Hand radiograph (an approach)

Hand radiographs are commonplace in the Emergency Department or the trauma reporting list. 

Systematic review

Choosing a search strategy and utilising it consistently is a helpful method to overcome common errors seen in diagnostic radiology. The order in which you interpret the radiograph is a personal preference. A recommended systematic checklist for reviewing musculoskeletal exams is: soft tissue areas, cortical margins, trabecular patterns, bony alignment, joint congruency, and review areas. Review the entire radiograph, regardless of perceived difficulty. Upon identifying an abnormality, do not cease the review, put it to the side and ensure to complete the checklist.  

Soft tissue

Assess all soft tissue structure for any associated or incidental soft tissue signs 

Metacarpals

Assess the cortex of each metacarpal in turn:

• pay particular attention to the 1st and 5th metacarpals
• metacarpal injuries or those affecting several phalanges may coexist with injuries to other digits
• if cortical disruption of the 5th metacarpal neck, think Boxer fracture
• be wary of fractures involving the joint surface - they are unstable
• if intra-articular cortical disruption of the 1st metacarpal base, think Bennett fracture dislocation or Rolando fracture

Phalanges

Assess the cortex of each phalanx in turn, proximal to distal:

• pay particular attention to phalangeal tufts, shafts and ligamentous insertions
• if lateral or medial bony fragment, think collateral ligament avulsion
• if dorsal bony fragment, think  extensor tendon avulsion 
• if palmar bony fragment, think volar plate avulsion

Alignment

Assess the alignment of the metacarpals and phalanges:

• check each finger from metacarpal to distal phalanx
• malalignment and reduced joint space both point to dislocation
  • carpometacarpal dislocation
  • metacarpophalangeal dislocation
  • interphalangeal dislocation

Joint spaces

Assess the carpal and carpometacarpal joint space:

• 1-2 mm joint space should be seen between the carpals and metacarpals
• look specifically at the base of the 4th and 5th metacarpals
• if the joint space is narrowed, think carpometacarpal dislocation

Assess the interphalangeal joint space:

• metacarpophalangeal, proximal interphalangeal and distal interphalangeal joints should be congruent and there should be a visible joint space

Review the wrist

A hand radiograph contains a PA and oblique view of the distal radius and ulna and the carpus.

• check the wrist as you would for a wrist radiograph (an approach)
  • distal radius
  • carpal alignment
  • carpometacarpal articulation
  • bone cortex

Common pathology

Interphalangeal joint dislocation

• common upper extremity dislocation
• usually a hyperextension injury
• typically dorsal dislocation of PIP joint +/- bony avulsion
• palmar bony fragment indicates avulsion of volar plate
• more: interphalangeal joint dislocation

Mallet finger

• disruption of extensor mechanism at DIP joint leading to tendon injury +/- bony avulsion
• extended finger struck at the tip or crushed
• dorsal bony fragment indicates avulsion of the extensor tendon
• more: Mallet finger

Boxer fracture

• minimally comminuted, transverse fracture of the 5th metacarpal
• 25% of all metacarpal fractures
• usually young male adults
• caused by a direct blow when the fist is clenched
• more: Boxer fracture

Bennett fracture

• unstable intra-articular fracture of the base of 1st metacarpal 
• caused by forceful thumb abduction
• large metacarpal fragment dislocated by a pull of abductor pollicis longus
• small metacarpal fragment remains attached to MCP joint
• more: Bennett fracture

Skier/gamekeeper thumb

• rupture of ulnar collateral ligament of 1^st MCP joint
• there may be an associated bony avulsion
• avulsion fracture occurs at the ulnar corner of the proximal phalanx base
• caused by forceful thumb abduction
• more: Gamekeeper's thumb

Don't miss...

Rolando fracture

• base of 1st metacarpal intra-articular fracture - comminuted (3 fragments) and highly unstable
• axial blow to partially flexed metacarpal
• fracture line typically T or Y-shaped
• more: Rolando fracture

Carpometacarpal dislocation

• rare but significant injury to dominant hands of younger males
• younger male predominance
• often occur after a punch followed by a fall
• reduction of joint space on the AP
• best seen on an oblique study
• more: carpometacarpal dislocation

Enchondroma

• common benign medullary cartilaginous neoplasm
• tend to be seen in young adults
• 50% lesions found in small tubular bones
• complicated by pathological fracture
• more: enchondroma