Flashcards in Fractures and Dislocations Deck (35):
What is a fracture?
Break in structural continuity of bone
May be a crack, break, split, crumpling or buckle
Give 3 broad reasons why bones fail
High energy transfer in normal bones:
-Takes a lot
Repetitive stress in normal bones:
Low energy transfer in abnormal bones:
-Osteomalacia, metastatic tumour
-Other bone disorders
What is Wolff's law in relation to bone shape?
Bone is laid down where it is needed and removed where it is not needed
("form follows function")
What 7 criteria should you cover when you are describing a fracture?
-Mechanism and energy of injury
-Skin and soft tissues
What are the 3 aims in treating fractures?
What is the key to understanding fractures?
SOFT TISSUE DAMAGE
(fractures are a form of soft tissue damage with a broken bone)
How will a severe soft-tissue injury effect fracture healing?
All severe soft tissue injuries require urgent treatment.
Give some examples
There are many different treatments for fractures
What does your choice depend on?
Abilities of surgeon (!)
What percentage of fractures have delayed or impaired healing?
How does fracture healing differ from soft injury repair?
(Think about how bone and soft tissue heal)
Soft tissues heal by replacing injured tissue with a fibrous scar
Bone heals by regeneration of normal bony anatomy
Bone heals by the formation of callus
What is callus?
An intermediary stabilising structure fromed after a fracture, which has cartilaginous grwoth plate characteristics and results in eventual
Descrube the 3 phases of bone healing
-10% of healing time
-From 2 days
-Chondral and osseous
-40% of healing time
-From middle of repair phase
-70% of healing time
(NOTE: phases overlap so percentage healing time wont add up to 100)
Describe the 7 cellular events in fracture repair
(Immediate response to injury)
Release of vasoactive mediators (e.g. nitric oxide), cytokines
Proliferation of undifferentiated cells - migration, recruitment, proliferation, differentiation
Invasion by inflammatory cells (macrophages, PMNs)
Organisation of clot into fibrous tissue by fibroblasts
Formation of reparative granuloma
Vessel thrombosis and osteocyte death
Describe the 4 cellular events in intra-membranous ossification
Differentiation of osteo-progenitor precursor cells into osteoblasts
Collagen deposited along fibrin scaffold - new bone matrix synthesis (osteoid from osteoblasts - uncalcified mass = primary callus)
Bone formation in periosteum (woven bone) - converts primary external callus into hard secondary callus - clinical union)
Describe the 5 cellular events in endochondral ossification
Bone formation in callus similar to bone formation in growth plate
Osteoblasts follow capillary ingrowth
Synthesis of osteoid (un-calcified mass) - becomes mineralised to give speckled calcification
Formation of "mixed spiculae" (immature bone and cartilage)
Bridging of fracture gap - radiological union
Describe the 8 cellular events in remodelling
Osteoblastic and osteoclastic activity
Osteoclastic cutting cones
Remodelling of woven bone, according to Wolff's law
Lamellar bone more efficient, so volume decreases
Cancellous bone remodels at trabecular level
Remodelling of some deformities but not others
Measurement of fracture healing can be done by 4 different methods.
One of which is clinical examination. When should this be done for adults and children in lower and upper limbs?
-Adult -> 6-8 weeks
-Child -> 3-4 weeks
-Adult -> 12-16 weeks
-Child -> 6-8 weeks
How can radiological measurement determine fracture healing?
Bridging callus formation
How can you biomechanically measure fracture healing?
When is a frcature healed?
When patient can bear weight
When X-ray says so
When remodelling complete
What host factors can influence fracture repair?
Nutritional and hormonal status
What local factors influence fracture repair?
Soft tissue injury
Type of bone
Give 4 bony problems of fracture healing
What is mal-union?
Fracture has healed, but not in an anatomically-correct position
What is delayed union?
Healing takes longer than average for that fracture in that individual
What is nonunion?
No further progress towards union
What problems with treatment may lead to delayed or non-union?
Distraction of fracture by fixation device or traction
Periosteal stripping and soft tissue damage at operation
Anatomical vascular suspectibility
-e.g. femoral neck, scaphoid, talus (distal tibia)
What is the difference between the 3 types of non-union?
-Gap at # site, bone loss- soft tissue interposition or pathological bone- infection, tumour, AVN etc
-Attempt at healing, but # site too mobile
-horses hoof, elephant's foot
How do you manage infeted non-union?
Remove dead, devitalised and infected tissue
Obtain organism (if possible)
Treat infection and stabilise fracture
What is avascular necrosis?
What classical fractures does it occur?
Loss of blood supply
Any bone fragment stripped of soft tissue attachments
-Hip (intracapsular - NoF)
What is the aim of fracture management?
What are the aims of treating fractures?
What score can you use to determine when it may be best to perform an amputation?
Mangled Extremity Severity Score (MESS)