dislocations

Question 1

what is the mechanism of shoulder dislocation?

Answer 1

fall, traction, injury

Question 2

what is the most common shoulder dislocation?

Answer 2

most commonly displaces anteriorly,
caused by fall with shoulder in external
rotation,
humeral head displaced anterior to the glenoid,
axillary nerve = regimental badge area
sensory assessment (axillary nerve can be damaged)

Question 3

what is a posterior shoulder dislocation?

Answer 3

tend to be people with seizures (usually due to the muscle spasms, not
necessarily the fall), light bulb sign, can also occur in fall with shoulder in internal rotation/direct
bloc to anterior shoulder, humeral head displaces posterior to the glenoid

Question 4

what is an inferior shoulder dislocation?

Answer 4

RARE, arm held in abduction, humeral head displaced inferior to the
glenoid, needs prompt neurovascular assessment and reduction

Question 5

what is an associated injury with many shoulder dislocations?

Answer 5

labral tears etc.

Question 6

management of shoulder dislocation?

Answer 6

closed reduction (not surgical) under sedation
open reduction
stabilisation and
rehabilitation
Reduction methods: hippocratic, in-line traction
Once joint is reduced, need to make sure function fully returns (physio, rehab, may need surgical
operations)
Recurrent instability risk: related to age, risk of recurrence decreases with age

Question 7

what is the mechanism of elbow dislocation?

Answer 7

Tends to occur in children (holding parents hand - pulled elbow), adults - sporting activities etc.)
Mechanism - usually fall onto outstretched hand

Question 8

what damage can be caused by an elbow dislocation?

Answer 8

directions - posterior, anterior medial/lateral
Small risk of radial head and coronoid process fractures
Elbow is usually pretty stable due to ligaments and stabilisers
Ante cubital fossa: neurovascular structures

Question 9

how is an elbow dislocation managed?

Answer 9

closed reduction under sedation, rarely need open reduction, 2 weeks in sling and
rehabilitation
Reduction methods: traction in extension +/- pressure over olecranon
Recurrent instability risk is low!

Question 10

what is the mechanism of an interphalangeal joint dislocation?

Answer 10

Hyperextension injury, direct axial blow - like a football hitting the finger
- almost always posterior (dorsal)

Question 11

how is an interphalangeal joint investigated?

Answer 11

Again be aware of any damaged neurovascular structures
Possible pitfalls: head of phalanx button-holes through volar plate, recurrent instability due to
associated fracture
Doing X-rays helps to see if there’s an associated fracture (even if you can clearly see the
dislocation)

Question 12

how is an interphalangeal joint dislocation managed?

Answer 12

closed reduction under digital/metacarpal block (ring block) - numbs the finger,
then pull it back, so open reduction is really rare, 2 weeks in neighbour strapping, volar slab in
Edinburgh position if unstable
Reduction methods: in-line traction and corrective pressure
Hand kept in this position (rehab) for function - to prevent tendon contraction in an abnormal way
(natural hand position):

Question 13

what is the first thing to do with a patella fracture?

Answer 13

CONFIRM whether it’s a patella dislocation OR

knee dislocation - very different (has different mechanisms

Question 14

what is the mechanism of patella dislocation?

Answer 14

sudden quads contraction with a flexing knee

Question 15

who gets a patella dislocation?

Answer 15

Most common in teenagers (and more common in girls) 
Associations/causes: 
hyper-mobility, 
under-developed 
(hypoplastic) lateral femoral condyle,
increased Q-angle 
(genu valgum, increased femoral neck anteversion), 
lateral 
quads insertions or 
weak vastus medialis

Question 16

what else can be injured in a patella dislocation?

Answer 16

Can have torn MPFL (medial patella femoral ligament)

always lateral dislocation and often self-relocating

Question 17

how is a patella dislocation examined?

Answer 17

pain medially (from torn medial retinaculum),
effusion (haemarthrosis),
positive patella apprehension test

Question 18

how is patella dislocation managed?

Answer 18

reduce with knee extension,
radiographs, 
aspiration, 
brace, 
physiotherapy

if repeat dislocations
surgery:
lateral release/medial reefing,
patella tendon realignment

Question 19

what is the mechanism of knee dislocation?

Answer 19

Usually high energy (velocity) injuries, can be from low energy injuries
Is there spontaneous relocation? - not a diagnosis to be missed, LCL injury + peroneal nerve
injury = dislocation

Question 20

If knee is swollen but looks fine on an X-ray and nothing else seems wrong?

Answer 20

knee is reduced,
pulses and sensations are intact), remember to exclude knee dislocation - so OBSERVE (small
tear may get worse, instability etc.

Question 21

how is a suspected knee dislocation managed?

Answer 21

orthopaedic emergency
Normal exam = observe in hospital, clinical concert = arteriogram/MRI
Check ligamentous stability examinations - may have to do this under anaesthetics
Urgent management: reduction under sedation, may need theatre reduction if condyle buttonholed through capsule, stabilise in splint or external fixation (which is basically just another type
of splint)

Question 22

what are the possible injuries which can accompany knee dislocation?

Answer 22

Vascular injuries: popliteal artery/vein injury, may not be obvious (intimal tear/thrombus)
Nerve injuries: peroneal nerve

Question 23

how is a knee dislocation diagnosed?

Answer 23

plain radiographs, there are associated fractures, MRI

Question 24

What surgery is done for a knee dislocation?

Answer 24

Early - vascular repair (6hr window), nerve repair
Definitive - sequential ligamentous repair
Complications: arthrofibrosis and stiffness, ligamentous laxity, nerve/arterial injury

Question 25

what is the mechanism of injury for a hip dislocation?

Answer 25

Pretty rare
Mechanism: high velocity (RTA dashboard injury, fall from height etc.)
the hip is a very stable joint
- to dislocate a native hip it takes a lot of energy

Question 26

how does a hip dislocation present?

Answer 26

flexed

internally rotated and adducted knee

Question 27

how is a hip dislocation managed?

Answer 27

Important to differentiate whether it’s a prosthetic or native hip
Rare to see this in isolation, need to remember to exclude other things
Early management: neurovascular assessment (sciatic nerve), radiographs (changes can be
subtle), urgent reduction, stabilise in tractions if required, further imaging (CT)
Definitive management: fixation of associated pelvic fractures, fixation of other injuries in polytrauma patients

Question 28

what are the complications of hip dislocations?

Answer 28

sciatic nerve palsy,
AVN of the femoral head,
secondary OA of hip

Question 29

what way does the hip dislocate?

Answer 29

Dislocated posteriorly

Associated with posterior acetabular wall and femoral fractures