Joint dislocation (incl. acromio-clavicular, elbow, shoulder, patella) Flashcards
What is the difference between subluxation vs dislocation?
Dislocation is injury to a joint that causes adjoining bones to no longer touch each other.
Subluxation is a minor or incomplete dislocation in which the joint surfaces still touch but are not in normal relation to each other.
What is the most common mechanism for elbow dislocation?
This is usually produced by a fall on the hand with the elbow partially flexed.
What is the mechanism of injury for acromioclavicular joint subluxation to occur?
Uncommon - usually caused by fall onto the shoulder e.g. in sports
What ligaments are torn in ACJ subluxation?
Superior and inferior AC ligaments
BUT coracoclavicular ligament remains intact
What ligaments are additionally torn in ACJ dislocation?
Superior and inferior AC ligaments
AND coracoclavicular ligament
What is the management and prognosis of ACJ dislocation/subluxation?
Displacement is difficult to position but function is usually good even without full correction. Subluxation will usually persist.
Broad sling +/- strapping over ACJ
Surgical - only if pain persists –> surgical repair or reconstruction of the coracoclavicular ligament e.g. using screw across clavicle or figure of 8 wire. These can then be removed but subluxation may recur.
What are the clinical features of ACJ dislocation/subluxation?
- Prominent outer clavicle
- Swelling
- Restricted shoulder movements
May be missed on XR unless patient holds a weight in hand during the image.
Which system ic used to classify ACJ dislocations?
Rockwood system - 6 types
What is the mangement of patella dislocation?
- Reduction usually achieved by straightening the knee
- Cast or firm bandage - allows the capsule to heal
- Active mobilisation
Medial patellofemoral ligament can also be repaired or constructed.
What is the mechanims of injury in shoulder dislocations?
Fall on arm or shoulder
What are the types of shoulder dislocation and which is most common?
- Anterior dislocation is the most common (95%)
- Posterior
- Inferior
What are the clinical features of shoulder dislocation?
- Anterior dislocation –> flattening of the deltoid muscle –> loss of curved contour of the shoulder which becomes ‘squared off’
- Posterior dislocation –> less obvious, ‘lightbulb sign’ on XR
- Inferior dislocation –> arm lies in a vertical position beside the patients head
- Pain
- Patient supports arm against all movement
- Humeral head may be palpable - below coracoid or in axilla
What is luxatio erecta?
Inferior dislocation
When is the ‘lightbulb sign’ seen?
Posterior dislocation
What is the Y view of the shoulder and why is it useful?
Lateral scapula shoulder aka Y view is part of the standard shoulder series - pertinent projection to assess suspected dislocations, scapula fractures, and degenerative changes. It is also useful in seeing both the coracoid and acromion process in profile.
The “Y” of this view is formed by the scapula’s body, spine, and coracoid process
What is a Hill Sachs lesion?
A defect visible in the humeral head after several dislocations or on the edge of the glenoid on a lateral XR
What is a Bankart lesion?
Lesion where cartilaginous glenoid labrum and capsule is avulsed from the anterior margin of the glenoid
What type of shoulder dislocation is this?
Anterior –> squaring of the shoulder
What are the clinical features of elbow dislocation?
- Swelling
- Elbow held in flexed position
- Ulna displaced backwards on the lower end of the humerus
- Fractures of the radial head or coronoid process
