Case 9 - Extra and PBL

Question 1

what is runners knee

Answer 1

patellofemoral pain syndrome

Question 2

what causes a runner’s knee

Answer 2

a kneecap that is too high in the knee joint

weak thigh muscles

tight hamstrings

tight achilles tendons

poor foot support

walking or running with the feet rolling in while thigh muscles pull the kneecap outward

excessive training or overuse

injury

Question 3

what are the symptoms of runner’s knee q

Answer 3

pain in and aorta d the kneecap that happens when you are active or pain after sitting for a long time with the knees bent. this sometimes causes weakness.

rubbing, grinding or clicking sound of the kneecap that you hear when you bend and straighten the knee

kneecap that is tender to the touch

Question 4

how is runner’s knee diagnosed

Answer 4

health history and physical exam

X rays may be needed for evaluation of the knee

Question 5

how is runner’s knee treated

Answer 5

cold packs
elevating the leg
compression knee wrap
pain meds
stretching and strengthening exercises
arch support in shoes

Question 6

what is a nocebo

Answer 6

a detrimental effect on health produced by physiological or psychosomatic factors such as negative expeditions of treatment or prognosis

Question 7

what are the types of acetylcholine receptors at neuromuscular junction

Answer 7

nicotinic not muscarinic

Question 8

why are ligaments more likely to tear in women

Answer 8

because of oestrogen and relaxin

Question 9

what can happen in resistance training

Answer 9

muscle fibres can change from type 2a to type 2x

Question 10

when and why do stress fractures show up on X rays

Answer 10

2-3 weeks after due to callus formation

Question 11

why should you not take NSAIDs for fracture pain

Answer 11

as need inflammation to repair and for bone remodelling

Question 12

what does strain gauge do

Answer 12

converts the mechanical strain into an electrical distance change and act as mechanical electrical converters. as a result of this change in resistance, they generate a voltage change proportional to the strain

Question 13

atypical gait - v important

Answer 13

Question 14

what is Wolff’s law

Answer 14

Wolff’s Law states that bones will adapt to the degree of mechanical loading, such that an increase in loading will cause the architecture of the internal, spongy bone to strengthen, followed by the strengthening of the cortical layer.

Question 15

what are the muscles involved in patella femoral pain

Answer 15

vastus lateralis, whcih pulls your patella up and outwards, and the vastus medals oblique which is the only quadricep muscle that pulls your kneecap up and slightly in.

Question 16

what are the common reasons for weak vastus mescals oblique include

Answer 16

knee injury, post surgery swelling or disuse

Question 17

what cells are important in maintaining populations of osteoblasts and the repair of a fracture

Answer 17

osteoprogenitor cells

Question 18

where are osteoprogenitor cells located

Answer 18

in the periosteum and bone marrow (endosteunm)

Question 19

what do osteoblasts form

Answer 19

the osteoid which is then calcified into bone

Question 20

process of osteogenesis

Answer 20

osteoblasts secrete collagen molecules and ground substance

collagen molecules combine to form collagen fibres

the resultant tissue is called osteoid (non-calcified bone)

hydroxyapatite crystals form on the collagen fibres. the osteoid is now calcified and this is bone

Question 21

steps of bone remodelling normally

Answer 21

Recruitment of osteoclast precursors.

These differentiate into mature multinucleated
osteoclast.

Osteoclasts adhere to an area of trabecular bone.

They dig a pit by secreting hydrogen ions and proteolytic enzymes, by a process called osteolysis.

This secretes cytokines such as insulin-like growth factor (IGF)-1 and TGF-β that have been embedded in the osteoid (the unminarilised component of bone).

These cytokines recruit and activate osteoblasts that have been stimulated to develop from precursor cells (osteoprogenitor cells).

Osteoblasts invade the site, synthesising and secreting the organic matrix of bone (the osteoid) and secreting IGF-1 and TGF-β (which become embedded in the osteoid).

The osteoid is then calcified into bone.

Some osteoblasts become embedded in the osteoid, forming terminal osteocytes.

Question 22

what is step 1 in bone remodelling following a fracture

Answer 22

haematoma formation:
a large blood clot closes off the injured vessels and leaves a fibrous meshwork in the damaged area

Question 23

what is step 2 in bone remodelling following a fracture

Answer 23

fibrocartilaginous callus formation:
an extensive internal callus organises within the medullary cavity and between the broken ends of the shaft

an external callus forms and encircles the bone at the level of the fracture

Question 24

what happens to the centre and edge cells in the external callus

Answer 24

at the centre, cells differentiate into chondrocytes and produce blocks of hyaline cartilage

at the edge, cells differentiate into osteoblasts and begin creating a bridge between the bone fragments on either side of the fracture

Question 25

what is step 3 in bone remodelling following a fracture

Answer 25

bony callus formation (callus ossification):
osteoblasts replace the central hyaline cartilage of the external callus with spongy bone (woven bone)

when this conversion is complete, the external and internal calluses form an extensive and continuous brace at the fracture site

struts of spongy bone now unite the broken ends

the ends of the fracture are now firmly held in place and can withstand normal stresses from muscle contractions

Question 26

what is step 4 in bone remodelling following a fracture

Answer 26

osteoclasts and osteoblasts continue to remodel the region of fractures from 4 - 12 months

when the remodelling is complete, living compact bone remains

the repair may be as good as new and leaves no indications that the fracture ever occurred, or the bone may be slightly thicker and stronger than the normal at the fracture site

under comparable stresses, a second fracture will generally occur at a different site