Injury And Healing Flashcards
What are the mechanisms of bone fracture?
Trauma: low or high energy
Stress: abnormal stress on normal bone
Pathological: normal stress in abnormal bone
What are stress factors?
Overuse —>
Stress exerted on bone> capacity to remodel bone —>
Bone weakening —>
Stress fracture —>
Risk of complete fracture
Occurs often in Weight bearing bones: femur, tibia, metatarsals, navicular
Activities: atheletes, occupational, military, female athlete triad (disordered eating, osteoporosis, amenorrhoea)
What are are pathological/insufficiency fractures?
The pathology causes weakened bone that is more likely to fracture
Pathology can be local or general
Local: osteomyelitis, malignancy
General: osteoporosis, osteogenesis imperfecta, vitamin D deficiency
Most common is osteopenia or osteoporosis (can be localised or generalised) (can be primary(age) or secondary(hormonal))
What are some features about osteoporosis (insufficiency factor)?
Normal -> osteopenia -> osteoporosis
Osteoclast activity > osteoblast activity
Female:male 4:1
Can have post menopausal osteoporosis
Can be local or generalised
Primary: old age
Secondary: any age, due to hormones (hypogonadism, glucocorticoid excess, alcoholism)
Associated with fragility fractures (hip, spine, wrist)
Low energy trauma-> fracture
What are some features of vitamin D deficiency (insufficiency)?
Vitamin D facilitates calcium, magnesium and phosphate absorption
Dietary or synthesised from the sun
Inadequate calcium/phosphate-> defect in osteoid matrix mineralisation
Children-rickets
Adults-osteomalacia
What are some features of osteogenesis imperfecta (insufficiency) ?
Congenital- brittle bone disease
Decreased type 1 collagen: decreased secretion/production of abnormal collagen
Hereditary - autosomal dominant or recessive
Effects: weak bones, short stature, impaired hearing, blue sclera, impaired sight
What are some features of Paget’s disease (insufficiency)?
Genetic and acquired factors
Excessive bone breakdown and disorganised remodelling -> deformity, pin, fracture and arthritis
May transform into a malignant disease
4 stages: osteoclast activity. Mixed osteoclastic-odteblastic activity. Osteblastic activity. Malignant degeneration
Are pathological and insufficiency fractures the same?
Kinda almost but basically
Pathological is more cancer or infection
What are some features of malignancy (pathological fractures)?
Primary bone cancer: osteosarcoma, chondrosarcoma, Ewing sarcoma, lymphoma
Secondary: metastases
Metastases most commonly come from:
Prostate (blastic)
Breast (blastic/lytic)
Kidney (lytic)
Thyroid (lytic)
Lung (lytic)
How do we describe fractures?
Soft tissue integrity: open/closed
Bony fragments: greenstick(bent)/simple(closed)/multifragmentary(comminuted)
Movement: displaced/undisplaced
How (generally) do fractures heal?
Most things follow the basic pathway:
Bleeding->inflammation->new tissue formation->remodelling
So with bone:
Blood->neutrophils,macrophages-> BLASTS (fibro,osteo,chondro)-> macrophages, osteoclasts, blasts
How (specifically) does fracture healing occur?
Inflammation:
Haematoma formation at the broken ends of bone
Release fo cytokines
Granulation of Tissue and blood vessel formation
Repair:
Soft callus formation (type II collagen - cartilage)
Converted to hard callus (type I collagen - bone)
Remodelling:
Callus responds to activity, external forces, functional demands and growth
Excess bone is removed
(Wolffs late: bone grows and remodels in reaponse to the forces that are placed on it)
What are primary and secondary bone healing?
Primary:
Inteamembraneous healing (see intro lecture)
Absolute stability
Direct to woven bone
The ends of the bone are basically in the right place at the beginning but are fixed together with a plate
Secondary:
Endochondral healing
Involves responses in the periosteum and external soft tissues
Relative stability
Endochondral ossification: more callus
What are the fracture healing times?
3-12 weeks depending on site
Signs of healing Visible on X ray from 7-10 days
Phalanges: 3 weeks
Meta carpals: 4-6
Distal radius : 4-6
Forearm: 8-10
Tibia: 10
Femur: 12
What are the general principles for fracture management?
Reduce: bring fractured ends back together. Open/closed
Hold: them together. Metal/no metal
Rehabilitate: move/physiotherapist/use
