6: Common dislocations Flashcards
Most fractures are reduced by which means?
Closed reduction
skin is CLOSED e.g by manipulation
If soft tissues are in the way of a dislocation, how are they reduced?
Open reduction
i.e surgically
What can be compromised by a joint dislocation?
Neurovasculature
nerves, arteries, veins
The vast majority of shoulder dislocations are (anterior / posterior).
Why?
anterior
bony, muscular shield posteriorly
What is an atraumatic cause of shoulder dislocation?
In which genetic conditions can it be seen?
Hypermobility (i.e ligamentous laxity)
Marfan’s syndrome, Ehlers-Danlos syndrome
Which movement can produce an anterior shoulder dislocation?
Extreme external rotation
Why can falling onto the elbow produce an anterior shoulder dislocation?
Superior translation of shoulder causes it to dislocate anteriorly
Which nerve may be compromised by an anterior shoulder dislocation?
Axillary nerve
What is a sign of axillary nerve injury following an anterior shoulder dislocation?
Loss of sensation in regimental badge patch area
What structures other than the axillary nerve may be injured by an anterior shoulder dislocation?
Axillary artery
Brachial plexus
Glenoid labrum
Posterior head of humerus
Rotator cuff muscles
What are the names for lesions associated with the
a) glenoid labrum
b) posterior head of the humerus
in anterior shoulder dislocations?
a) Bankart lesion
b) Hill-Sachs lesion
How are shoulder dislocations usually reduced?
Manually
i.e a closed fixation
The chances of recurrent shoulder dislocation (increases / decreases) with age.
decreases with age
What is the management of most shoulder dislocations?
Reduce
Fix (closed fixation e.g immobilisation with a sling)
Physiotherapy
How may rotator cuff tears be treated if they are causing impingement syndrome?
Subacromial decompression
Rotator cuff repair
What specific nerve injury is usually associated with axillary nerve compression in shoulder dislocations?
Neurapraxia
resolves within a month
What is the nerve injury one step up from neurapraxia which may occur in shoulder dislocation and may not resolve?
Axonotmesis
Which nerve supplies the deltoid muscles?
Axillary nerve
so compression may cause weakness
Posterior shoulder dislocations occur when a posterior force is exerted on an (abducted / adducted), (internally / externally) rotated shoulder.
adducted, internally rotated shoulder
What X-ray sign is associated with posterior shoulder dislocations?
Light bulb sign
What other joints of the shoulder girdle can dislocate?
Acromioclavicular joint
Sternoclavicular joint
What ligaments may be disrupted by an AC joint dislocation?
Coracoclavicular ligaments
What is the usual mechanism of AC joint dislocation?
Fall onto shoulder
In which directions can the sternoclavicular joints dislocate?
Anteriorly
Posteriorly
What structures can be compressed if the sternoclavicular joint dislocates posteriorly?
Trachea
Oesophagus
Brachiocephalic vein
What symptoms may patients with a posterior SC joint dislocation present with?
Pain
Dyspnoea
Dysphagia
Venous congestion (swelling)
Pure elbow dislocations have a ___ prognosis.
good
What is a Monteggia fracutre?
Fractured ulna with a dislocated radial head @ elbow joint
What is a Galeazzi fracture?
Fractured radius with a dislocated ulna @ DRU joint
What carpal dislocation is commonly missed on imaging and must be treated quickly?
Perilunate dislocation
What finger joint can dislocate and cause deformity?
PIP joint
Describe
a) Swan neck
b) Boutonniere’s deformities?
a) Swan neck - DIP flexion, PIP hyperextension
b) Boutonniere’s - DIP hyperextension, PIP flexion
What aspect of the pelvis can fracture in a hip dislocation?
Posterior wall of the acetabulum
What is the big risk of hip dislocation?
AVN of femoral head
Which nerve can be damaged by hip dislocation?
Sciatic nerve
The hip joint usually dislocates (anteriorly / posteriorly).
posteriorly
What joint arthroplasty is known to dislocate?
THRs
How are hip dislocations treated?
Reduced
Fixed
Physio for early mobility
What is a common knee dislocation in adolescents?
Patellar dislocation
In which direction does the patella usually dislocate?
Laterally
If a bone breaks during a knee/patellar dislocation, what will occur?
Lipohaemarthrosis
bloody fluid in the knee causing effusion and severe pain
Patellar dislocations commonly ___.
recur
What can be compromised in a full blown knee dislocation?
Popliteal artery
Common fibular nerve
Virtually all of the ligaments
What complication, caused by swelling, may occur following a knee dislocation?
Compartment syndrome
How are knee dislocations treated?
Reduce
Fix
+/- revascularisation, ligament reconstruction
Which tarsal bone is at high risk of AVN?
Talus
What is a fracture-dislocation of the TMT joint called?
Lisfranc fracture-dislocation
