MSK Flashcards
(94 cards)
what are the differentials of osteomyelitis
soft tissue infection/cellulitis charcot joint avascular necrosis gout fracture bursitis malignancy
define acute osteomyelitis
associated with inflammatory bone changes caused by pathogenic bacteria
present within 2 weeks
define chronic osteomyelitis
involves BONE NECROSIS
symptoms not until 6 weeks after onset infection
describe haemotagenous OM in the long bone
metaphysis = common site of infection
blood vessels penetrate midshaft then go to either end = metaphysis
at metaphysis blood flow is slower and no BM present and no phagocytes lining the capillaries so bacteria moves easily from blood to bone
why does OM occur in long bones of children
metaphysis very metabolically active due to growth
= large flow of blood to this area = higher chance of infection
why does OM occur in vertabrae of elderly
with age vertebrae = more vascular = more blood flow and higher chance of infection
what microbial factors help cause OM
different bacteria have different virulence factors
some bacteria e.g. S.aureus bind more easily to fibronectin, fibrinogen and collagen = easier cause OM
describe the hostological changes in acute OM
- bacteria reach bone and proliferate
- dendritic cell/macrophage activation
- immune system breaks down and destroys bacteria
- osteoblast/clast repair damaged bone
- resolution
describe the histological changes in chronic OM
- necrotic bone
- formation of sequestrum
- osteoblast form new bone around sequestrum = involucrum
- periosteum loosely attached to compact bone
- abscess formation
- tracking to nearby joints/muscles/skin/blood vessels
describe mycobacterium osteomyelitis
= extrapulmonary TB
slower onset and symptoms
biopsy essential for diagnosis
longer treatment = 12 months
what is gonococcal arthritis
joint infection caused by neisseria gonorrhoea
affects multiple joints
causes fever, arthritis, tenosynovitis and maculopapular pustular rash
what primary tumours are most likely to metastasis to bone
kidney = lytic prostate = sclerotic thyroid = lytic breast = lytic
what does lytic mean
bone destructive
what does sclerotic mean
bone forming
name the 5 most common primary bone tumours
- multiple myeloma = lytic
- hodgkin lymphoma = sclerotic
- ewing’s sarcoma = lytic
- osteosarcoma = lytic
- chondrosarcoma = lytic, sclerotic at higher grades
what are the red flags for bone malignancy
night pain weight loss rapid deterioration gross loss of movement infection non-mechanical
how does Paget’s present on XR
moth eaten bones
median nerve examination of hand
ask patient to make OK sign
check sensation of radial 3 digits on palm
median nerve palsies = loss of flexion in the two index fingers
radial nerve examination of hand
check patient can point with index finger
check sensation on back of hand of radial 3 and half digits
radial nerve palsies typically present with wrist drop
ulnar nerve examination of hand
ask patients to cross fingers
check sensation on ulnar side of hand
ulnar nerve palsies = claw hand as individuals unable to extend fingers
name 3 types of hip fracture
- sub-trochanteric
- intertrochanteric = always fixable
- intracapsular = likely chance of avascular necrosis if femur head displaced
what are the key principles of fracture management
reduction
stabilisation
rehabilitation
what is the number 1 cause of death for ages 1-46
trauma
define a fracture
soft tissue injury with loss of continuity of bone