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
- 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:
|Type I||Fractures occur lateral to the neural foramina through the sacral ala.||Rare (5%)|
|Type II||Fractures are transforaminal, it may be Stable / unstable (increased risk of nonunion).|
|Type III||Fractures occur medial or central to the neural foramina||High (60%)|
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).
- 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
- Indicated for stable and minimally displaced sacral fractures.
Nonoperative treatment of Sacral fractures include:
- 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).
- Touch-toe weight bearing for complete fractures.
- Operative treatment is indicated for displaced fractures (>1 cm).
Operative treatment of Sacral fractures include:
- 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.
- Posterior plating.
- Transiliac sacral bars.
- Open foraminal decompression considered for neurologic injury associated with zone II fracture.
Complications of Sacral fractures treatment include:
- 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.
- Chronic low back pain.
- 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:
- Prominent mammillary processes.
- Laterally downsloping sacral ala.
- Residual vestigial disc space between S1 and S2.
- Top of iliac wing at level of L5/S1 instead of at L4/5.
- Noncircular S1 anterior neural tunnel.
Radiographic signs of sacral dysmorphism best seen on axial CT scan:
- Peaked or prow-shaped sacral promontory.
- Tongue-in-groove sacroiliac articulation.
- Oblique and narrow S1 sacral ala.
- Wider S2 alar channel.