Orthopaedics

Question 1

Name some stressors of the musculoskeletal system. (4)

Answer 1

Trauma - sports injuries, RTA’s, overuse
Infection (bone and joint)
Altered metabolism (age or disease related)
Neurological (muscle spasticity or paralysis)

Question 2

All joints could be replaced - give some examples.

Answer 2

Upper limb: shoulder / elbow / wrist / hand
Lower limb: hip / knee / ankle
Spine: disc replacements

Question 3

When is joint replacement indicated? (6)

Answer 3

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

Question 4

THR (total hip replacement) is one of most common surgical procedures - how much does it cost globally?

Answer 4

£3 billion

Question 5

There are many different hip replacement designs - explain this.

Answer 5

2010 at least 123 acetabular cups and 146 stems in England and Wales.

Question 6

Is cemented or cementless more expensive?

Which is most common?

Answer 6

Cementless - requires more processing to produce

Cementless

Question 7

Does cemented or cementless have higher revision rates?

Answer 7

Very similar with slightly more for cementless

Question 8

When are cemented replacements done?

Answer 8

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.

Question 9

What is meant by a hybrid replacement?

Answer 9

Cemented stem cementless cup

Question 10

How do cementless replacements work?

Answer 10

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.

Question 11

What are the benefits of cemented replacements? (5)

Answer 11

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

Question 12

What are the benefits of cementless replacements? (2)

Answer 12

Less chance of aseptic loosening

Lower incidence of fat embolism

Question 13

What are the disadvantages of cemented replacements?

Answer 13

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

Question 14

What are the disadvantages of cementless replacements? (2)

Answer 14

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

Question 15

What does cemented fixation use?

Answer 15

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.

Question 16

What soft tissue orthopaedics can be done? (6)

Answer 16

Tendon repair
Tendon transfer
Tendon lengthening
Ligament repair
Ligament replacement
Free muscle transfer

Question 17

When is tendon transfer done?

Answer 17

When you have a nerve palsy and a muscle group isn’t working anymore.

Question 18

When is tendon lengthening done?

Answer 18

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.

Question 19

How can the ACL be reconstructed? (2)

Answer 19

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.

Question 20

What muscles can be used in free muscle transfer?

Answer 20

Gracilis muscle (with skin)
Rectus femoris
Or any muscle that is expendable and relatively superficial

Question 21

What are the three types of poor fracture healing?

Answer 21

Delayed
Mal-union
Non-union

Question 22

What is meant by delayed healing?

Answer 22

Failure to consolidate within 1.5x the normal expected time

Question 23

What is meant by mal-union?

Answer 23

Misalignment of proximal and distal fragments leading to biomechanical deformity

Question 24

What is meant by non-union?

Answer 24

Failure to consolidate within 2x the normal expected time - it can be Atrophic / Hypertrophic depending on blood supply and degree of stability.

Question 25

Distraction osteogenesis - what is this?

Answer 25

I.e. bone lengthening procedures. Progressive correction with use of an external fixator (e.g. Ilizarov technique).

Question 26

What four properties are required of bone grafts?

Answer 26

Osteogenesis
Osteoconduction
Osteoinduction
Osteopromotion

Question 27

What is osteogenesis?

Answer 27

Formation or development of new bone cells contained in graft

Question 28

What is osteoconduction?

Answer 28

Physical effect by which the matrix of the graft forms a scaffold that favours outside cells to penetrate the graft and form new bone

Question 29

What is osteoinduction?

Answer 29

Chemical process by which molecules contained in the graft convert the neighbouring cells into osteoblast

Question 30

What is osteopromotion?

Answer 30

When the grafted material enhances osteoinduction

Question 31

Orthopaedic Physiotherapy specialises in…?

Answer 31

Treating patients undergoing planned surgery or those who are admitted to hospital due to a traumatic accident or incident.