Musculoskeletal X-ray - General principles
Systematic approach

Systematic checklist

  • Patient and image details
  • Bone and joint alignment
  • Joint spacing
  • Cortical outline
  • Bone texture
  • Soft tissues

Although the system for viewing X-rays of bones and joints varies depending on the anatomy being examined, there are some broad principles which can be applied in a number of situations.

A systematic approach involves checking alignment of bone structures, joint spacing, integrity of bone cortex, medullary bone texture, and for abnormalities of any visible surrounding soft tissue structures.

Patient and image details

Start by checking you are looking at the correct image. The patient's details should be checked and the date and time of the X-ray noted. The skeletal system is symmetrical, so it is particularly important to be sure you are looking at the correct side.

Bone and joint alignment

Loss of alignment may be due to a bone fracture or a joint dislocation. Both are associated with soft tissue injury that may not be directly visualised.

Bone and joint alignment

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Alignment

  • Loss of bone alignment at the middle toe metatarsophalangeal joint due to dislocation
  • Alignment and joint spacing elsewhere is normal

Clinical information

  • Trauma to forefoot
  • Clinically evident dislocation
  • X-ray performed to exclude underlying fracture

Joint spacing

Joint spacing may be narrowed due to cartilage loss or widened due to dislocation/dissociation.

Joint spacing

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Joint spacing

  • Loss of joint space indicating cartilage loss at the first metatarsophalangeal joint - more pronounced medially (arrowheads) and relatively spared laterally (arrows)

Clinical information

  • Longstanding forefoot pain

Diagnosis

  • Osteoarthritis of the 1st metatarsophalangeal joint
  • Note also the large osteophytes - a sign of osteoarthritis

Cortical outline

Careful scrutiny of the bone cortex is required because a check that is too brief will lead to incorrect or incomplete diagnosis.

In the context of trauma the clinical features of a significant injury may be masked by other injuries. Remember to be systematic, and if you spot one abnormality, do not stop until you are sure you have focussed on all areas of the anatomy shown.

Cortical outline

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Cortical outline

  • Check the cortical outline (white lines) of ALL bones visible on every X-ray available
  • Check for any breach in this outline (red line !)
  • Do not stop when you find one abnormality - keep going until your eyes have covered all bones

Clinical information

  • Punched brick wall when drunk

Diagnosis

  • Fractured ring finger metacarpal bone - a so called 'boxer's fracture'

Bone texture

In some bones a fine matrix of fine white lines (trabeculae) is seen. Occasionally bone injury or disease will result in abnormality of this texture.

Bone texture example - Proximal femur

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Bone texture example - Proximal femur

  • Well defined trabecular pattern visible forming the femoral neck architecture
  • Distortion of this trabecular pattern may make an abnormality more conspicuous

Soft tissues

Scrutinising the soft tissues can often provide helpful information.

Not uncommonly an abnormality of soft tissues is more obvious than a bone injury, or may even imply a bone injury that is not visible at all.

Soft tissue abnormality example

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Soft tissue abnormality example

  • Joint effusion containing fat and blood (lipohaemarthrosis) that has leaked from bone following trauma
  • Visible fracture line - much less conspicuous than the lipohaemarthrosis

Clinical information

  • Severe knee pain following a fall from height

Diagnosis

  • Tibial plateau fracture