Bone Histology and Disease Flashcards
(60 cards)
1
Q
Describe bone
A
- rigid & static for mechanical purposes
- some elasticity
- physiologically active Ca (bone stores 99% of the body’s calcium), P (phosphate), & hematopoeisis (makes blood cells/platelets)
2
Q
Parathyroid function
A
- secretes parathyroid hormone (PTH) which regulates calcium & phosphate levels & monitor & adjust blood levels accordingly
- PTH affects bone, kidney, & GI metabolism (increased or decreased Ca)
- usually 4 parathyroid glands
3
Q
Describe bone biochemistry
A
- bone tissue is composed of tiny crystals of (Ca & P) embedded in a collagen framework
- calcium crystals give bones their compressional strength, harness, & rigidity
- collagen fibers give them their relative capacity for flexibility & tensile strength
4
Q
What are the 3 types of bone cells
A
- Osteoblasts (build)
- Osteocytes (line the interior surface of the bone)
- Osteoclasts (break down)
5
Q
Difference between cortical (compact) bone and trabecular (spongy) bone
A
- Cortical/compact bone is solid & dense
- Trabecular/spongy bone is more porous & looks like a honeycomb
6
Q
Describe bone at the tissue level
A
- all bones are composed of interior trabecular bone surrounded by cortical bone
- vertebrae are mostly trabecular bone surrounded by a thin cortical shell
- long bones have relatively more cortical bone with areas of trabecular bone concentrated toward their ends
- skeletal mass is 80% cortical bone & 20% trabecular but volume-wise we have more trabecular bone
7
Q
Functions of the bone
A
- allow for mobility via joints
- resist &/or transfers mechanical stresses
- maintain Ca homeostasis
- production & storage for blood/immune system components
8
Q
Describe the structure of bone
A
- long bones are comprised of diaphysis (long tubular shaft), epiphysis (articulating surface), & metaphysis (the area that flares out)
- children have epiphyseal plates which are cartilaginous between epiphysis & metaphysis
- bones deform with stress (young” modulus; stress/strain curve)
- bones also remodel according to stress (Wolff’s law); high stress = bone gets reinforced & low stress = bone gets resorbed
9
Q
Define hematopoiesis
A
- the production of blood cells & platelets which occurs in the bone marrow
10
Q
Difference between parathormone and calcitonin
A
- Parathormone: release calcium from bone
- Calcitonin: bone uptake calcium
11
Q
Symptoms of bone & joint disease
A
- pain
- decreased mobility
- deformity
12
Q
Define osteoporosis
A
- bone mineral density 2.5 standard deviations below normal for age 30
- peak bone mass is at 30 years
13
Q
Causes of osteoporosis
A
- estrogen loss
- corticosteroids
- loss of weight bearing/bed rest
- hyperparathyroidism
- hyperthyroidism
- chronic renal failure
14
Q
Epidemiology for osteoporosis
A
- most common metabolic bone disease
- 10 million people in the US
- risk factors include: females, thinner, & asian/caucasian
15
Q
Pathogenesis for osteoporosis
A
- combination of increased bone reabsorption & decreased bone formation
- imbalance between osteoclastic & osteoblastic function
- greatest effect on trabecular bone (vertebrae) & metaphysis of long bones
16
Q
Relevant factors of osteoporosis
A
- hormones
- aging
- nutrition
- physical activity
- ethnicity
- heredity
- low body weight
- smoking
17
Q
Primary osteoporosis
A
- idiopathic (no known cause)
- post-menopausal
- senile
18
Q
Secondary (caused by something else) osteoporosis
A
- endocrine disorders
- malabsorption syndromes
- chronic renal failure
- rheumatoid arthritis
- loss of menses
19
Q
Clinical features of osteoporosis
A
- back pain
- postural changes
- loss of height
- fractures
20
Q
Management of osteoporosis
A
- fall prevention & other risk reduction strategies
- proper nutrition
- functional loading as tolerable
- screening high risk groups (BMD)
21
Q
If you were asked to design a community exercise program for women at high risk for osteoporosis, what would you include?
A
- resistance training (loading of the axial skeleton)
- postural training
- fall prevention
22
Q
Describe osteomalacia
A
- softening of bone
- in children it’s called Rickets
23
Q
Pathogenesis of osteomalacia
A
- inadequate mineralization of newly formed bone
24
Q
Risk factors for osteomalacia
A
- diet: little variety or certain dietary practices, low in milk products, low in phosphate, & low in vitamin D
- anti-seizure medications
- cancers
- environment (limited sunlight, smog)
- family Hx of vitamin D metabolism disorders
- renal/hepatic pathology
25
Clinical manifestations of osteomalacia
- diffuse aching
- fatigue
- weight loss
- proximal muscle weakness
- postural deformities
- bowing of tibia & femur
- osteopenia
- fractures
- neuropathies
26
What might you observe in a child being evaluated in physical therapy with the concurrent diagnosis of Rickets?
- long bone deformities
- complaints of pain
- possible Hx of fractures
- if asked about diet they may be malnourished
27
Describe a hemangioma of vertebrae
- most common benign spinal neoplasm
- women between 40-50
- thoracic & lumbar spine
28
Symptoms of hemangioma
- back pain
- radicular pain
- spinal cord compression
- compression fracture
29
Describe avascular necrosis
- death of bone tissue due to a lack of blood supply
- most often occurs at hip
30
Symptoms of avascular necrosis
- pain
- decreased ROM
- for femoral head, pain may radiate into groin
31
Risk factors for avascular necrosis
- trauma or dislocation
- long term steroid use
- alcohol
- chemotherapy
- kidney disease with dialysis
- sickle cell disease
32
Describe osteomyelitis
- infection of the bone (eg. staphylococcus)
33
Causes of osteomyelitis
- open injury to the bone ("exogenous osteomyelitis")
- bacteremia, sepsis, pre-existing infection ("hematogenous osteomyelitis)
- chronic open wound or soft tissue infection
34
Risk factors for osteomyelitis
- diabetes
- hemodialysis
- immunosuppression
- sickle cell disease
- intravenous drug abuse
- elderly
- renal/hepatic failure
- alcohol abuse
35
Symptoms for osteomyelitis
- pain/tenderness in the infected area (may be a late sign; no pain fibers in cancellous bone)
- swelling & erythema in the infected area
- fever
- nausea, secondarily from being ill with infection
- drainage of pus through the skin
36
Management of osteomyelitis
- prevention of infections
- screening
- diagnosis (often late due to lack of signs/symptoms &/or being mistaken for something else; need imaging & need to ID specific pathogen)
- treatment (immediate & aggressive treatment; high-dose antibiotics, possibly surgery)
37
Which direction does thoracic scoliosis and lumbar scoliosis commonly curve
- Thoracic: commonly curves to the right
- Lumbar: commonly curves to the left
38
Frontal/transverse coupled motion general rules
- Cervical spine (C2-T2): ipsilateral
- Thoracic spine (T3-T7): contralateral
- Lumbar spine (T8-S1) flexion: ipsilateral
- Lumbar spine (T8-S1) extension: contralateral
39
Describe scoliosis
- lateral curves in excess of 10 degrees or greater (from the Cobb angle)
- 60% idiopathic
- curvature usually reaches its max progression during the adolescent growth spurt
40
What are the 5 different types of scoliosis
- Congenital: they were born with it
- Idiopathic: occurs with no cause
- Neuromuscular: commonly in children with cerebral palsy
- Postural: functional, may be caused by pain, spasm, herniation, & can become structural over time
- Syndromic: marfan
41
Idiopathic scoliosis classification
James classification: patient's age when the scoliosis was first identified
- Infantile: <3 years
- Juvenile: 3-10 years
- Adolescent: 10-20 years (4% of children 9-14 year)
- Adult: 20+ years
42
Problems associated with severe scoliosis in the thoracic and lumbar spine
- Thoracic: volume of the chest can be reduced especially if curve is >60 degrees
- Lumbar: may push the contents of the abdomen against the chest & interfere indirectly with heart & lung function and alter sitting balance & posture
43
Treatment for scoliosis
- <25 degrees: no aggressive treatment
- 25-40 degrees: braces often used to slow progression (TLSO/thoracic-lumbar-sacral-orthosis brace, Milwaukee brace, Boston brace, Charleston bending brace, & Providence brace)
- Curves of 40 degrees or greater usually need surgery
44
Describe infantile scoliosis
- lateral curvature in the spine of >10 degrees
- usually develops <6 months age
- spine usually bends left
- girls with right-bending curve have worse prognosis
- likely have cardiopulmonary abnormalities
- higher incidence of plagiocephaly (a slight flattening of one side of the head) and developmental dysplasia of the hip (ipsilateral to direction of spinal curvature)
45
Casting for infantile scoliosis
- infants with moderate & severe curves have a greater chance of progressing
- serial casting up to 18 months
- change cast/brace every 6-12 weeks
- cast is made of plaster or fiberglass & is applied in the operating room under general anesthesia
46
Complication of scoliosis
- Thoracic insufficiency syndrome: inability of the chest to support normal breathing or lung growth
47
Describe kyphoscoliosis
- scoliosis + kyphosis
- Juvenile kyphosis: posterior convexity that measures a Cobb angle greater than 5 in 3 adjacent thoracic vertebrae
- Causes: trauma, tumor, infection (usually tuberculosis), osteoporosis, Scheuermann's disease (seems to have a familial component), or a congenital or developmental process
48
Describe scheuermann's vertebral osteochondrosis
- ossification & endochondral growth with pathologic changes to discs & vertebral body junctions
- damage to the cartilage plates & ring epiphysis = Schmorl's nodes
- increased wedging of bodies & progressive kyphosis
49
Describe Schmorl's nodes
- most commonly in the lower thoracic vertebrae
- can result from herniation & associated pressure onto vertebral body surface -> necrosis
- note the disc protrudes through the endplate
50
Describe the clinical presentation of an adolescent with osteochondrosis
- kyphosis
- abnormal growth/lack of growth
- wedging of vertebrae
51
Difference between displaced/angulated and non-displaced fractures
- Displaced/angulated: bone fragments have shifted out of position
- Non-displaced: fragments maintain pre-injury anatomic shape & position
52
Types of fractures
- Stress: accumulated over time related to overuse
- Pathological: the force it takes to break the bone in reduced by a disease
- Traumatic
53
Stages of healing for bone
- the healing response of bone is the complete regeneration of original structures
- healing of an acute fracture to long bone (compact) proceeds through the same phases of inflammation, repair, & remodeling
54
Describe hematoma formation for bone
- immediately after the injury, bleeding into the fracture site will form a hematoma
- the inflammatory phase starts hours later (may last several weeks)
55
Describe repair phase of bone
- soft callus, then hard callus
- cell proliferation: chondrocytes & osteoblasts deposit an organic matrix & hematoma is slowly absorbed
- after 2-3 weeks, hematoma replaced by soft callus
- fibrocartilage formation: pro callus differentiates into dense, fibrous, osteoid tissue & X rays show continued presence of rarefaction (thin or less dense bone)
- as repair continues, size of soft callus gradually decreases, giving way to lamellar bone that forms a hard callus & joins the broken bone ends
- union will normally occur 4-6 weeks (arm) or 8-12 weeks (leg) after fracture
56
Describe the remodeling phase of bone
- remodeling of the hard callus will return the fracture site to its original bony structure & appearance
- bone callous will continue to shrink & shape into original bony structure
57
Describe epiphyseal bone
- growth plate in children & adolescents
- is particularly susceptible to acute & chronic injuries
- bone that forms as a result of injury to the epiphysis may alter or stop overall bone growth (can result in deformities)
58
Factors that affect bone healing
- immobilization
- blood supply
- position
- location of fracture
- type & severity of fracture
59
Complications related to fractures
- delayed union (takes excessively long), nonunion (fails to heal), malunion (heals in a bad position)
- osteonecrosis
- vascular injury
- nerve injury
- intra-articular & peri-articular adhesions
- infection
60
Describe soft tissue injury
- concurrent injury
- secondary dysfunction: disuse, adhesions (articular, periarticular, and/or capsulitis), and shortening
