Multidirectional Instability
Definition
Instability in at least 2 planes
- postero-inferior
- antero-inferior
- antero-postero-inferior
Epidemiology
Recognised as a common problem
- often misdiagnosed
Most patients athletic
Instability in at least 2 planes
- postero-inferior
- antero-inferior
- antero-postero-inferior
Recognised as a common problem
- often misdiagnosed
Most patients athletic
Indications have narrowed
- due to success of shoulder arthroplasty
1. Chronic infections of GHJ
2. Stabilization in paralytic disorders
3. Post-traumatic brachial plexus palsy
4. Salvage of failed GHJ Arthroplasty
- may need bone graft procedures
5. Arthritic diseases unsuitable for arthroplasty / young patient
Post-traumatic (type III clavicle fractures)
Idiopathic
1. OA with osteophytes
- contribute to impingement

2. Osteolysis with resorption & gross osteoporosis
Lateral : Medial 9:1
4th & 5th decades
- M = F
- 75% dominant arm
50% of regular tennis players
- especially > 2 hrs / week
Insertion pathology / Enthesopathy
Over-extension of the elbow with supination / pronation
Lateral epicondyle
- anconeus from posterior face
- ECRB and EDC from anterior face (CEO)
Chronic instability due to rupture of one or more parts of the lateral ligament
Progressive injury
1. Anterolateral capsule
2. ATFL
3. CFL
Can lead to ankle OA over time
