19 - Orthopaedics Flashcards
Indications for Joint Replacement
Degenerative disease Inflammatory Disease Trauma Tumour Vascular Disease Revisions
Most common joint replacement
Hip replacement
What is the acrylic polymer used in cemented fixation
Polymethyl methacrylate
PMMA
What is cementing
Using the PMMA as a filler between bone and the implant
Cemented or cementless in an obese, osteoporotic, elderly person
Cemented
Why does cementless take weeks for patient to move?
You need the bone cell to grow into the porous surface
How big should the gap be in cementless
<0.5mm
therefore requires v precise placement
What is a hybrid in cementing
Cemented stem
Cementless cup
What is a reverse hybrid in cementing
Cementless stem
Cemented cup
What is aseptic loosening
Resorption at the bone-cement interface causing it to be loose + wobble
Which material has the least wear rate
Ceramic on ceramic (less than 1um a year)
(then metal on metal
then ceramic + CL polyethylene then oxinum+CL polyethylene )
Which material has the highest wear rate
Metal in cross-linked polyethylene (200um a year)
Why would you perform a spinal decompression surgery
Spinal stenosis
Damaged IV disk
Fractured vertebrae
Tumours
What is a spinal fusion
2+ vertebrae joined together with a section of bone to stabilise and strengthen the vertebral column
When would you do a tendon transfer
if your nerve is also damaged
Mid shaft of humerus fracture
Wrist drop
radial nerve palsy
What can you use pronator teres as
extensor carpi radialis brevis
What can you use flexor carpi ulnaris as
extensor digitorum communis
Most common ligament repair
ACL reconstruction
Delayed fracture healing
Failure to consolidate within 1.5x the normal expected time
Mal-union
Misalignment of proximal and distal fragments leading to biomechanical deformity
Non-union
Non-union - Failure to consolidate within 2x the normal expected time
Osteotomy
Realignment
Distraction osteogenesis
Bone lengthening procedure
Progressive construction with use of an external fixator
Osteogenesis
Development of new bone cells contained in graft
Osteoconduction
Physical effect by which the matrix of the graft forms a scaffold that favours outside cells to penetrate the graft and form new bone
Osteoinduction
Chemical process by which molecules contained in the graft convert the neighbouring cells into osteoblast
Osteopromotion
When the grafted material enhances osteoinduction
Bone substitutes
Xenografts
alloplasts
Human bone grafts
Autografts
Allografts
