Atlanto-axial instability
Definition
Loss of ligamentous stability between atlas and axis
Can cause impingement of the spinal cord
Etiology
Loss of ligamentous stability between atlas and axis
Can cause impingement of the spinal cord
Acute dislocation of the atlanto-axial facet joint
Present with acute torticollis
Children
Athletes with increase activity / distance
Women with eating disorders / amenorrhea
Compression / inferior neck
- < 50% protective weight bear
- > 50% emergent ORIF
Tension side / superior neck
- emergent ORIF
Ranges
- up to 4%
Focal pain
- typically anterolateral thigh
- often tender
- corresponds to tip of stem
1. Instability
Types
- early
- late / failed bony ingrowth
Cause
- micromotion at distal stem
Disseminated Intravascular Coagulation
Results from excessive activation of either extrinsic or intrinsic coagulation pathway
- multiple small clots
- consumptive coagulopathy
1. Excessive Extrinsic Activation
Secondary to extensive cellular destruction
- thromboplastins +++ released into circulation
Chronic Regional Pain Syndrome
CRPS 1
Sympathetically mediated pain syndrome
- excessive or exaggerated response of extremity to injury, surgery or disease
Manifested by
- intense or unduly prolonged pain
- vasomotor disturbances
- trophic changes
- delayed functional recovery
CRPS 2
Most common of the bleeding disorders
- 1:100
vWF
- needed for platelet adhesion and platelet-platelet interactions
- also carrier for factor VIII / protects it from rapid breakdown
Gene on chromosome 12
1. Reduced production VWF
1. Loosening
2. Infection
3. Instability
4. Periprosthetic fracture
Biological response to particulate matter
- characterised by periprosthetic osteolysis
- stimulated by wear debris
- debris gains access to any area accessible by fluid
1. Wear
Mechanisms of wear