THR Acetabular Fracture
Incidence
Increased incidence with press-fit component
- especially if under ream
Prevention
Don't under-ream >1mm
In osteopenic bone
- line to line reaming
- i.e. ream to outer diameter of cup
This also avoids leaving gaps at floor
- very common if under-ream by 2mm
Management Intra-operatively
Intra-operative undisplaced fracture + Stable cup
- 2-4 screws through cup
- TWB 2-3 months
Intraoperative displaced fracture
- remove cup
- plate posterior column if factured
- screw fixation anterior column
- additional screws in cup
- +/- antiprotrusio ring
- TWB 2-3 months
Diagnosis Post operatively
Can be difficult to diagnose & image
- if unexplained groin pain post-op & press-fit cup
- look for fracture with multiple oblique views etc
- CT
- may see callous formation
Post-operative early
1. Non or minimally displaced
- recognised immediate post-op
- TWB 3 months
2. Displaced fracture unstable
- ORIF & revise cup
Post-operative late
Peterson & Lewallen JBJS Aug 1996
Type 1
- cup clinically & radiologically stable
- no treatment
Type 2
- cup unstable
- revise as above
THR Femoral Fracture
Incidence
Increased incidence with press-fit components
- act like splitting wedge
Fracture may occur during
1. Dislocation
2. Reaming or broaching
3. Impaction of component
4. R/O cement or old components
Prevention
During dislocation
Beware in elderly, osteoporotic patient and in revision
- adequate exposure
- only 1 person manipulate femur
If difficult dislocation
- complete ST release
- removal of acetabular osteophytes
- ankylosed joint or protrusio, division of neck in situ & piecemeal removal of femoral head
During femoral preparation
Pre-op templating of component size
- use of reamers before broaching to remove endosteal bone
- gentle broaching with pause if failing to advance
- sufficient broaching for easy prosthesis insertion
Avoid creation of stress risers i.e. cracks, defects, windows
If cracks or defects created
- bypass with implant by 2-3 cortical diameters distally
- minimise cement extravasation as prevents healing of defect
- use cerclage wires to prevent propogation of fracture
During component insertion
- gentle impaction with pause if failing to advance
- uncemented components often 1 - 2 mm proud of equivalent sized broach
Management
Vertical split not beyond LT
- cerclage wire
Vertical split beyond LT
- cerclage wires
- longer stem
Perforation of shaft
- bypass defect
- fixate with plate