Sacral Fracture

May 1, 2021 | By : OrthoFixar | Trauma


Sacral Fracture is usually a mistreated fracture that results from high energy trauma in young patient, it’s commonly associated with pelvic ring fractures in about (30-45 %).

It also may be associated with neurological complications in about 25% of cases.

See Also: Pelvic Fractures

Sacral Anatomy

  • The sacrum is formed by fusion of 5 sacral vertebrae.
  • Proximally it articulates with the 5th lumbar vertebra, while distally it articulates with the coccyx.
  • Laterally, it articulates with the ilium at sacroiliac joints (SI).
  • Four pairs of pelvic sacral foramina located both anteriorly and posteriorly transmit respective ventral and dorsal branches of the upper four sacral nerves (S1-S4) , while L5 nerve root runs on top of sacral ala.

Sacral Fracture Classification

Sacral Fracture is classified based on fracture location relative to foramen.

Denis classification of Sacral Fracture:

TypeCharactaristicsNerve Injury
Type IFractures occur lateral to the neural foramina through the sacral ala.Rare (5%)
Type IIFractures are transforaminal, it may be Stable / unstable (increased risk of nonunion).
Type IIIFractures occur medial or central to the neural foraminaHigh (60%)
Denis classification of Sacral Fracture

Transverse fractures of the sacrum are classified as type III injuries because they involve the spinal canal and often are H or U shaped (so-called jumper’s fracture because of their association with falls from heights).

See Also: Subtrochanteric femur fracture’s most common deformity after antegrade nailing

Clinical Evaluation

  • History of high energy trauma.
  • Pelvic pain.
  • The examiner should do a full neurovascular examination and assess for pelvic ring fracture.

Sacral Fracture Radiology

  • Recommended Views include AP pelvis view, inlet view, outlet view, and lateral view.
  • CT (usually required).
  • MRI when neurological injury is suspected.

Sacral Fracture Treatment

Nonoperative Treatment

  • Indicated for stable and minimally displaced sacral fractures.

Nonoperative treatment of Sacral fractures include:

  1. Weight bearing as tolerated for incomplete fractures in which the ilium is contiguous with the intact sacrum (e.g., anterior impaction fractures from lateral compression mechanism or isolated sacral alar fractures).
  2. Touch-toe weight bearing for complete fractures.

Operative Treatment

  • Operative treatment is indicated for displaced fractures (>1 cm).

Operative treatment of Sacral fractures include:

  1. Percutaneous iliosacral screws:
    • Before surgery, appropriate fluoroscopic visualization of anatomic landmarks should be made .
    • The pelvic outlet radiograph allows optimal visualization of the S1 neural foramina to avoid injury.
    • The lateral sacral view identifies the sacral alar slope and minimizes risk to the L5 nerve root.
    • High incidence of sacral dysmorphism (20%-44%): Sacralization of L5 or lumbarization of S1.
    • Risk of anterior screw penetration causing neurologic injury is much higher with anterosuperior sacral concavity.
  2. Posterior plating.
  3. Transiliac sacral bars.
  4. Open foraminal decompression considered for neurologic injury associated with zone II fracture.

Complications

Complications of Sacral fractures treatment include:

  1. Neurologic injury:
    • Highest incidence with displaced zone II fractures.
    • L5 nerve root usually involved with zone II fractures.
    • Cauda equina syndrome can be associated with zone III injuries.
  2. Chronic low back pain.
  3. Malunion.

Sacral Dysmorphism:

  • Sacral dysmorphism is seen as a complication of percutaneous iliosacral screws treatment, where either Sacralization of L5 or lumbarization of S1 is happened.
  • The incidence is 20%-44%.

Radiographic signs of sacral dysmorphism best seen on outlet view:

  1. Prominent mammillary processes.
  2. Laterally downsloping sacral ala.
  3. Residual vestigial disc space between S1 and S2.
  4. Top of iliac wing at level of L5/S1 instead of at L4/5.
  5. Noncircular S1 anterior neural tunnel.

Radiographic signs of sacral dysmorphism best seen on axial CT scan:

  1. Peaked or prow-shaped sacral promontory.
  2. Tongue-in-groove sacroiliac articulation.
  3. Oblique and narrow S1 sacral ala.
  4. Wider S2 alar channel.

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