Hip Flashcards
Why does pathology in the hip commonly radiate the knee
The obturator nerve supplies both joints
Where can hip pathology present i.e. where can it produce pain
Groin
Buttock pain
Knee pain
What is usually the first sign of hip pathology
Loss of internal rotation
What are the hip abductor muscles
gluteus medius and minimus
What causes a positive Trendelenburg sign
abductor muscle weakness
What is the gold standard material THR
cemented metal stainless steel stem and a high density polyethylene cup
What is the ultimate cause of failure of a THR
loosening of one or both prosthetic components
How long does a THR usually last for
15-20 years
Generally, what is the principal of uncemented THR
the aim is for bone to grow into a roughened porous surface of the stem
What causes the loosening of the materials in THR
Wear particles from the implant cause an inflammatory reaction at the implant-bone interface. The release of inflammatory mediators results in osteoclastic bone resorption
Why were ceramics materials not previously used as the material for THR
They were too brittle, so fatigued too easily
Why are metal-on-metal THR replacements not used
They can lead to a local reaction to the metal debris and cause a “inflammatory pseudotumour”
What are the conservative Mx options for arthritic hip pain
Simple analgesics
Physio
Use of a stick (reduces joint force)
Weight reduction
Early local complications of THR
Infection
Dislocation
Nerve injury (sciatic)
Leg length discrepancy
Early general complications of THR
medical complications from surgery
- MI
- chest infection
- UTI
- blood loss
- hypovolaemia
- DVT & PE
Late local complications of THR
Early loosening
Late infection
Late dislocation
If a primary THR fails, what can be done
it can be re-done - revision hip replacement
Problems with revision hip replacements
bigger and more complex surgery more blood loss twice the complication rates poorer functional outcomes don't last as long as primary replacements
Why are THR in younger patient’s not recommended?
they have a higher risk of requiring revision surgery in later life as they put more demand on prosthetic hip
Causes of hip AVN
idiopathic alcohol abuse steroids hyperlipidaemia thrombophilia
presentation of hip AVN
groin pain
Ix for AVN
MRI
- best for seeing early changes, as these won’t show on xray
patchy sclerosis of weight bearing area of femoral head
lytic zone underneath (formed by granulation tissue attempting repair)
Classic sign of AVN on xray
Hanging rope sign
- caused by the lytic lesion forming underneath the weight bearing part of the femoral head
What is the consequence of undetected AVN
Femoral head collapse, with subsequent secondary OA
