Limits of the Musculoskeletal System (Week 4) Flashcards
state what it is meant by the key term - ‘injury prevention’
injury prevention is the process of minimising the risk factors in order to reduce the likelihood of injury
what is the 4 step sequence of injury prevention outlined by (van Mechelen et al., 1992)
- establishing the extent of the injury problem
- establishing the causes and mechanisms of sports injuries
- introducing a preventative measure
- assessing its effectiveness by repeating step 1
when will injury occur
when the loads placed on the MS system in an event is greater than the mechanical limits of the structures of the MS system
state the 2 mechanical roles of the skeletal system
structural and protective
state the 2 physiological roles of the skeletal system
Ca2+ regulation and blood cell production in the bone marrow
state 2 facts about the organic component of bones
1) cells (osteoblasts, osteoclasts, osteocytes, and cell lining)
2) matrix (mostly type 1 collagen) - gives bone its flexibility
state 2 facts about the inorganic component of bone
1) mineral content (hydroxyapatite) makes bone stronger
2) hydroxyapatite - a complex salt of calcium and phosphate
state the 2 types of bone
1) cortical/compact bone
2) cancellous/spongy/trabecular bone
state 3 facts abbot cortical/compact bones
1) 80% of bone mass
2) situated on the external surfaces of bones (walls of diaphysis)
3) principally have a mechanical function
state 5 facts about cancellous/trabecular/spongy bone
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
state what it is meant by he key term - ‘material properties’
properties of the material itself, regardless of the specimen (i.e. - stress at which a sample of cortical bone breaks under compression)
state the two ‘material properties of bone’
1) bone density
2) compression strength of bone
state what it is meant by the key term - ‘structural properties’
- properties of a specific specimen
- i.e. - breaking stress for tibia
- more difficult to define
what are the two types of bone growth ?
1) Longitudinal growth
2) circumferential/radial growth
state 4 facts about longitudinal bone growth
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)
state 2 facts about circumferential/radial growth
1) diameter of bone increases throughout an individual’s lifespan
2) is rapid before adulthood, and is then very slow during adulthood
state what it is meant by the key term - ‘periosteum’
a layered covered membrane covering bone; muscle tendons attach to the outer layer, and the internal layer isn the site of osteoblast activity
what is the role of the periosteum during bone growth
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
state what it is meant by the key time - ‘bone remodelling’
the process by which bone mass is maintained, increased, or decreased
state what it is meant by the key term - ‘Wolf’s Law’
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)
where is the sensory feedback of bone micro-damage ?
- sensory feedback from micro damage in bone
- initiates the bone remodelling response involving osteoclasts (bone resorption) and osteoblasts (bone formation)
state what it is meant by the key term - ‘functional adaptation’
the bone adapts to the loads placed upon it
what is required to maintain bone mass ?
external loads are required to maintain bone mass
state 3 points about ‘Bone Atrophy’
- inactivity - bone mass and micro content decreases
- predominance of osteoclast activity
- e.g. - bed rest of space flight
state 3 facts about ‘Bone Hypertrophy’
- 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)
state what it is meant by the key term - ‘functional adaptation’
the bone adapts to the loads placed upon it
when should bone not fail /
bone should not fail under ‘normal’ circumstances
why does a bone fracture occur?
a bone fracture occurs if the stress on the bone exceeds the strength of the material
state 3 causes of a bone fracture
1) excessive force
2) weak material (e.g. - osteoporosis)
3) cumulative damage due to repetitive loading
what determines the type of bone fracture?
velocity and the type of impact will determine the type of bone fracture
state what it is meant by the key term - ‘complete fracture’
the break goes all the way through the bone, separating it into two
state what it is meant by the key term - ‘incomplete fracture’
your bone does not completely break all the way through
state what it is meant by the key term - ‘transverse fracture’
when the fracture line is perpendicular to the shaft (long part of the bone)
state what it is meant by the key term - ‘oblique fracture’
when the break is at an angle through the bone
state what it is meant by the key term - ‘spiral fracture’
when the bone is broken via a twisting action
state what it is meant by the key term - ‘comminuted fracture’
where the bone is broken into more than 2 pieces
state what it is meant by the key term - ‘avulsed fracture’
when a small chunk of bone attached to a tendon or ligament gets pulled away from the main part of the bone
state what it is meant by the key term - ‘impacted fracture’
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
state what it is meant by the key term - ‘torus/buckle fracture’
one side of the bone bends, raising a little buckle, without breaking the other side of the bone
state what it is meant by the key term - ‘greenstick fracture’
where one side of the bone is broken, and the other side of the bone becomes bent
state what it is meant by the key term - ‘compression fracture’
caused by pressure and causes the bone to collapse
state what it is meant by the key term - ‘segmental fracture’
fractures where at least two fracture lines create a separate cylindrical intermediate segment
state 4 facts about ‘plain x-rays’
- 2D radiographic imaging
- required manoeuvring of patient
- simple, available, affordable
- low radiation dose
state 4 facts about ‘computerised tomography (CT)’
- 3D radiographic imaging
- very high resolution of bone, and some soft tissue
- moderately expensive
- high radiation dose, 200x that of a chest x-ray
state 3 facts about bone repair
- 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
what is the repair time of bones?
uptown 6 weeks for upper limbs and 12 weeks for lower limbs (faster for both in children)
state 2 additional facts about bone repair
- CAN be as strong/stronger than the bone before the break
- formation of callous bone is very quick
state what it is meant by the key term - ‘osteoporosis’
a condition lacking the nutrition and hormonal input to maintain bone mass over time
why is osteoporosis more common in women ?
reduction in oestrogen in post-menopausal women - disrupts the remodelling process
what is the effect of reduced oestrogen on osteoporosis?
- leads to a reduction in trabecular bone
- reduction in bone mineral density (BMD) and increases the risk of a fracture
what can be used to diagnose BMD?
‘Duel Energy X’Ray Absorptiometry’ (DEXA scan)
state 2 other causes of osteoporosis
- poor nutrition
- greater osteoclast than osteoblast activity
when do stress fractures occur ?
occur when the remodelling process cannot keep up with the damage occurring to the bone
what is stress fracture occurrence dependent upon?
dependent upon the magnitude of load and the number of load cycles
where are stress fractures most common ?
- metatarsals
- tibia
how can stress fractures be identified ?
x-rays
explain how a ‘Bone Scan’ (a form of nuclear medicine) works
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
state 2 bone conditions in developing people
- Osgood Schlatter’s disease
2. Sever’s disease
state 4 facts about ‘Osgoof Schlatter’s disease’ and ‘Sever’s disease’
- 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)
