Bone Injuries

Question 1

Why bones fracture

Answer 1

If the stress on the bone exceeds the strength of the material

• excessive forces
• weak material
• cumulative damage due to to repetitive loading

Question 2

Types of fracture

Answer 2

Transverse

Spiral

Comminated

Avulsed

Impacted

Greenstick

Compression

Question 3

Excessive stress

Answer 3

Stress = force / cross-sectional area

Caused by

• large external force
• inappropriate dimensions

Question 4

Plain X-ray

Answer 4

2D radiographic imaging

High spatial resolution

Required maneuvering of patient

Simple, available and affordable

Low radiation dose

Question 5

Computerised Tomography (CT)

Answer 5

3D radiographic imaging

Very high resolution of bone

Fast - 20s for whole body scan

Moderately expensive

High radiation dose - 200x that of chest X-ray

Question 6

Bone repair

Answer 6

Repair after failure

Haematoma leads to clot formation

Cartilage fills gap which is ossified to form woven bone

Callous then remodels over time

Question 7

Osteoporosis

Answer 7

Common bone disease in post-menopausal women

Reduction in oestrogen levels disrupt bone remodelling

Leads to reduction in trabecular bone

Reduction in bone mineral density

Increased risk of fracture

Bone mineral density monitoring programme using Dual Energy X-Ray Absorptiometry (DEXA)

Question 8

Stress fractures

Answer 8

Occur when the remodelling process cannot keep up with the damage

Dependent upon the magnitude of load and number of cycles

Most common in metatarsals and tibia

Question 9

Extrinsic risk factors for stress fractures

Answer 9

Change in training

Sudden increase in load

Change in equipment

Question 10

Intrinsic risk factors for stress fractures

Answer 10

Small bone geometry

Relative Energy Deficiency Syndrome

High loading rate due to technique

Question 11

Stress fractures - Bone Scan (Nuclear Medicine)

Answer 11

Patient injected with radioactive tracking marker - Technetium 99 bound to diphosphonate

Identifies areas of high remodelling

Low spatial resolution but high sensitivity

Usually followed by more specific imaging

Available in most hospitals, moderately expensive

High(ish) radiation dose

Question 12

Developing Bone Injuries

Answer 12

Osgood Schlatter’s

Sever’s Disease

Most common in 10-15 year olds

Repetitive tension on rapidly changing growth plate