Treatment of Sacrum Fractures
Most sacral fractures are treated conservatively with pain management and early mobilization, but surgical fixation is mandatory for rotationally or vertically unstable fractures with pelvic ring disruption. 1
Initial Diagnostic Approach
The diagnostic pathway must begin with proper imaging to determine fracture stability, which dictates treatment:
- MRI without IV contrast is the preferred initial imaging modality when radiographs are negative or equivocal, as it provides excellent sensitivity for detecting bone marrow edema and fracture lines that characterize sacral fractures 2, 1
- Radiographs alone miss approximately 35% of sacral fractures and should not be relied upon to exclude the diagnosis 1
- CT without contrast serves as an alternative when MRI is contraindicated or equivocal, though it is less sensitive for early stress injuries 2, 1
- In pregnant patients, MRI without contrast is rated 9/9 (usually appropriate) to avoid fetal radiation exposure 2
Treatment Algorithm Based on Fracture Stability
Conservative Management (Stable Fractures)
Most isolated sacral fractures without pelvic ring disruption can be managed non-operatively with the following approach:
- Pain management should be optimized to facilitate early mobilization and prevent complications of prolonged bed rest 1
- Activity modification with gradual return to full activity as pain resolves is the cornerstone of treatment 1
- Bracing with a lumbosacral orthosis is optional and primarily indicated for pain control in elderly patients with insufficiency fractures, not routinely required for all fractures 1
- Most patients can be followed clinically until pain-free, at which point controlled increase in activity is permitted 2, 1
Surgical Management (Unstable Fractures)
Surgical fixation is necessary for rotationally or vertically unstable sacral fractures, which can be identified by associated pelvic ring disruption 1, 3:
- Spinopelvic fixation allows immediate weight-bearing in vertically unstable patterns and is the treatment of choice for these injuries 1, 4
- Triangular osteosynthesis with vertical stabilization between the lumbar spine and posterior iliac crest provides the stability necessary for immediate mobilization 4
- Percutaneous posterior ring osteosynthesis to spinopelvic stabilization with or without neural decompression represents the spectrum of surgical options 3
- Neurological deficits occur in 15-64% of unstable sacral fractures depending on fracture pattern, with the highest rates in central fracture types (Denis zone III at 63.6%) and unstable pelvic ring injuries (Tile C) 5
Critical Pitfalls to Avoid
- Do not assume bracing alone is sufficient for unstable fractures that require surgical fixation, as this leads to poor outcomes 1
- Do not miss associated posterior pelvic ring injuries that would change the fracture from stable to unstable and necessitate surgical intervention 1, 5
- Do not delay diagnosis with repeat radiographs in 10-14 days when MRI is available, as this increases morbidity without benefit 1
- Do not overlook neurological complications, which are exceptional but of particular importance, especially in unstable fracture patterns 6, 5
Special Population Considerations
Elderly and Osteoporotic Patients
- Insufficiency fractures of the sacrum are frequent in postmenopausal women and predicted to triple by 2030 due to aging population 2
- Patients should be evaluated for bone mineral density and considered for osteoporosis treatment to prevent subsequent fractures 1
- Two-thirds of insufficiency fractures occur without identifiable trauma, presenting with non-specific back pain, sciatica, or pelvic pain 6
- The characteristic "Honda" or "H" sign on bone scintigraphy has a 94% positive predictive value but is only present in 63% of sacral insufficiency fractures 2
Pregnancy-Related Fractures
- Pregnancy-related sacral insufficiency fractures are rare but managed similarly to other insufficiency fractures 2
- MRI without contrast is preferred over CT to avoid fetal radiation exposure 2, 1
- Imaging findings are similar to involutional osteoporosis, except patients are women in reproductive years, typically in the last trimester 2