Summary Sacral fractures are common pelvic ring injuries that are under-diagnosed and often associated with neurologic compromise. Diagnosis can made with pelvis radiographs but frequently require pelvic CT scan for full characterization. Treatment may be nonoperative or operative depending on fracture displacement, associated pelvic ring instability and patient activity demands. Epidemiology Incidence common in pelvic ring injuries (30-45%) Bimodal distribution young adults as a result of high energy trauma elderly as a result of low energy falls Associate injuries 25% are associated with neurologic injury frequently missed login to view 2 more bullets Anatomy Osteology formed by fusion of 5 sacral vertebrae articulates with 5th lumbar vertebra proximally coccyx distally ilium laterally at sacroiliac joints contains 4 foramina which transmit sacral nerves Nerves L5 nerve root runs on top of sacral ala S1-S4 nerve roots are transmitted through the sacral foramina S1 and S2 nerve roots carry higher rate of injury lower sacral nerve roots (S2-S5) function login to view 3 more bullets unilateral preservation of nerves is adequate for bowel and bladder control Biomechanics transmission of load distributed by first sacral segment through iliac wings to the acetabulum Classification Denis classification Denis classification Zone 1 Fracture lateral to foramina Most common (50%) Nerve injury rare (5%). -usually occurs to L5 nerve root Zone 2 Fracture through foramina May be stable vs. unstable Zone 2 fracture with shear component highly unstable Unstable fractures have higher risk of nonunion and poor functional outcome Zone 3 Fracture medial to foramina into the spinal canal Highest rate of neurologic deficit (60%) -bowel, bladder, and sexual dysfunction Transverse sacral fractures higher incidence of nerve dysfunction U-type sacral fractures results from axial loading represent spino-pelvic dissociation high incidence of neurologic complications Presentation History motor vehicle accident or fall from height most common repetitive stress insufficiency fracture in osteoporotic adults Symptoms peripelvic pain Physical exam inspection soft tissue trauma around pelvis should raise concerns for pelvic or sacral fracture palpation test pelvic ring stability by internally and externally rotating iliac wings palpate for subcutaneous fluid mass indicative of lumbosacral fascial degloving (Morel-Lavallee lesion) perform vaginal exam in women to rule-out open injury neurologic exam rectal exam light touch and pinprick sensation along S2-S5 dermatomes perianal wink bulbocavernosus and cremasteric reflexes vascular exam distal pulses login to view 1 more bullet Imaging Radiographs only show 30% of sacral fractures recommended views AP lateral login to view 2 more bullets inlet view login to view 1 more bullet outlet view login to view 1 more bullet findings L4 or L5 transverse process fractures asymmetric foramina anterior pelvic ring disruptions stepladder sign login to view 3 more bullets CT diagnostic study of choice recommend coronal and sagittal reconstruction views MRI recommended when neural compromise is suspected Treatment Nonoperative progressive weight-bearing +/- orthosis indications login to view 2 more bullets Operative surgical fixation indications login to view 4 more bullets surgical fixation with decompression indications login to view 1 more bullet Techniques Percutaneous screw fixation screws may be placed as sacroiliac, trans-sacral or trans-iliac trans-sacral useful for sagittal plane fractures technique screws placed percutaneously under fluoroscopy beware of L5 nerve root avoid overcompression of fracture login to view 1 more bullet screw placement posterior to the ICD ensures safe screw placement login to view 1 more bullet cons may result in loss of fixation or malreduction does not allow for removal of loose bone fragments do not use in osteoporotic bone Posterior tension band plating approach posterior two-incision approach technique may use in addition to iliosacral screws pros allows for direct visualization of fracture cons wound healing complications Iliosacral and lumbopelvic fixation approach posterior approach to lower lumbar spine and sacrum technique pedicle screw fixation in lumbar spine iliac screws parallel to the inclination angle of outer table of ilium longitudinal and transverse rods pros shown to have greatest stiffness when used for an unstable sacral fracture lumbopelvic fixation for spinopelvic dissociation provides adequate stability for mobilization cons invasive Decompression of neural elements technique indirect login to view 1 more bullet direct login to view 1 more bullet Complications Venous thromboembolism often as a result of immobility Iatrogenic nerve injury may result from overcompression of fracture improper hardware placement Malreduction more common with vertically displaced fractures Prognosis Presence of a neurologic deficit is the most important factor in predicting outcome Displacement confers an increased risk of neurologic dysfunction Mistreated fractures may result in lower extremity deficits urinary dysfunction rectal dysfunction sexual dysfunction