Orthopaedics Flashcards
Name some stressors of the musculoskeletal system. (4)
Trauma - sports injuries, RTA’s, overuse
Infection (bone and joint)
Altered metabolism (age or disease related)
Neurological (muscle spasticity or paralysis)
All joints could be replaced - give some examples.
Upper limb: shoulder / elbow / wrist / hand
Lower limb: hip / knee / ankle
Spine: disc replacements
When is joint replacement indicated? (6)
Degenerative disease (e.g. osteoarthritis)
Inflammatory disease (e.g. rheumatoid arthritis)
Trauma (e.g. fracture neck of femur or of humerus)
Tumour
Vascular disease (e.g. avascular necrosis)
Revision of previous joint replacement
THR (total hip replacement) is one of most common surgical procedures - how much does it cost globally?
£3 billion
There are many different hip replacement designs - explain this.
2010 at least 123 acetabular cups and 146 stems in England and Wales.
Is cemented or cementless more expensive?
Which is most common?
Cementless - requires more processing to produce
Cementless
Does cemented or cementless have higher revision rates?
Very similar with slightly more for cementless
When are cemented replacements done?
Some joints will always require cement
In older patients, those who are physically inactive, and in obese patients, those with osteoporosis or dysplastic hips - these patients don’t have very active bone growth.
What is meant by a hybrid replacement?
Cemented stem cementless cup
How do cementless replacements work?
Use porous-coating (or hydroxyapatite) on outside which allows bone cells to grow into the prostheses (uses body’s bone to hold it in place.
Maximum bone ingrowth is obtained with pore size 100-400 μm. Gap should be <0.5mm.
What are the benefits of cemented replacements? (5)
Less chance of intra-operative fractures
Can weight bear immediately
Better revision rates
Don’t need to be as precise as cementless
Can add antibiotic material to cement to prevent infection
What are the benefits of cementless replacements? (2)
Less chance of aseptic loosening
Lower incidence of fat embolism
What are the disadvantages of cemented replacements?
Can get allergic reaction from cement and gets hot, can burn soft tissue around it.
Cement implant syndrome
Loosening of cemented acetabular components after 10 years
What are the disadvantages of cementless replacements? (2)
Require more care and skill in plantation
Longer recovery period (4-6 weeks non weight bearing)
Can’t be used in bone that isn’t healthy e.g. in osteoporosis
What does cemented fixation use?
Acrylic polymer - Poly(methyl methacrylate) (PMMA)
Both the bone and cement must lock together to make insertion last. The cement simply acts as a filler between the bone and the implant.
What soft tissue orthopaedics can be done? (6)
Tendon repair Tendon transfer Tendon lengthening Ligament repair Ligament replacement Free muscle transfer
When is tendon transfer done?
When you have a nerve palsy and a muscle group isn’t working anymore.
When is tendon lengthening done?
For people who have muscle imbalances e.g. in cerebral palsy.
For example – you can cut the Achilles tendon in Z or Y shape to give it more length.
How can the ACL be reconstructed? (2)
Can take patella, patella ligament and tibia (strip down the middle of the knee) and feed this through the knee to replace the ACL. Heals in quicker (than hamstring tendon), but bigger scar.
Or can take tendon (more elastic fibres in it) e.g. semitendinosus or gracilis tendons and insert it into the knee to replace. Smaller scar.
What muscles can be used in free muscle transfer?
Gracilis muscle (with skin)
Rectus femoris
Or any muscle that is expendable and relatively superficial
What are the three types of poor fracture healing?
Delayed
Mal-union
Non-union
What is meant by delayed healing?
Failure to consolidate within 1.5x the normal expected time
What is meant by mal-union?
Misalignment of proximal and distal fragments leading to biomechanical deformity
What is meant by non-union?
Failure to consolidate within 2x the normal expected time - it can be Atrophic / Hypertrophic depending on blood supply and degree of stability.
Distraction osteogenesis - what is this?
I.e. bone lengthening procedures. Progressive correction with use of an external fixator (e.g. Ilizarov technique).
What four properties are required of bone grafts?
Osteogenesis
Osteoconduction
Osteoinduction
Osteopromotion
What is osteogenesis?
Formation or development of new bone cells contained in graft
What is 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
What is osteoinduction?
Chemical process by which molecules contained in the graft convert the neighbouring cells into osteoblast
What is osteopromotion?
When the grafted material enhances osteoinduction
Orthopaedic Physiotherapy specialises in…?
Treating patients undergoing planned surgery or those who are admitted to hospital due to a traumatic accident or incident.
