Mini Symposium - Fractures and Discloations Flashcards
What is a fracture?
Break in the structural continuity of bone
What is the shorthand for fracture?
Hashtag
Why do bones fail?
High energy transfer innormal bones
Repetitive stress in normal bones
Low energy transfer in abnormal bones
For what reasons might bones be susceptible to fracture?
Osteoporosis
Osteomalacia, metastatic tumour
Other bone disorders
- Osteomalacia is the softening of bones especially through vitamin D or calcium deficiency
How do we describe fractures?
- Mechanism & energy of injury
- Skin & soft tissues
- Site
- Shape
- Comminution
- Deformity
- Associated injuries
What are the aims in treating fractures?
Relieving pain
Restoring function
Saving a life
Give examples of life saving support as a result of fractures?
Reducing a pelvic fracture in a haemodynamically unstable patient
Applying pressure to reduce haemorrhage from open fracture
What soft tissue can be affected from a fracture
Skin
Muscles
Blood vessles
Nerves
Ligaments
What skin issues can develop after a fracture?
OPen fractures, degloving, Ischaemic necrosis
When are muscles affected in a fracture?
Crush injury and compartment syndromes
When are blood vessels affected in a fracture?
Vasospasm an arterial laceration
When are nerves affected in a fracture?
–neurapraxias, axonotmesis, neurotmesis
Joints?
Joint instability and dislocation
How do soft tissue injuries affect healing?
Delays fracture healing time
How does soft tissue repair compare to bone repair?
Soft tissue heal by replacing injured tissue with a fibrous scar
Bone heals by regeneration of normal bony anatomy
Why do bones bleed when they break?
They are vascular
(unlike cartilage which is mostly avascular)
A bone heals by forming a callus, what is a callus?
(“an intermediary stabilising structure formed after a fracture, which has cartilaginous growth plate characteristics and results in eventual enchondral ossification”)
What are the three stages of bone healing?
Inflammatory
Reparative
Remodelling
What are the cellular events in fracture repair (immediate reponse to repair?)
- Haematoma formation
- 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
Haematoma - mediators - cellular change (proliferation and invasion) - clot becomes fibrous tissue - granuloma - vessel thrombosis and osteocyte death.
What are the stages of intra-membranous ossification?
- Differentiation of osteo-progenitor
precursor cells into osteoblasts
- Angiogenesis
- 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
bone is formed in sheet-like layers that reseamble a membrane
(osteoprogenitor cells become osteoblasts - angiogenesis - collagen deposition - primary callus - secondary callus)
How does bone from from a callus?
Endochondral ossification
What are the stages of 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
Endochondral ossification - bone is formed from cartilgae mode
What are the stages of remodelling?
- osteoblastic & osteoclastic activity
- osteoclastic cutting cones
- consolidation
- remodelling of woven bone, according to Wolff’s law
- lamellar bone more efficient, so volume decreases
- cancellous bone remodels at trabecular level
- longest stage
- remodelling of some deformities,
but not others
Lamellar bone has a regular allignment of collagen and is mechanically strong
What are the phases of bone healing?
Inflammatory (24-72h)
Reparative (from 2 days chondral + osseus)
Remodelling (osseus)
What is the difference between primary bone union and secondary bone union?
Primary bone union - involves a direct attempt by the cortex to re-establish itself after interruption without the formation of a fracture callus. Only works when the edges are touching exactly.
Primary bone union only happens in surgical fixation or unicortical fracture (partial crack in the bone)
Primary bone healing is lead by a cutting cone (osteoclasts at the front removing bone and osteoblasts laying down bone)
SLOW
Secondary bone healing closely follows endochondral ossification (cartilage template is replaced by bone)
Wolff’s law - bone is layed down according to forces applied to the bone
How long does it take for fractures to heal?
When is a fracture healed?
When a patient can bear wight
WHen X-ray says so
When remodelling is complete
Bones heal without scars
What is the difference between problems and complications?
Problems are treatable and complications are preventable
What are systemic problems associated with fracture?
Hypovolaemia
Cruch syndrome
Fat embolism and ARDS
Psychological and social aspects
What are the systemic complications associated with fracture healing?
Bed rest comlpications (DVT and PE)
Tetanus
What are the local problems associated with fractures?
Neurovascular damage
Skin wound problems
Compartment syndrome
Delayed union
Non-union
Avascular necrosis
What are some of the local complications associated with fracture?
Infection
Malunion
CRPS type 1
Joint stiffness
What are the host factors influencing fracture repair?
Nutritional and hormonal status / drugs / CNS injury
What are the local factors affecting fracture repair?
soft tissue injury / bone loss / radiation / tumour / distraction / tissue interposition / blood supply / infection / type of bone / synovial fluid
What are the bony problems of fracture healing
- Delayed union
- Non-union
atrophic, hypertrophic, infected
- Mal-union (described as a complication and not a problem in the previous slide)
- Avascular necrosis
What are the causes of delayed or non-union of bones?
- inadequate immobilisation
- distraction of # by fixation device or traction
- repeated manipulations
- periosteal stripping & soft tissue damage at operation
- anatomical vascular suspectibility, eg. femoral neck, scaphoid, talus, (distal tibia)
So the bone is moving around to much (because the immobalisation is not effective or there are too many manipulations, the envelope that is the periosteum has been stripped or there is soft tissue damage, or the bone is susceptible to delayed union as a result of poor vascularity)
What is the difference between atrophic and hypertrophic non-union?
Atrophic - •(gap at # site, bone loss - soft tissue interposition or pathological bone – infection, tumour, AVN, etc.)
• Hypertrophic (attempt at healing, but # site too mobile)
(horse’s hoof, elephant’s foot)
What are the sources of atrophic non-union when the cause is infection?
- contamination in open fracture
- introduction at time of operation
- multiple operations
- unstable fixation
- metastatic sepsis on foreign body implant
- immunologically compromised patients
How do you manage infected non-union?
Remove dead, devitalised tissue and infected tissue
Obtain the organism
Treat infection and stabilised the fracture
What are the calssical sites of avscular necrosis?
head of femur, neck of talus and waist of the scaphoid. Avascular necrosis most commonly affects the ends of long bones such as the femur
There are lots of treatment options see 2676_mini_symposium_fractures_open_fractures_dislocations_principles_of_management
