Pelvic Radiograph

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AP pelvic radiograph

A pelvis x-ray, also known as a pelvis series or pelvis radiograph, is a single x-ray of the pelvis to include the iliac crests and pubic symphysis. It allows assessment of general pelvic pathology, the sacrum, some of the lower lumbar vertebra and the proximal femora. The pelvis series is comprised of an anteroposterior (AP) with additional projections based on indications and pathology.

Indications

  • pelvic trauma
  • suspicion of pelvic injury
  • assessment of hip pain (consider hip series)

Procedure

  • AP radiograph, usually supine
  • includes the iliac crests, pubic symphysis and both proximal femora

Additional Projections

  • Hip x-ray
    • Pelvic series + lateral/oblique view of the hip
  • Inlet and outlet view
    • utilised for investigating narrowing or widening of the pelvic rim.
    • can be used to assess anterior-posterior displacement of pubic rami fractures
  • Judet views
    • for evaluation of the superior, medial, lateral, and posterior surfaces of the acetabulum
  • Flamingo view
    • evaluation of suspected pubic symphysis instability

Systematic review

Pelvic anatomy, from theRadiologist
Pelvic radiograph review areas, from theRadiologist

Three rings

  • trace the main pelvic ring and two obturator foramina
  • if a ring is disrupted, think fracture... then look for a second one

Joint spaces

  • the sacroiliac joints should be symmetrical, joint space range 2-4 mm
  • the symphysis pubis joint space should be ≤5 mm
  • if either joint space is widened, think main pelvic ring fracture
  • Look for degeneration, sclerosis, unilateral or bilateral involvement.

Acetabulum

  • trace Letournel lines: iliopectineal line, ilioischial line, acetabular roof, anterior rim, posterior rim, and teardrop
    • iliopectineal line disruption suggests a fracture involving the anterior column
    • ilioischial line disruption suggests a fracture involving the posterior column
    • teardrop displacement suggests an occult acetabular fracture

Sacral foramina

  • the arcuate lines should be smooth and symmetrical
  • If lines angulated, think sacral fracture

Proximal femur

  • the cortex of femoral head, neck, greater, and lesser trochanter should be smooth with normal trabecular pattern on AP and lateral
    • if cortical disruption, trabecular pattern disruption or transverse sclerosis, think fractured proximal femur
  • trace the Shenton line
    • If line disruption, think fractured proximal femur

Pubic Rami

  • Assess for fracture

Avulsion Fractures

  • Assess for fractures at pelvic muscle attachments.

Lower lumbar spine

  • Assess as per normal. Look at pedicles.


End by zooming out for an overview, and focus especially on the iliac bones which is a commonly missed area for pathology

Common Pathology

Proximal femoral fracture

  • typically elderly osteoporotic females
  • fall in elderly or high-energy blunt trauma
Intracapsular
fracture site within the joint capsule, subcapital (most common), transcervical, or basicervical. High risk of disruption of the blood supply to the femoral head. Displaced intracapsular fractures are associated with delayed union, non-union, or avascular necrosis
Extracapsular
fracture line distal to the attachment of the femoroacetabular joint capsule. Intertrochanteric (most common) or subtrochanteric

Pubic ramus fracture

  • 40% of all pelvic fractures
  • isolated fracture of superior or inferior ramus most common stable pelvic injury
  • mechanisms: fall in elderly, exercise-induced stress fractures

Complex pelvic ring fracture

  • fracture at one site often associated with a second
  • a double break represents an unstable injury
  • high energy blunt trauma
  • requires CT evaluation

Acetabular fracture

  • bimodal distribution: young (high energy) and elderly (poor bone quality)
  • impaction of femoral head, lateral compression or axial loading
  • 75% associated with femoral head subluxation/dislocation; frequently comminuted

Head of femur dislocation

  • uncommon
  • 80% posterior
  • high energy blunt trauma
  • associated with posterior rim acetabular fractures

Don’t Miss Pathology

Apophyseal avulsion

  • typically adolescent athletes
  • repeated or sudden muscle contraction
  • ischial tuberosity avulsion (hamstring insertion) most common

Sacral fracture

  • common in pelvic ring fractures
  • mechanisms:
  • fall in elderly
  • high-energy blunt trauma
  • frequently missed
  • 25% associated with neurologic injury

References

Part or all of this article or section is derived from Pelvic radiograph (an approach) by Dr Francis Deng and Dr Jeremy Jones et al., used under CC BY-NC-SA 3.0