Basic Science

Question 1

Name all the benign bone tumours.

Answer 1

Osteochondroma, enchondroma, simple bone cyst, aneurysmal bone cyst, giant cell tumour, fibrous dysplasia, osteoid osteoma.

Question 2

What is an osteochondroma?

Answer 2

Bony outgrowth on external surface with cartilaginous cap.

Question 3

What are possible problems associated with osteochondroma?

Answer 3

Very small risk of malignant transformation and can produce local pain.

Question 4

What is an enchondroma?

Answer 4

An intramedullary and usually metaphyseal cartilaginous tumour caused by failure of normal enchondral ossification at the growth plate.

Question 5

What are the problems associated with enchondroma?

Answer 5

Usually asymptomatic but can weaken the bone resulting in pathological fracture.

Question 6

How may an enchondroma causing problems be treated?

Answer 6

Scraped out (curettage) and filled with bone graft to strengthen the bone.

Question 7

What are simple bone cysts and how are they caused?

Answer 7

Single cavity benign fluid filled cyst in bone. Probably a growth defect from the physis and are therefore metaphyseal in long bones.

Question 8

What are aneurysmal bone cysts are how are they caused?

Answer 8

Lots of chambers which are filled with blood or serum. Arteriovenous malformation.

Question 9

What problems can aneurysmal bone cysts cause and how are they treated?

Answer 9

Lesions locally aggressive causing cortical expansion and destruction and is usually painful, also risk of pathological fracture. Again curettage and grafting/bone cement.

Question 10

What problems can giant cell tumours cause?

Answer 10

Locally destructive destroying cortex, they are painful and may cause pathological fracture.

Question 11

Where can giant cell tumours metastasise and are they benign?

Answer 11

5% can metastasise to the lung, they are benign.

Question 12

What is the treatment for giant cell tumours?

Answer 12

Intralesional excision with use of phenol, bone cement or liquid nitrogen to destroy remaining tumour material and reduce the risk of recurrence. Very aggressive lesions with cortical destruction may need joint replacement.

Question 13

What is fibrous dysplasia and when does it usually occur?

Answer 13

Genetic mutation results in lesions of fibrous tissue and immature bone, usually occurs in adolescence.

Question 14

What is the treatment for fibrous dysplasia?

Answer 14

Bisphosphonates to reduce pain, pathological fractures stabilised with internal fixation and cortical bone grafts to improve strength (simple intralesional excision alone has very high recurrence rate).

Question 15

What is an osteoid osteoma and when does it commonly occur?

Answer 15

A small nidus of immature bone surrounded by an intense sclerotic halo. Most commonly occur in adolescence.

Question 16

What is the prominent clinical feature of osteoid osteoma?

Answer 16

Constant pain, worse at night due to intense inflammatory response.

Question 17

What is the treatment for osteoid osteoma?

Answer 17

May resolve spontaneously over time, but may required CT guided radiofrequency ablation or en bloc excision.

Question 18

What is the symptom of metastatic cancer which has spread to bone?

Answer 18

Constant pain which may be severe and usually worse at night.

Question 19

What aggressive and destructive signs do primary bone tumours show on X-ray?

Answer 19

Cortical destruction, periosteal reaction (raised periosteum production new bone), new bone formation (sclerosis as well as lysis from destruction) and extension into surrounding soft tissue envelope.

Question 20

In order of frequency, where does osteosarcoma usually affect?

Answer 20

Knee, proximal femur, proximal humerus and pelvis.

Question 21

What are all the malignant bone tumours?

Answer 21

Osteosarcoma, chrondosarcoma, fibrosarcoma, malignant fibrous histiocytoma, Ewing’s sarcoma.

Question 22

What primary bone tumour has the worst prognosis?

Answer 22

Ewing’s sarcoma.

Question 23

What tumours metastasise to bone in order of frequency?

Answer 23

Breast, prostate, lung, renal cell, thyroid.

Question 24

What is the similar end result of osteochondritis and avascular necrosis (AVN)?

Answer 24

Area of bone undergoes localised necrosis as a result of ischaemia from a reduction in blood supply.

Question 25

What sites are particularly prone to AVN?

Answer 25

Femoral neck, proximal humerus, waist of scaphoid and talar neck.

Question 26

What is the treament of AVN?

Answer 26

Depends on stage, if early drilling can be performed to decompress bone, if articular surface collapses then joint replacement is usually required.