Facet joint dislocations secondary flexion distraction injury
10%
1. Unifacet subluxation - interspinous process widening
2. Unifacet dislocation - 25% anterolisthesis
3. Bifacet dislocation - 50% anterolisthesis
4. Complete vertebral translation - 100% anterolisthesis
Burst fractures
- injury to anterior and middle columns +/- posterior column
Vertical compression
10% cervical fractures
Most commonly C5/6
Anterior & middle columns fail
- if severe, posterior ligament complex fails
3 facets
1. Posterior facet (STJ)
2. Middle facet (sustenaculum tali)
3. Anterior facet (on distal medial aspect)
Anterior process
- forms calcaneocuboid (CCJ) articulation
Thalamic portion
- under lateral process talus
Tuberosities
Posterior tuberosity
- posterior process / T Achilles attachment
5-15% of posterior dislocations
Posterior hip dislocation
Type I - head fracture below fovea
Undisplaced
- non operative
Displaced
- excise fragment if small
- ORIF fragment if large (can contribute to instability)
Primary malignancy arising from remnants of the notochord
Rare malignant tumour
Middle-aged adults (50-70)
M>F
In midline in axial skeleton
Base of skull 35%
Vertebrae 15%
- especially cervical
Sacrum 50%
Chondroid Metaplasia of synovium affecting large joints
Nodules of hyaline cartilage
- formed in the subsynovial layer of joint capsules
Rare lesion
Most common in 20's and 30's
Sex: M > F (2:1)
Monoarticular
Sartorius
Rectus femoris
Pelvis is a true ring
- any anterior fracture must have a posterior injury as well
- integrity of the posterior sacroiliac complex is key
2 innominate bones + sacrum
Symphysis pubis < 5mm
SI joint 2-4 mm
1. Late presenters
2. Failures of splint in those < age 6/12
1. Adductor tenotomy + closed reduction
- most surgeons will attempt this initially
- risk of AVN wilth forceful reduction / excessive abduction
2. Open Reduction
- for failure of closed reduction
Irradiate a slice of tissue from multiple angles
Measure the output from different sides
Tissues have different densities
- with denser tissue fewer x-rays reach the detectors
Bone 2000
ST 40
Water 0
Fat -100
Air -1000