Arthroplasty Flashcards
Name three types of hip prosthesis
unipolar hemiarthroplasty, bipolar hemiarthroplasty, total hip arthroplasty
Complication associated with bipolar hemiathroplasty:
osteolysis
Normal angle of inclination in THA
Angle of inclination in THA: 30-55 deg
Normal angle of anteversion in hip replacement
About 15 deg
What is the indication for a hip hemiarthroplasty?
subcapital neck fractures that are displaced and at high risk of femoral head avascular necrosis (Garden III and IV fractures)
Normal positioning of the femoral component in THA
Parallel to the femoral shaft or in slight valgus
How many mm of subsidence of the prothesis is normal?
2mm of subsidence
What alignment of the femoral component increases the risk of periprosthetic fracture?
Slight varus alignment increases the risk of stem migration which can result in periprosthetic fracture.
_____ mm or less radiolucent lines at the bone-cement interface can be normal
2 mm
What is a press fit arthroplasty?
Cementless component which uses secondary osseointegration into the hardware on irregular surfaces of the hardware including:
Ingrowth (beads sintered onto metal surfaces)
Ongrowth hydroxyapatite (HA) - on femoral stem
Normal radiographic findings in press fit athroplasties
- resorption of medial femoral cortex (stress shielding)
- thin lucent rim with sclerotic margin about metal (< 2mm) - represents bone ingrowth into hydroxyapatite or microbeads
- endosteal sclerosis
- prosthetic subsidence (<10 mm)
- periosteal reaction and cortical thickening
- does not progress after 9-12 mo
Name the components of a total hip arthroplasty
radiographic appearance of polyethene
radiolucent
