What is the appropriate management of an acute sacral fracture in an adult, particularly an elderly osteoporotic patient after a low‑energy fall?

Management of Acute Sacral Fracture in Elderly Osteoporotic Patients

For an elderly osteoporotic patient with an acute sacral fracture after a low-energy fall, initiate conservative management with immediate mobilization as tolerated, multimodal analgesia avoiding opioids, and start oral bisphosphonate therapy (alendronate or risedronate) along with calcium 1000-1200mg and vitamin D 800 IU daily. 1, 2

Immediate Clinical Assessment

Determine hemodynamic stability first by checking for systolic blood pressure <90 mmHg, shock index >1, or transfusion requirements, as sacral fractures can be associated with significant pelvic bleeding requiring urgent intervention. 3 However, in elderly patients with low-energy mechanisms (simple falls), hemodynamic instability is rare and the fracture is typically an insufficiency fracture. 1, 4

Key Clinical Features to Document:

• Pain pattern: Lower back, pelvic, or sacral pain worsening with weight-bearing is classic for sacral insufficiency fractures 3
• Neurological examination: Document any bowel/bladder dysfunction, lower extremity weakness, or saddle anesthesia, though neurological deficits are uncommon in low-energy insufficiency fractures 5, 6
• Mobility status: Assess whether pain substantially limits mobilization, as this guides imaging urgency 7

Diagnostic Imaging Strategy

Obtain AP pelvis and lateral radiographs initially, but recognize that plain films have only 10.5% sensitivity for detecting sacral fractures in elderly patients due to overlying bowel gas and osteoporotic bone quality. 7

When to Proceed Immediately to CT:

• If pain substantially limits mobilization or weight-bearing, obtain CT pelvis without contrast immediately, as this indicates potential instability 7
• If radiographs are negative but clinical suspicion remains high (which it should in elderly osteoporotic patients with appropriate mechanism), proceed directly to CT 7, 3
• CT without contrast is the definitive imaging modality, with sensitivity ranging from 88-98% and superior specificity compared to other modalities 1

Role of MRI:

MRI is not necessary for diagnosis in straightforward cases but may be considered if CT is equivocal or if neurological deficits require evaluation of nerve root or spinal cord injury. 1 The characteristic "Honda sign" on bone scintigraphy has 94% positive predictive value but only 63% sensitivity, making it less useful than CT. 1

Conservative Management Protocol

Most sacral insufficiency fractures in elderly patients are managed non-operatively with excellent outcomes. 8, 4

Pain Management:

• Multimodal analgesia with acetaminophen as first-line 7
• Minimize or avoid opioids to prevent delirium in elderly patients 7
• Consider peripheral nerve blocks for severe pain 7

Mobilization Strategy:

• Allow weight-bearing as tolerated immediately - do NOT prescribe bed rest, as immobility increases mortality in elderly patients 7, 2
• Early mobilization is critical even before definitive diagnosis is confirmed 7
• Supervised physical therapy with weight-bearing exercises to improve bone mineral density and muscle strength 2

Osteoporosis Treatment (Critical for Preventing Future Fractures)

Start oral bisphosphonate therapy immediately as first-line treatment:

• Alendronate or risedronate are first-choice agents due to proven efficacy, low cost (generics available), and extensive clinical experience 1, 2
• These reduce vertebral fractures by 47-48%, non-vertebral fractures by 26-53%, and hip fractures by 51% 2

Essential Concurrent Therapy:

• Calcium 1000-1200mg daily (dietary plus supplementation if needed) 1, 2
• Vitamin D 800 IU daily - reduces non-vertebral fractures by 15-20% and falls by 20% 1, 2

Alternatives for Special Circumstances:

• Zoledronic acid (IV) or denosumab (subcutaneous) for patients with oral intolerance, dementia, malabsorption, or non-compliance 1
• Teriparatide for patients with very severe osteoporosis 1

Comprehensive Workup

Order DXA scan of lumbar spine and hip to quantify bone mineral density once patient is mobile enough to undergo testing. 2

Obtain laboratory workup to identify secondary causes of osteoporosis (CBC, BMP, calcium, phosphate, alkaline phosphatase, 25-OH vitamin D, TSH, PTH if indicated). 7, 2

Fall Prevention

Conduct multidimensional fall risk assessment and implement interventions:

• Review and optimize medications that increase fall risk 2
• Home safety evaluation 2
• Balance training exercises 1, 2
• Stop smoking and limit alcohol intake as these negatively affect bone quality 1

Surgical Indications (Rare in This Population)

Surgery is rarely indicated for sacral insufficiency fractures in elderly patients. 8 Consider surgical consultation only if:

• Neurological deficits develop or worsen (bowel/bladder dysfunction, progressive lower extremity weakness) 8, 5, 6
• Severe displacement with spinopelvic dissociation 8
• Persistent inability to mobilize despite adequate conservative management 8

Follow-Up Protocol

Follow clinically until pain-free, then gradually increase activity. 2 Typical healing time is 6-12 weeks for insufficiency fractures. 4

Red Flags Requiring Emergency Evaluation:

• New neurological deficits 2
• Severe uncontrolled pain despite appropriate analgesia 2
• Signs of infection 2
• Hemodynamic instability 2
• Evidence of new trauma with suspected acute fracture 2

Critical Pitfalls to Avoid

Do not rely solely on plain radiographs - they miss 89.5% of sacral fractures in elderly patients. 7 If clinical suspicion exists (elderly + osteoporosis + fall + sacral/buttock pain), proceed to CT even with negative X-rays. 7, 3

Do not prescribe bed rest - this is harmful in elderly patients and increases mortality. 7 Weight-bearing as tolerated should begin immediately. 7, 2

Do not dismiss vague pelvic or lower back pain as "arthritis" without imaging in elderly patients with appropriate mechanism. 3 The presentation is often insidious. 3, 4

Do not delay osteoporosis treatment - the fracture itself is the indication to start therapy, and waiting for DXA results is unnecessary, particularly in patients with hip or pelvic insufficiency fractures who may not respond to outpatient follow-up invitations. 1

Orthogeriatric Comanagement

Activate interdisciplinary orthogeriatric consultation for frail elderly patients with multiple comorbidities and polypharmacy to optimize medical management and reduce complications. 1, 7 This structured collaboration between specialties improves outcomes. 1