PBL 5

Question 1

what is a delayed union

Answer 1

Delayed union = failure to consolidate within the normal timescale for that type of fracture and location

Question 2

what is a non union

Answer 2

failure to consolidate within 2x the normal expected time

Question 3

What are the causes of non union

Answer 3

• distraction at fracture site
• soft tissue loss
• bone loss
• soft tissue interposition
• poor blood supply
• haematoma
• infection
• poor splint age
• poor fixation
• age
• poor medical conditional
• NSAIDS
• fluoroquinolone

Question 4

What is pseudoarthrosis

Answer 4

formation of a false joint where a fibrocartilaginous cavity is lined with synovial membrane

Question 5

what cases do you supply stability for fracture healing

Answer 5

If biology good (i.e. there is a callus and a
blood supply then provide stability, correct
deformity a

If biology is poor then provide stability and
use a bone graft

If biology is bad then use a bone graft and
Other reconstruction and provide stability

Question 6

Name the different types of factors affecting bone healing

Answer 6

Local risk factors: open fractures, high energy fractures, severe associated soft tissue injury,
bone loss and infection

Iatrogenic factors: poor reduction, unstable fixation, bone devitalisation

Systemic factors: malnutrition, smoking, NSAIDs, systemic medical conditions (e.g. diabetes)
chronic alcoholism

Patient factors: non-compliance

Question 7

How do bone and joint infections work

Answer 7

• Local spread from adjacent tissues

haematogenous

• synovium = septic arthritis
• metaphysic = osteomyelitis
• direct inoculation or penetrating injury or surgery

Question 8

Describe the pathophysiology of osteomyelitis

Answer 8

• pus may enter the joint
• pus forms in the metaphysic
• in some joint capsule attaches below the growth plate
• pus escapes under periosteum and into soft tissues
• there is a sequestrum which is dead bone in the middle and new bone forms around this, this happens as blood supply is blocked

Question 9

How do you diagnose osteomyelitis

Answer 9

• serological studies
• CT
• indium labelled white blood cell scan
• bone culture
• CRP, ESR, WBC
• bone biopsy
• physical exam

Question 10

what is indium labelled WBC

Answer 10

anuclear medicinetest which attempts to localise infection and/or inflammation by injecting the patient’s previously extracted and radioactively-labelledwhite blood cells.

Question 11

How does indium labelled WBC work

Answer 11

• labelled with indium 111 Oxine and injected back into the patient
• patient needs to receive his or her own white blood cells back and careful systems must be put in place to ensure this occurs
• patient is imaged 24 hours later giving the white blood cells the opportunity to migrate to the site of inflammation and infection
• labelled leucocytes localise at the site of infection through diapedesis, chemotaxis and enhanced vascular permeability

Question 12

why did she have broad spectrum IV antibiotics

Answer 12

The cultures came back with a mixture of bacterial species so broad spectrum IV antibiotic therapy continued for 6 weeks.

Question 13

How do you treat osteomyelitis

Question 14

describe the treatment of osteomyelitis

Answer 14

• early testament includes local antibiotics delivery straggles for bony defect and adequate soft tissue coverage
• 6 week course of IV antibiotic based on biopsy
• at 6-8 weeks proceeded to second stage reconstruction with cement spacer removal and autologous bone grafting

Question 15

What are the types of bone graft

Answer 15

Autograft
Allograft (mineralised)
Allograft (demineralised)
Xenograft
Alloplast

Question 16

define autograft

Answer 16

a tissue or organ that isgraftedinto a new position on the body of the individual from which it was removed.

Question 17

define allograft

Answer 17

a tissue or organ obtained from one member of a species andgraftedto a genetically dissimilar member of the same species.

Question 18

define xenograft

Answer 18

agraftobtained from a member of one species and transplanted to a member of another species.

Question 19

define alloplast

Answer 19

an inert foreign body used for transplantation into tissues.

Question 20

what bone grafts are osteoinductive

Answer 20

• autograft

- allograft

Question 21

what bone graft is osteogenic

Answer 21

autograft

Question 22

define osteoconduction

Answer 22

Physical effect by which the matrix of the graft forms a scaffold that favours outside cells to penetrate the graft and form new bone

Question 23

define osteoinductive

Answer 23

Chemical process by which molecules contained in the graft convert the neighbouring cells into osteoblast

Question 24

define osteogenic

Answer 24

Formation or development of new bone cells contained in graft

Question 25

define osteopromotion

Answer 25

When the grafted material enhances osteoinduction

Question 26

what are the fracture union types

Answer 26

- clinical union | - radiologia union

Question 27

describe radiological union

Answer 27

- fracture line visible, no callus = 1 - visible fracture line and callus = 2 - no fracture line and visible callus = 3 - these are at anterior, posterior, lateral and medial levels - total score = minimum 4 and maximum 12

Question 28

define procurvatum

Answer 28

This refers to the movement of a single bone; where a procurvatum deformity describes backward bending of the bone and recurvatum deformity is the forward bending of the bone.

Question 29

What is the most common procurvatum

Answer 29

Most common is valgus and apex anterior (procurvatum)

Question 30

What is the most likely initial pathogenic organism that has caused the osteomyelitis?

Answer 30

Staphylococcus aureus

Question 31

2 Aside from autografts state two other alternatives as a bone graft. ( 2 marks)

Answer 31

Cadaveric irradiated bone (allografts) Xenograft | Alloplast (synthetic, hydroxyapatite, bioglass)

Question 32

From the information in the scenario which nerve has not regenerated and muscle group is still therefore denervated in Sana? (2 marks)

Answer 32

Common peroneal nerve | Anterior muscle compartment (dorsiflexors)

Question 33

Which white blood cells are the most likely to be tagged by the Indium white blood cell scan and in what state are these cells. (2 marks)

Answer 33

Neutrophils (1 mark) and active and alive (1 mark)

Question 34

Explain why the IV antibiotic treatment has to last 6 weeks? (3 marks)

Answer 34

Bone has a relatively poor blood supply (1 mark) especially the dead bone around the infection site (1 mark) so it is difficult to get enough antibiotic in to therapeutic levels for long enough to kill off all the bacteria (1 mark)

Question 35

What properties does an autograft possess that makes it ideal for treating nonunion?

Answer 35

Osteogenic: it provides a source of vital (living) bone cells Osteoinductive: it provides factors that recruit local mesenchymal cells to help repair the bone Osteoconductive: it provides a scaffold for the ingrowth of new bone cells.

Question 36

• What WBC would you find predominantly in the bone of patients with osteomyelitis and that sometimes can be also be an indicator in serology results

Answer 36

These PMN expressed MHC class II and produced interleukin (IL)-8, a further indication of PMN activation. To assess a possible link between infiltrating PMN and bone erosion, we tested the effect of IL-8 on osteoclast generation (look back at the RA pathophysiology lecture and the IL8 induction of macrophages and osteoclasts)