Lecture 1 - finished Flashcards
What is the healing timeline for fractures
Haematoma formation - first 2-3 days
Acute inflammation - first 3-5 days
Granulation tissue/ procallus formation - 3-7 days post fracture
Fibrocartilagenous callus formation - starts 1 week post fracture and lasts up to 3 weeks
Bony callus formation - starts 3-4 weeks post fracture and finishes about 2-3 months later
Remodelling - starts during bony callus formation and continues for several months
Fracture definition
A break in the continuity of bone
Clinical manifestations of OM in adults
Insidious onset of:
- vague ssx
- fever
- malaise
- anorexia
- weight loss
Recent Hx of:
- Infection
- Instrumentation
Stages of fracture healing:
Stage 1: Fracture occurs
Stage 2: Haemorrhage and haematoma formation
- extravasated blood clots to form a haemotoma
- inflammation is initiated
- Activation of local inflammatory cells and migration of these cells into the region
- Activation and proliferation of local connective tissue cells
= Osteoblasts, osteogenic cells, fibroblasts, chondroblasts
Stage 3: Procallus formation/ organisation of the haematoma
- Haematoma is replaced by granulation tissue
- In this stage:
= Phagocytes remove debris
= Osteoblasts make woven bone (limited because of slow neovascularisation rate)
= Fibroblasts make collagen
= Chondroblasts make cartilage
= Blood vessels grow into the region
Stage 4: Fibrocartilagenous callus
- All cells within the procallus makes massive amounts of cartilage and collagen
- Woven bone is formed but still limited
- As the cartilage and collagen amounts increase the granulation tissue gives way to fibrocartilagenous tissue.
Stage 5: Bony Callus formation
- In this stage we see:
= increased neovascularisation
= increasing mineralisation of osteiods
= destruction of fibrocartilagenous tissue by osteoclasts
= increased synthesis of woven bone
- This forms a bony callus which reunites the ends of fracture.
Stage 6: Remodelling
- In this stage osteoclastic activity is greater than osteoblastic activity
- Woven bone is destroyed and replaced with lamellar bone (which is laid down in concentric layers to form osteons)
- Internal and external calluses are reabsorbed.
Diagnosis of osteomyelitis
Hx and clinical exam Biopsy: needle aspiration Blood tests: - cultures (+ve in 50% of cases) - Increased WBC, CRP and ESR
Imaging:
- Radiography (bone infection not evident for 14-21 days)
- MRI (good for early detection)
- Radionuclide bone scanning
- CT
- US
Complications of #
Delayed union Non union Pseudarthrosis Malunion Bone necrosis Compartment syndrome Fat embolism Infection Shock Local soft tissue injury
Local causes of delayed healing time
Malalignment Excessive movement Comminution Bone disease Severe soft tissue injury Infection Ischemia Soft tissue interposition
What is the definition of a pathological fracture?
When a small/moderate force acts on a weakened of diseased bone causing a fracture
Clinical manifestation of vertebral OM
Back pain:
- Intermittent or constant
- worse with motion
- throbbing at rest
- -/+ radicular distribution
Spinal tenderness and rigidity
Hip contracture secondary to psoas irritation
Why is fracture classification important?
So we can assess: Occurrence (how it happened) Seriousness Type of treatment required Prognosis Complications Stability of fracture
Osteomyelitis definition
Inflammation of bone caused by bacteria
occasionally caused by mycobacteria or fungi
Pathogenesis of osteomyelitis in children
Transient bacteremia
Bacteria reach the bone
Inflammation of bone
- inflammation spreads through haversian canals and causes compression of adjacent blood vessels.
Bone necrosis and abscess formation
Sequestrum
- dead bone separates from living bone
Reactive bone growth:
- inflammatory exudate may extend to the surface of the cortical bone; abscesses and oedema form and cause elevation of the periosteum.
- periosteal elevation disrupts the blood supply to the bone in that area and deprives underlying bone of blood supply
- lifting of the periosteum also stimulates intense osteoblastic activity which results in the formation of new bone (involucrum) which may surround the affected bone.
Sinus formation:
- pus and necrotic tissue from the infection focus may drain towards the surface of the skin.
- superficial drainage site is called the cloaca.
Local ssx of #
- Deformity
- Oedema
- Pallor
- Bruising/erythema
- Loss of function
- Palpation will reveal - pulselessness, tenderness, paresthesia
- Movement will reveal - crepitation, muscle spasm, abnormal movement
OM on plain film x-ray
First manifestation:
- soft tissue oedema 3-5 days post infection
Bony changes:
- initial periosteal elevation
- subperiosteal bone formation (involucrum)
- cortical and medullary radiolucencies as bone is destroyed
(** remember that bone loss has to be 40-50% for it to be evident on x-rays)
Causes of Physiological Fractures
Fatigue
Accident
Unusually strong muscle contractions
Prolonged/repetitive physical stress
Signs of fat embolism
Hypoemia Tachypnoea Fever of unknown origin Chest pain Altered mental status Possibly petechiae
Classification types for fracture
According to aetiology
- physiological
- pathological
According to the site of force on the bone
- direct
- indirect
According to visual characteristics - spiral - transverse - oblique - chip etc
According to the extent of the fracture - greenstick - comminuted (many pieces) - complete (2 pieces) etc
According to whether the overlying skins is broken
- simple
- compound (broken overlying skin)
According to joint involvement
- intracapsular
- extracapsular
Common fractures:
Colles - distal radius
Potts - eversions sprain causing avulsion of med mal and fracture of lat mal
Define cloaca:
Superficial drainage site for the focus of infection in the underlying bone in OM
Systemic causes of delayed healing time
Mineral deficiency Vitamin deficiency Comminution Systemic infections Bone disease Ischemia (atherosclerosis) Endocrine disease Medications Poor general health Advanced age
Clinical manifestations of OM in children
Sudden onset of high fever, chills and nausea
Progressively increasing local pain
Local muscular spasm
Local oedema and warmth of the soft tissues
General ssx of #
Shock
Ssx secondary to other organs damaged eg viscera, CNS
Ssx due to underlying pathology
6 signs of compartment syndrome
Pain Pulselessness Perishingly cold Paraesthesia Paralysis Pallor (Pressure increase)
What are the differences in bone usually affected by OM between children and adults?
Adults: usually spine, pelvis or small bones
Children: usually the metaphysis of long bones
Fracture epidemiology
Young people - 15-24 - tibia - clavicle - lower humerus Usually secondary to trauma
Old people - 65+ - Upper femur - upper humerus - vertebrae - pelvis Usually secondary to osteoporisis
What affects bone healing times
Age
Type of #
Bone #’d
Health of patient
What is the most common scenario for osteomyelitis?
Haematogenous spread of staphylcoccus aureus from an unknown primary site
Pathogenesis of osteomyelitis in adults
Transient bacteremia
Bacteria reach the bone
Inflammation of bone
- inflammation spreads through haversian canals and causes compression of adjacent blood vessels.
Bone necrosis and abscess formation
Sequestrum
- dead bone separates from living bone
What are the main forms of spread of bacteria into bone?
Contiguous
- dental
- cutaneous
- sinus
- aural
Traumatic
Haematogenous
Causes of Pathological fractures
Focal bone disease
Metabolic disorders
Disuse
Do adults get the reactive bone growth and sinus formation stages of OM?
No, because the periosteum is firmly attached to the bone cortex in adulthood and resists displacement
What is the definition of a physiological fracture?
When a strong external force acting on a normal bone exceeds the mechanical strength of the bone
