Musculoskeletal radiograph interpretation – generic approach

Interpretation > Imaging

Introduction

• Patient: name, DOB, hospital number, age, sex
• Previous films
• Other orientations (need AP and another view – usually lateral)

Radiograph details

• Date
• Type (AP, lateral, other view)
• Area of body (including left/right)
• Adequacy
  • Area: ideally need joint above and below
  • Rotation
  • Penetration (exposure)

Interpretation (ABCS)

Briefly mention obvious abnormalities first.

Alignment

• Joints and bones – look for dislocation or subluxation

Bones

• Trace around cortex looking for fractures – see notes on describing fractures below
• Bone fragments
• Texture of bone between cortex

Cartilage

• Joint spaces
• Disruption of joint contours
• Signs of osteo-/rheumatoid/psoriatic arthritis, gout/pseudogout

Soft tissues

• Disruption
• Swelling
• Foreign bodies or calcification

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Describing fractures 

System for describing a fracture (SOD)

 Site

• Bone
• Intra-/extra-articular
• Position (proximal/middle/distal third)

Obliquity

• Completeness (complete, incomplete)
• Direction (transverse, oblique, spiral)
• Skin penetration (open, closed)
• Condition of bone (comminuted, segmental, multiple, impacted)

Displacement

• Translation (% of bone diameter) – anterior/posterior or medial/lateral
• Angulation (˚) – anterior/posterior or medial/lateral
• Rotation (˚)
• Length distraction/shortening 

For example: ‘There is an extra-articular fracture of the distal third of the right tibia. It is a complete transverse fracture. The fracture is closed. It is non-displaced.’

Glossary of terms

Completeness 

Complete	Bone broken along the whole of its width
Incomplete	Bone cracked but ends not separated

Direction

Transverse	Straight break at a right-angle to the long axis of the bone
Spiral	Corkscrew type fracture due to rotation injury
Oblique	Straight break through a bone but at an angle – rare

Surrounding structural damage

Simple	Isolated bone damage, i.e. no significant soft tissue damage
Complex	Significant soft tissue damage
Closed	Skin is intact
Open/compound	Broken bone protrudes through the skin

Condition of bone

Stable	Likely to stay in a sound position during healing
Unstable	Likely to change position
Comminuted	More than two detached bone fragments
Segmental	Multiple complete fractures creating an isolated bone fragment
Multifragmentary	Several fracture lines or fragments
Impacted	Break ends are compressed together
Stress	Small crack in a bone
Greenstick	Incomplete fracture of one side of the bone resulting in bending of the bone – usually in children

Common joint pathology

• Osteoarthritis (LOSS)
  • Loss of joint space
  • Osteophytes
  • Subchondral cysts
  • Subchondral sclerosis
• Rheumatoid arthritis
  • Loss of joint space
  • Periarticular osteopenia
  • Juxta-articular (marginal) erosions – classic
  • Soft tissue swelling
• Psoriatic arthritis
  • Central erosions (→ ‘pencil in cup’ appearance)
• Gout
  • Punched out lesions in bone (periarticular tophi)
• Pseudogout
  • Chondrocalcinosis

Common radiographs you may see

Shoulder

• Anterior dislocation of glenohumeral joint: seen on AP view as humeral head lying directly below coracoid process
• Posterior dislocation of glenohumeral joint (rare, but sometimes occurs during epileptic fit): humeral head looks like a lightbulb on AP view; seen clearly on apical oblique and scapula Y views, where humeral head is posterior to glenoid
• Proximal humeral fracture
• Clavicle fracture: occurs due to fall onto shoulder/out-stretched hand or direct trauma
• Acromioclavicular joint dislocation/subluxation

Wrist

• Distal radius fracture
  • Colles’ fracture: distal radius fracture with dorsal angulation
  • Smith’s fracture: distal radius fracture with volar angulation
  • Barton’s fracture: intra-articular distal radius fracture
• Scaphoid fracture: scaphoid views should be requested if suspected (clinical signs: 1. anatomical snuffbox tenderness, 2. scaphoid tubercle tenderness, 3. thumb telescoping tenderness). However, fractures are often not visible on X-rays until 10 days after injury. If there is clinical suspicion, treat as a fracture and repeat X-ray in 10 days. Scaphoid fractures are important because of the risk of avascular necrosis due to retrograde blood supply.

Pelvis and hip

• Neck of femur fracture: elderly patient after fall; may be a white line (impacted) or a black line (displaced); intracapsular fractures carry risk of avascular necrosis
• Pubic ramus fracture: elderly patient after fall
• Femoral head dislocation: occurs commonly after total hip replacement and in major trauma
• Children and adolescents with hip pain
  • Perthes disease: 5-10 years; signified by increased density and decreased size of epiphysis
  • Slipped upper femoral epiphysis (SUFE): 10-15 years; seen best on lateral radiograph

Want to find out how 99% of people passed their exams?

Test yourself with some radiographs

This patient presented with a fall and hip pain. Click the image to enlarge. Present the radiograph systematically and then answer the questions below.

This patient presented with a fall and had a swollen wrist. Click the image to enlarge. Present the radiograph systematically and then answer the questions below.

This patient presented with a fall and had a painful shoulder. Click the image to enlarge. Present the radiograph systematically and then answer the questions below.

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