Orthopaedics

Question 1

Name 6 indications for elective adult joint replacement [6]

Answer 1

• Degenerative disease (e.g. osteoarthritis)
• Inflammatory disease (e.g. rheumatoid arthritis)
• Trauma (e.g. fracture neck of femur / fracture neck of humerus)
• Tumour (metastatic / osteosarcoma)
• Vascular disease (e.g. Avascular necrosis)
• Revision of previously failed / worn out joint replacement

Question 2

Name three main types of total hip replacement (THR)

Answer 2

Cemented
Hybrid: cemented stem; cementles cup
Uncemented - more expensive but more common

Lots of designs: UK: 2010 at least 123 acetabular cups; 146 stems

Question 3

Cemented fixations use which material to create fixation? [1]

What is the role of cement in the fixation?

Answer 3

Cemented fixation uses an acrylic polymer: Poly(methyl methacrylate) (PMMA)

Cement simply acts as a filler between the bone and the implant

Question 4

What physiological response occurs as a result of cement fixation insertion? [1]

Answer 4

Highly exothermic response: can burn tissue

Question 5

Cemented THR are more suitable for which patients? [3]
Uncemented THR are more suitable for which patients? [1]

Answer 5

Cemented:
* obese patients
* dysplastic hips
* patients with osteoporosis

Uncemented:
* Younger & active patients

Question 6

Describe the surfarce of uncemented fixation [1]

What complication is more common in uncementated fixation? [1]

Answer 6

Uncemented have rough surface covered with porous or hydroxyapatite covering

Can create intraoperative fractures; hole needed in COME BACK

Question 7

Whats the difference between how long can weight bear between cemented v uncemented? [2]

Answer 7

Cemented can weight bear immediately

Uncemented: wait 4-6 weeks before weigh bearing

Question 8

State 5 newbiomaterials used for replacements [5]

Answer 8

Ceramic on ceramic
Metal on metal
Ceramic in cross-linked polyethylene
Oxinium in cross-linked polyethylene
Metal in cross-linked polyethylene

Question 9

Which type of material causes least infections / best wear rate?

Ceramic on ceramic
Metal on metal
Ceramic in cross-linked polyethylene
Oxinium in cross-linked polyethylene
Metal in cross-linked polyethylene

Answer 9

Ceramic on ceramic

Question 10

Which of the following has the worst wear / break down?

Ceramic on ceramic
Metal on metal
Ceramic in cross-linked polyethylene
Oxinium in cross-linked polyethylene
Metal in cross-linked polyethylene

Answer 10

Metal on metal

Question 11

The sockets are colour coded.
What are each of these made from? [3]

Answer 11

Question 12

The sockets are colour coded.
What are each of these made from? [3]

Answer 12

Question 13

What is a major problem with THR? [1]

Answer 13

Can wear down

Question 14

What is this? [1]

Which joint does it replace [1]

Answer 14

Speedspiral: tightly rolled acellular human collagen: encourages fibroblast to move in

Replaces carpometacarpal phalangeal joint

Question 15

Four reasons why may need spinal decompression surgery? [4]

Answer 15

Spinal stenosis
Damaged IV disc
Fractured vertebrae
Tumours

Question 16

What is spinal fusion? [1]

Answer 16

Where 2 or more vertebrae are joined together with a section of bone to stabilise and strengthen the vertebral column

Question 17

What is a spinal bone graft? [1]

Answer 17

fuse together painful or unstable bones in the spine so that they heal into a single, solid bone.

Question 18

State and describe this process

Answer 18

Vertebroplasty: the injection of bone cement into the vertebral body in order to relieve pain and / or stabilise the fractured vertebra

Question 19

foot drop x

Question 20

Tendon transfer upper limb

Question 21

Describe why may undergo tendon lengthening for the Achilles [1]

What are they two methods? [2]

Answer 21

Plantar flexors are more powerful than dorsiflexors; can get hypertonia of plantar flexors

Surgery can lengthen the achilles:
- Cut a V into the achilles and lengthen
OR
- Cut a Z into achilles and lengthen

Question 22

What are the two methods for ACL reconstruction?

Answer 22

Patella - ligament - tibia

Hamstring: semitendinous and or gracilis tendons

Question 23

What is a free muscle transfer? [1]

Answer 23

Take whole muscle (& overlying skin) and place elsewhere in body

Question 24

Which muscle is commonly used for free muscle transfer? [1]

Expl

Answer 24

Rectus femoris
Place femoral nerve that have detached and link to tibial nerve

Question 25

What are the three types of poor fracture healing? [3]

Answer 25

Delayed Malunion Non-union

Question 26

Explain the different types of poor fracture healing [3]

Answer 26

**Delayed** Failure to consolidate within **1.5x** the normal expected time **Malunion**: Misalignment of proximal and distal fragments leading to biomechanical deformity: * Rotation * Angulation * Shortening * Translation **Non-union** * Failure to consolidate within 2x the normal expected time Can be **Atrophic / Hypertrophic depending on blood supply and degree of stability**

Question 27

What is the difference between atrophic and hypertrophic blood supply in non-union fracture healing? [2]

Answer 27

**Hypertrophic** – there is a blood supply that causes bone growth on either side of the fracture but if there is **adequate insecure fixation the fracture moves and forms a callus that may continually break and reform.** **Atrophic** – no blood supply

Question 28

What are osteotomy [1] and distraction osteogenesis? [1]

Answer 28

**Distraction osteogenesis** (i.e. bone lengthening procedures) * Progressive correction with use of an external fixator (e.g. Ilizarov technique) **Osteotomy** * Re-alignment osteotomy

Question 29

Explain the four different types of bone grafts

Answer 29

**Osteogenesis** * Formation or development of new bone cells contained in graft * The cells are the “seeds” **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 * The scaffolds are the “trellis” **Osteoinduction** * Chemical process by which molecules contained in the graft convert the neighbouring cells into osteoblast * Growth factors are the “fertilizer” **Osteopromotion** * When the grafted material enhances osteoinduction * Trellis and fertilizer, or trellis and seeds

Question 31

Describe the process of aseptic loosening

Question 32

Difference between hybrid and reverse hybrid fixations? [2]

Answer 32

**Hybrid fixation** Femoral component inserted without cement while acetabular is **Reverse hybrid fixation** Acetabular component inserted with cement while femoral isn't

Question 33

Difference between hybrid and reverse hybrid fixations? [2]

Answer 33

**Hybrid fixation** Femoral component inserted without cement while acetabular is **Reverse hybrid fixation** Acetabular component inserted with cement while femoral isn't

Question 34

Tendon transfer for wrist extension (radial nerve palsy)? [2]

Answer 34

**PT (pronator teres)** to **ECRB (extensor carpi radialis brevis)**

Question 35

Tendon transfer for finger MCP extension? (radial nerve palsy)? [2]

Answer 35

**FCU** to **EDC** (extensor digitorum communis)

Question 36

Tendon transfer for thumb extension? [2]

Answer 36

**PL (palmaris longus)** to rerouted **EPL (extensor pollicis longus)**