dislocation

Epidemiology

6 /100 000

- second most common dislocation after shoulder

Mechanism

FOOSH

Goal

Subluxation & dislocation

Diagnosis

Pisotriquetral view

- forearm positioned 30° supinated off the neutral position

- loss of symmetry between the pisiform and triquetrum is required for the diagnosis

- carpal tunnel view may be helpful in further assessment of the joint

Osteoarthritis

Clinical

More common problem

Deformity

Ulna drift & volar dislocation

Causes of MCPJ Deformity

Ulna Drift / Ulna Dislocation

1.  Physiological

Definition

Patients usually complain of subluxation rather than dislocation

- rarely requires reduction

Different entity to acute posterior dislocation usually

Epidemiology

Rare

Aetiology

1.  Ligamentous laxity > 50%

- commonly associated with MDI

- posterior only 20%

- posterior & inferior 20%

Epidemiology

Rare 

- 2% of acute dislocations

Often missed

- < 1/ 52 25%

- < 6/52 25%

- < 6/12 25%

- > 6/12 25%

Aetiology

Definition

A GH dislocation which has been missed for a significant period of time

- time period is arbitary

- > 3-6 weeks

Pathology

Humerus soft and osteoporotic

Significant soft tissue contractures

1.  Anterior / subcoracoid dislocation

Beware

- scarring to NV structures

- RC tears including SSC, especially > 40

Epidemiology

Most common form of shoulder instability

- young males 

- M:F = 2:1

Aetiology

Indirect ER and abduction moment on arm

- disruption of anterior stabilisers

History

Initial injury

- severe pain in shoulder

Anatomy

Synovial joint with hyaline cartilage

Has fibrocartilage intra-articular disc

- complete or incomplete

- usually degeneration by 4th decade

Clavicle may lie superior to acromion in normal population

Acromioclavicular Ligaments

Incidence

2-3% of cases 

- doubles with infrequent operator

- second most common reason for revision after loosening

Australian Joint Registry

- dislocation accounts for 14.8% of revisions

Positions

Posterior dislocation

- hip flexed, adducted, IR