Joint Position
February 15th, 2021
Overview
Look For
Joint disassociation.- Shoulder - anterior / posterior / inferior
- Finger - interphalageal / metacarpophalangeal
- Elbow - posterior / posterolateral / posteromedial
- Patella - lateral / medial
- Hip - posterior / anterior
- Wrist - lunate / perilunate
Interpretation
- Simple - dislocation without fracture
- Complex - dislocation with fracture of any of the bones involved
Shoulder Dislocation
Look For
- Disassociation of the humeral head from the glenoid.
Interpretation
- Anterior dislocation (95%) - anterior, medial and inferior displacement of the humeral headForced extension + abduction + external rotation, direct trauma from behind
- Posterior dislocation (4%) - posterior displacement of humeral head on axillary viewForced contraction of shoulder muscles
- Inferior dislocation (1%) - inferior displacement of humeral headForced abduction
In the case of anterior dislocation, look for the associated Bankart lesion (detachment of anterior labrum) and Hill-Sachs lesion (impacted posterolateral humeral head fracture).
Elbow Dislocation
Look For
- Dislocation of the elbow joint - most commonly posterior, though may be posterolateral, posteromedial, lateral or medial.
- Fracture of the radial head, olecranon or coronoid process.
Hip Dislocation
Look For
- Disassociation of the femoral head from the acetabulum.
Interpretation
- Posterior dislocation (90%) - posterior, superior and lateral displacement of the femoral headAxial load onto flexed hip (e.g. dashboard injury)
- Anterior dislocation (10%) - anterior displacement, with the femoral head lying either superior (pubic) or inferior (obturator) to the acetabulum.Direct trauma while in abduction and external rotation
Patellar Dislocation
Look For
- Displacement of the patella. Most commonly lateral, though may be medial.
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