PBL 5 Flashcards
what is a delayed union
Delayed union = failure to consolidate within the normal timescale for that type of fracture and location
what is a non union
failure to consolidate within 2x the normal expected time
What are the causes of non union
- 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
What is pseudoarthrosis
formation of a false joint where a fibrocartilaginous cavity is lined with synovial membrane
what cases do you supply stability for fracture healing
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
Name the different types of factors affecting bone healing
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
How do bone and joint infections work
- Local spread from adjacent tissues
haematogenous
- synovium = septic arthritis
- metaphysic = osteomyelitis
- direct inoculation or penetrating injury or surgery
Describe the pathophysiology of osteomyelitis
- 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
How do you diagnose osteomyelitis
- serological studies
- CT
- indium labelled white blood cell scan
- bone culture
- CRP, ESR, WBC
- bone biopsy
- physical exam
what is indium labelled WBC
anuclear medicinetest which attempts to localise infection and/or inflammation by injecting the patient’s previously extracted and radioactively-labelledwhite blood cells.
How does indium labelled WBC work
- 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
why did she have broad spectrum IV antibiotics
The cultures came back with a mixture of bacterial species so broad spectrum IV antibiotic therapy continued for 6 weeks.
How do you treat osteomyelitis
describe the treatment of osteomyelitis
- 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
What are the types of bone graft
Autograft Allograft (mineralised) Allograft (demineralised) Xenograft Alloplast
define autograft
a tissue or organ that isgraftedinto a new position on the body of the individual from which it was removed.
define allograft
a tissue or organ obtained from one member of a species andgraftedto a genetically dissimilar member of the same species.
define xenograft
agraftobtained from a member of one species and transplanted to a member of another species.
define alloplast
an inert foreign body used for transplantation into tissues.
what bone grafts are osteoinductive
- autograft
- allograft
what bone graft is osteogenic
autograft
define osteoconduction
Physical effect by which the matrix of the graft forms a scaffold that favours outside cells to penetrate the graft and form new bone
define osteoinductive
Chemical process by which molecules contained in the graft convert the neighbouring cells into osteoblast
define osteogenic
Formation or development of new bone cells contained in graft
define osteopromotion
When the grafted material enhances osteoinduction
what are the fracture union types
- clinical union
- radiologia union
describe radiological union
- 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
define procurvatum
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.
What is the most common procurvatum
Most common isvalgus andapex anterior (procurvatum)
What is the most likely initial pathogenic organism that has caused the osteomyelitis?
Staphylococcus aureus
2 Aside from autografts state two other alternatives as a bone graft. ( 2 marks)
Cadaveric irradiated bone (allografts) Xenograft
Alloplast (synthetic, hydroxyapatite, bioglass)
From the information in the scenario which nerve has not regenerated and muscle group is still therefore denervated in Sana? (2 marks)
Common peroneal nerve
Anterior muscle compartment (dorsiflexors)
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)
Neutrophils (1 mark) and active and alive (1 mark)
Explain why the IV antibiotic treatment has to last 6 weeks? (3 marks)
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)
What properties does an autograft possess that makes it ideal for treating nonunion?
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.
• 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
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)
