Mini Symposium - Fractures and Discloations Flashcards by Graeme Miller

What is a fracture?

Break in the structural continuity of bone

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What is the shorthand for fracture?

Hashtag

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Why do bones fail?

High energy transfer innormal bones

Repetitive stress in normal bones

Low energy transfer in abnormal bones

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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

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How do we describe fractures?

Mechanism & energy of injury
Skin & soft tissues
Site
Shape
Comminution
Deformity
Associated injuries

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What are the aims in treating fractures?

Relieving pain

Restoring function

Saving a life

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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

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What soft tissue can be affected from a fracture

Skin

Muscles

Blood vessles

Nerves

Ligaments

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What skin issues can develop after a fracture?

OPen fractures, degloving, Ischaemic necrosis

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When are muscles affected in a fracture?

Crush injury and compartment syndromes

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When are blood vessels affected in a fracture?

Vasospasm an arterial laceration

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When are nerves affected in a fracture?

–neurapraxias, axonotmesis, neurotmesis

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Joints?

Joint instability and dislocation

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How do soft tissue injuries affect healing?

Delays fracture healing time

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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

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Why do bones bleed when they break?

They are vascular

(unlike cartilage which is mostly avascular)

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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