Lower Limb trauma Flashcards
What is primary bone union?
Via surgery - compression plating or lag screw fixation
Fragments are reduced absolutely, with no possible movement between the two ends.
Intramembranous ossification
Secondary bone union?
Natural means - normally helped along with a cast or splint
Endochondral ossification
How many phases of bone healing are there?
3
Describe phase 1 bone healing
Haematoma and inflammation
Platelet activation - inflammatory cascade via the release of growth factors and cytokines
Macrophages, fibroblasts, chrondroblasts, osteoblasts make their way there.
Fibroblasts and chondroblasts are laying down granulation tissue
Describe phase 2 bone healing
Callus formation with soft immature bone and cartilage
Osteoblastic differentiation and proliferation - production of the woven bone.
Osteoblasts will gradually mineralise the callus reducing movement at the # site.
Endochondral ossification - soft callus
What type of ossification creates hard callus?
Intermembranous
What type of ossification creates soft callus?
Endochondral
Describe phase 3 bone healing
Remodelling - takes years
Resorption by osteoclasts
Osteoblasts lay down hard lamellar bone
Callus decreases - trabeculae cross the site and medullary canal is created
What is strain theory?
The tissue that is laid down in a # site is dependent on the degree of movement between the bone ends –> mechanical signalling cascade
Wolff’s Law?
Bone remodels in response to mechanical stress - due to generation of piezoelectric charges from hydroxyapatite crystals, which alters the activity of osteoblasts and osteoclasts.
Factors affecting healing?
Degree of local trauma - surrounding soft tissue will greatly affect the healing rate.
- low energy trauma - spiral #’s
- high energy - comminuted #’s
Location of # - metaphysical quicker than diaphyseal
Metabolic bone disease, pathological tumours, osteporosis
Age, smoking, DM, HIV, medications (bisphosphonates, NSAIDS, quinolones)
Formula for kinetic energy? Why does this matter?
What does the 1st law of thermodynamics state?
KE = 1/2MVsquared
important as V is the only variable that will change dramatically in trauma.
Energy can neither be created nor destroyed.
1st law of thermodynamics
Energy can not be created or destroyed.
What is compartment syndrome?
When pressure in an anatomical compartment, where muscle is bound by fascia and bone, exceeds capillary perfusion pressure
6 Ps of an ischaemic limb
Pain, pulselessness, paraesthesia, perishingly cold, paralysis, pallor
