Limits of the Musculoskeletal System (Week 4)

Question 1

state what it is meant by the key term - ‘injury prevention’

Answer 1

injury prevention is the process of minimising the risk factors in order to reduce the likelihood of injury

Question 2

what is the 4 step sequence of injury prevention outlined by (van Mechelen et al., 1992)

Answer 2

1. establishing the extent of the injury problem
2. establishing the causes and mechanisms of sports injuries
3. introducing a preventative measure
4. assessing its effectiveness by repeating step 1

Question 3

when will injury occur

Answer 3

when the loads placed on the MS system in an event is greater than the mechanical limits of the structures of the MS system

Question 4

state the 2 mechanical roles of the skeletal system

Answer 4

structural and protective

Question 5

state the 2 physiological roles of the skeletal system

Answer 5

Ca2+ regulation and blood cell production in the bone marrow

Question 6

state 2 facts about the organic component of bones

Answer 6

1) cells (osteoblasts, osteoclasts, osteocytes, and cell lining)
2) matrix (mostly type 1 collagen) - gives bone its flexibility

Question 7

state 2 facts about the inorganic component of bone

Answer 7

1) mineral content (hydroxyapatite) makes bone stronger

2) hydroxyapatite - a complex salt of calcium and phosphate

Question 8

state the 2 types of bone

Answer 8

1) cortical/compact bone

2) cancellous/spongy/trabecular bone

Question 9

state 3 facts abbot cortical/compact bones

Answer 9

1) 80% of bone mass
2) situated on the external surfaces of bones (walls of diaphysis)
3) principally have a mechanical function

Question 10

state 5 facts about cancellous/trabecular/spongy bone

Answer 10

1) 20% of bone mass
2) lattice of fine plates
3) situated in the epiphysis of long bones, vertebral bodies, and flat bones
4) spaces filled with bone marrow
5) reduces skeletal mass without compromising skeletal strength

Question 11

state what it is meant by he key term - ‘material properties’

Answer 11

properties of the material itself, regardless of the specimen (i.e. - stress at which a sample of cortical bone breaks under compression)

Question 12

state the two ‘material properties of bone’

Answer 12

1) bone density

2) compression strength of bone

Question 13

state what it is meant by the key term - ‘structural properties’

Answer 13

• properties of a specific specimen
• i.e. - breaking stress for tibia
• more difficult to define

Question 14

what are the two types of bone growth ?

Answer 14

1) Longitudinal growth

2) circumferential/radial growth

Question 15

state 4 facts about longitudinal bone growth

Answer 15

1) endochondral ossification
2) primary ossification centre
3) secondary ossification cente (epiphyseal plates)
4) ceases when secondary growth plates fuse during adulthood (forms the epiphyseal line)

Question 16

state 2 facts about circumferential/radial growth

Answer 16

1) diameter of bone increases throughout an individual’s lifespan
2) is rapid before adulthood, and is then very slow during adulthood

Question 17

state what it is meant by the key term - ‘periosteum’

Answer 17

a layered covered membrane covering bone; muscle tendons attach to the outer layer, and the internal layer isn the site of osteoblast activity

Question 18

what is the role of the periosteum during bone growth

Answer 18

the internal layer of the periosteum builds concentric layers of bone on too of existing bone. at the same time, bone is reabsorbed or eliminated around the circumference of the medullary cavity, so the cavity is continuously enlarged

Question 19

state what it is meant by the key time - ‘bone remodelling’

Answer 19

the process by which bone mass is maintained, increased, or decreased

Question 20

state what it is meant by the key term - ‘Wolf’s Law’

Answer 20

bone elements place, or displace, themselves in the direction of functional forces, and increase or decrease their mass to reflect the amount of functional forces (the bone will adapt to the loads placed upon it)

Question 21

where is the sensory feedback of bone micro-damage ?

Answer 21

• sensory feedback from micro damage in bone

- initiates the bone remodelling response involving osteoclasts (bone resorption) and osteoblasts (bone formation)

Question 22

state what it is meant by the key term - ‘functional adaptation’

Answer 22

the bone adapts to the loads placed upon it

Question 23

what is required to maintain bone mass ?

Answer 23

external loads are required to maintain bone mass

Question 24

state 3 points about ‘Bone Atrophy’

Answer 24

• inactivity - bone mass and micro content decreases
• predominance of osteoclast activity
• e.g. - bed rest of space flight

Question 25

state 3 facts about 'Bone Hypertrophy'

Answer 25

- increase in activity - bone mass increases due to the predominance of osteoblast activity - e.g. - greater bone mass in dominant arm of racket sports - trabecular alignment can change to adapt to a new load (Pontzer et al., 2006)

Question 26

state what it is meant by the key term - 'functional adaptation'

Answer 26

the bone adapts to the loads placed upon it

Question 27

when should bone not fail /

Answer 27

bone should not fail under 'normal' circumstances

Question 28

why does a bone fracture occur?

Answer 28

a bone fracture occurs if the stress on the bone exceeds the strength of the material

Question 29

state 3 causes of a bone fracture

Answer 29

1) excessive force 2) weak material (e.g. - osteoporosis) 3) cumulative damage due to repetitive loading

Question 30

what determines the type of bone fracture?

Answer 30

velocity and the type of impact will determine the type of bone fracture

Question 31

state what it is meant by the key term - 'complete fracture'

Answer 31

the break goes all the way through the bone, separating it into two

Question 32

state what it is meant by the key term - 'incomplete fracture'

Answer 32

your bone does not completely break all the way through

Question 33

state what it is meant by the key term - 'transverse fracture'

Answer 33

when the fracture line is perpendicular to the shaft (long part of the bone)

Question 34

state what it is meant by the key term - 'oblique fracture'

Answer 34

when the break is at an angle through the bone

Question 35

state what it is meant by the key term - 'spiral fracture'

Answer 35

when the bone is broken via a twisting action

Question 36

state what it is meant by the key term - 'comminuted fracture'

Answer 36

where the bone is broken into more than 2 pieces

Question 37

state what it is meant by the key term - 'avulsed fracture'

Answer 37

when a small chunk of bone attached to a tendon or ligament gets pulled away from the main part of the bone

Question 38

state what it is meant by the key term - 'impacted fracture'

Answer 38

when a bone fractures, a piece of that bone may impact another bone. this occurs when a break extends into the surface of a joint

Question 39

state what it is meant by the key term - 'torus/buckle fracture'

Answer 39

one side of the bone bends, raising a little buckle, without breaking the other side of the bone

Question 40

state what it is meant by the key term - 'greenstick fracture'

Answer 40

where one side of the bone is broken, and the other side of the bone becomes bent

Question 41

state what it is meant by the key term - 'compression fracture'

Answer 41

caused by pressure and causes the bone to collapse

Question 42

state what it is meant by the key term - 'segmental fracture'

Answer 42

fractures where at least two fracture lines create a separate cylindrical intermediate segment

Question 43

state 4 facts about 'plain x-rays'

Answer 43

- 2D radiographic imaging - required manoeuvring of patient - simple, available, affordable - low radiation dose

Question 44

state 4 facts about 'computerised tomography (CT)'

Answer 44

- 3D radiographic imaging - very high resolution of bone, and some soft tissue - moderately expensive - high radiation dose, 200x that of a chest x-ray

Question 45

state 3 facts about bone repair

Answer 45

- haematoma (a severe bruise) leads to clot formation - cartilage fills the gap(s) which is ossified to form a new woven bone (callous) - a bit like scar tissue - callous then remodels over time into cortical and compact bone

Question 46

what is the repair time of bones?

Answer 46

uptown 6 weeks for upper limbs and 12 weeks for lower limbs (faster for both in children)

Question 47

state 2 additional facts about bone repair

Answer 47

- CAN be as strong/stronger than the bone before the break | - formation of callous bone is very quick

Question 48

state what it is meant by the key term - 'osteoporosis'

Answer 48

a condition lacking the nutrition and hormonal input to maintain bone mass over time

Question 49

why is osteoporosis more common in women ?

Answer 49

reduction in oestrogen in post-menopausal women - disrupts the remodelling process

Question 50

what is the effect of reduced oestrogen on osteoporosis?

Answer 50

- leads to a reduction in trabecular bone | - reduction in bone mineral density (BMD) and increases the risk of a fracture

Question 51

what can be used to diagnose BMD?

Answer 51

'Duel Energy X'Ray Absorptiometry' (DEXA scan)

Question 52

state 2 other causes of osteoporosis

Answer 52

- poor nutrition | - greater osteoclast than osteoblast activity

Question 53

when do stress fractures occur ?

Answer 53

occur when the remodelling process cannot keep up with the damage occurring to the bone

Question 54

what is stress fracture occurrence dependent upon?

Answer 54

dependent upon the magnitude of load and the number of load cycles

Question 55

where are stress fractures most common ?

Answer 55

- metatarsals | - tibia

Question 56

how can stress fractures be identified ?

Answer 56

x-rays

Question 57

explain how a 'Bone Scan' (a form of nuclear medicine) works

Answer 57

1) patient injected with radioactive marker (Technetium 99 bound to disphosphate - gamma radiation) 2) bisphosphate is used to up regulate osteoblast activity in areas needed to be treated 3) low spatial resolution but high sensitivity 4) usually followed by more specific imaging 5) available in most hospitals but moderately expensive 6) high (ish) radiation dose

Question 58

state 2 bone conditions in developing people

Answer 58

1. Osgood Schlatter's disease | 2. Sever's disease

Question 59

state 4 facts about 'Osgoof Schlatter's disease' and 'Sever's disease'

Answer 59

- most common in 10-15 year olds - running and jumping sports - repetitive tension on rapidly changing changing growth plates - self-limiting conditions (resolves at the end of a growth spurt)