetic factors in systmic sclerosis?
Anti-centromere Ab: CREST
Anti-topoisomerase I (scl-70): severe disease in blacks
TGF-B1 polymorphisms: pulmonary fibrosis
Fibrillin-1 polymorphisms: Chocktaw Native Americans
What is microchimerism?
Concept in pathogenesis of scleroderma
Mother and fetal cells pass bidirectionally through placenta and persist.
Later cells become activated -> GVHD type reaction -> systemic sclerosis
What are functions of the sacral nerves?
S1: ankle eversion
S2-4: bowel and bladder control
What are components of the intervertebral discs?
Annulus fibrosis: T1 collagen
Nucleus pulposis: GAGs and low T2 collagen, >85% water
What conditions predispose to alanto-axial instability?
Trisomy-21
Juvenile RA
What is Klippel-Feil syndrome?
Multiple fused cervical vertebrae due to failed segmentation of cervical somites.
Assoc. w/ other abnormalities: cardiac, renal, brain stem
What direction does the curve most often deviate in infantile idiopathic scoliosis?
To the left in pts. birth - 3yrs.
Associated with other defects (usually very sick patients): heart, renal, etc.
In older patients, left curving scoliosis requires MRI to seek other major congenital defects.
In idiopathic adolescent scoliosis, what degree requires treatment?
30: bracing, surgery depending on case
90 deg: heart and lung impairment
With what conditions are neuromuscular scoliosis associated?
Neuromuscular: Cerebral Palsy, Muscular Dystrophy
What is the most common cause of congenital scoliosis?
Unilateral unsegmented bar deformity: Unilateral failure of vertebral segmentation
What is Scheurmann’s disease?
Thoracic hyperkyphosis: >5deg wedging at 3 consecutive vertebrae
Idiopathic. Treated with bracing and/or surgery
What is the most common cause of back pain in children?
Spondylolysis: fatigue fracture of pars interarticularis
Seen in FB players, gymnasts
Usually at L5 - S1
What are the most common organisms in osteomyelitis in the following age groups:
Newborn, non-newborn - 4 yrs, >4 yrs
Newborn: GBS, Neisseria
non-newborn - 4 yrs: S. aureus, H. influenzae
>4 yrs: S. aureus, Pseudomonas if foot infection
What is the most frequent organism involved in osteomyelitis in children w/ sickle cell?
S. aureus most common
Salmonella is frequently associated
What is the most common joint affected in pediatric septic joint?
Hip
What is Legg-Calve-Perthe’s Disease?
Pediatric avascular necrosis of the hip
Due to early stenosis of ligamentum teres (umbilical vein), femoral circumflex aa. not ready to take over
Bilateral in 10-15%
Crescent sign on xray
What is slipped capital femoral epiphysis?
Occurs during growth spurt
Separation of epiphysis from metaphysis along growth plate
No gender correlation
Height, weight, race (black)
What is Pott Disease?
Tuberculous Osteomyelitis affecting vertebral bodies
Iliopsoas involvement
Back pain, fever, night sweats, weight loss
2 complications that can arise out of chronic tuberculous osteomyelitis
- Secondary (AA) Amyloidosis
2. Squamous cell carcinoma of a draining sinus tract
What is the genetic cause of achondroplasia?
FGF-3 receptor mutation -> arrested growth plate development
Usually sporadic, assoc. with advanced paternal age
Also AD inheritance
2 main genetic variants of osteopetrosis
AR: severe firn
AD: less severe, but more common
Cause of osteopetrosis
Defective osteoclasts - Carbonic anhydrase II mutation -> inability to acidify pits -> lack of resorption -> brittle, dense bone
What exam / lab findings are common in multiple myeloma?
blood smear: rouleaux formation
urine: bence jones proteinuria, nephrotic casts
Osteoma: benign or malignant? location? age?
Benign bone growth. usually noticed in children. flat bones, esp. skull. asymptomatic.
Symptoms of osteoid osteoma? who affected? benign / malig?
Presents in adolescents, m>f, with focal pain in a long bone that is worse at night and relieved with NSAIDs.
benign. radiolucent core of vascular immature woven bone w/ thickened reactive bone surrounding.
Excision is curative
What is osteochondroma?
May be sporadic or hereditary (AD and multiple)
Growth derived from growth plate w/ hyaline cartilage cap, usually grows from metaphysis of femur near knee.
Stops growing w/ growth plate fusion around puberty.
What is enchondroma?
Usually seen in small tubular bone of hand or foot
Intramedullary growth of benign hyaline cartilage
What is a fibrous cortical defect?
Benign growth of benign fibroblasts and macrophagesw/in metaphysis of long bone
Fibrous defect: small, regresses ; Non-ossifying fibroma: large, persists.
Thin cortex -> risk of fracture
What is fibrous dysplasia?
3 variants: monostotic, polyostotic w/o endocrine dysfunction, polyostotic w/ endocrine dysfunction
GNAS gene gof mutation
ground glass appearance. fibroblasts mixed w/ immmature bone
What is the most common non-hematopoietic bone malignancy?
Osteosarcoma
Common radiographic feature of osteosarcoma
Codman’s Triangle