Trauma X-ray - Lower limb

Foot

Fractures and dislocations of the forefoot (metatarsals and phalanges) are usually straightforward to identify, so long as the potentially injured bone is fully visible in 2 planes. The contour of the bone cortex of all bones must be checked carefully.

Standard views

Dorsal-Plantar (DP) and Oblique - are standard projections of the forefoot. If only a phalangeal fracture is suspected then DP and oblique views of the toe(s) can be acquired. Lateral views can also be helpful.

Key points

  • Carefully check the cortical edge of all bones on all views available
  • Always check for alignment of bones at the mid-forefoot junction (tarsometatarsal joints)
  • Injury to the Lisfranc ligament may not be visible on initial X-ray - follow up may be necessary
  • Metatarsal stress fractures are subtle and may not be visible on the initial X-ray
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Foot X-ray anatomy - DP and Oblique views

  • Hindfoot = Calcaneus + Talus
  • Midfoot = Navicular + Cuboid + Cuneiforms
  • Forefoot = Metatarsals + Phalanges
  • 1 = Hind-midfoot junction
  • 2 = Mid-forefoot junction = Tarsometatarsal joints (TMTJs)
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Foot X-ray anatomy - DP and Oblique views

  • Metatarsals and phalanges of the toes are numbered 1 to 5
  • 1 = Big toe
  • 5 = Little toe
  • MC = Medial Cuneiform
  • IC = Intermediate Cuneiform
  • LC = Lateral Cuneiform
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Forefoot X-ray anatomy - Joints

  • MTPJ = Metatarsophalangeal Joints
  • IPJ = Interphalangeal Joint (of big toe only)
  • PIPJ = Proximal Interphalangeal Joints
  • DIPJ = Distal Interphalangeal Joints
  • Note the medial side sesamoid is 'bipartite' (in 2 parts) - this is a common normal variant - not a fracture

Foot ligament anatomy

When checking any post-traumatic foot X-ray it is crucial to assess alignment of the bones at the joints. Loss of joint alignment can represent severe injury, even in the absence of a fracture.

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Forefoot ligament anatomy - Normal

  • DP - Normal alignment of the 2nd Metatarsal with the Intermediate Cuneiform
  • Oblique - Normal alignment of the 3rd Metatarsal with the Lateral Cuneiform
  • Position of the Lisfranc Ligament shown

Lisfranc injury

The 'Lisfranc' ligament stabilises the mid-forefoot junction. Loss of alignment of the 2nd metatarsal base with the intermediate cuneiform indicates injury to this important ligament.

Every post-traumatic foot X-ray must be checked for loss of alignment at the midfoot-forefoot junction (tarsometatarsal joints).

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Lisfranc injury - DP

  • Second metatarsal displaced from the intermediate cuneiform
  • No fracture is visible but this is a severe injury which is debilitating if untreated
  • NOTE: Lisfranc ligament injury can be subtle and does not always result in displacement - If there is a clinically suspected ligament injury then clinical and radiological follow-up must be arranged

Metatarsal fractures

Metatarsal fractures are usually easily recognised, but are often only visible on one view.

Fractures of the 5th metatarsal base are a common injury. The normal 5th metatarsal apophysis should not be mistaken for a fracture.

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Metatarsal shaft fracture

  • Oblique fracture of the 5th Metatarsal shaft
  • Fracture more clearly visible on the oblique image
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5th metatarsal base fracture

  • Left image - The fracture line passes transversely across the bone
  • Right image - A normal unfused 5th metatarsal base apophysis is aligned more longitudinally along the bone

Metatarsal stress fractures

Stress fractures of the metatarsals are common in athletically active individuals. These may not be visible on initial X-rays but follow up images show periosteal stress reaction. This has the appearance of fusiform bone expansion.

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Metatarsal stress fracture

  • Subtle periosteal stress reaction of the 2nd metatarsal
  • History of chronic pain worsened by activity
  • Note: Stress fractures are not always visible on the initial X-ray - if suspected repeat X-ray or MRI may be required

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