Sacral Insufficiency Fracture
Osteoporotic sacral fracture from normal stress on weakened bone
ICD-10: M84.38 · sacroiliac condition
A sacral insufficiency fracture occurs when normal physiological loads break weakened sacral bone — most commonly in elderly women with osteoporosis, patients who have received pelvic radiation therapy, or those on long-term corticosteroid therapy. Unlike traumatic sacral fractures, insufficiency fractures arise from routine daily activities such as walking, standing, or sitting, and the patient often cannot recall a specific injury. The classic presentation is an elderly woman (typically over 70) who develops bilateral deep sacral and buttock pain that is worse with weight-bearing and significantly impairs mobility. The pain is often attributed to lumbar disc disease, hip arthritis, or sacroiliac joint problems, and diagnosis is frequently delayed. Plain radiographs are insensitive (missed in up to 50% of cases). MRI reveals bilateral sacral alar bone marrow edema, and bone scan shows the pathognomonic "H-sign" or "Honda sign" — bilateral vertical alar uptake connected by a horizontal fracture line. Treatment traditionally consisted of bed rest, analgesics, and protected weight-bearing for 3–6 months. Sacroplasty — cement augmentation of the sacral fracture — has emerged as an effective minimally invasive option providing rapid pain relief and earlier mobilization, particularly for patients who fail or cannot tolerate conservative management.
Anatomy & Pathology
The sacrum is subject to significant compressive and shear forces during normal ambulation. In healthy bone, these forces are easily tolerated. In osteoporotic bone, the trabecular microarchitecture is disrupted, drastically reducing load-bearing capacity. Sacral insufficiency fractures most often occur in the sacral ala (the wing-like lateral portions of the sacrum adjacent to the sacroiliac joints), where stress concentration is highest. The fractures are typically vertical and bilateral, sometimes connected by a horizontal component through the sacral body — forming the H-shaped fracture pattern visible on imaging.
Symptoms
- Bilateral deep sacral, buttock, and posterior pelvic pain
- Pain significantly worsened by standing, walking, and sitting
- Severe functional limitation and inability to ambulate independently
- Insidious onset without clear traumatic event
- Point tenderness over the sacral ala bilaterally
- Absence of radicular leg pain (distinguishes from lumbar disc disease)
- History of osteoporosis, corticosteroid use, or pelvic radiation
Causes & Risk Factors
- Osteoporosis causing reduced sacral bone mineral density
- Pelvic radiation therapy inducing radiation osteonecrosis and bone fragility
- Long-term corticosteroid use accelerating bone loss
- Rheumatoid arthritis with secondary osteopenia
- Postmenopausal estrogen deficiency reducing bone density
Imaging Findings
Imaging studies are commonly used to identify findings associated with this condition. Results vary by individual; a qualified spine specialist interprets findings in the context of a full clinical evaluation.
MRI
- Imaging of choice — shows bilateral vertical marrow edema along the sacral alae
- The classic Honda sign (H-shaped edema) has an equivalent appearance on MRI
- Definitively distinguishes insufficiency fracture from infection or malignancy
CT Scan
- Useful when MRI is contraindicated; shows cortical disruption and fracture lines
- Less sensitive than MRI for early stress reactions without complete cortical breach
- Helpful for evaluating displacement and surgical planning if fixation is needed
X-Ray
- Frequently normal — sacral insufficiency fractures are easily missed on plain X-rays
- Osteopenic bone texture may be noted but is not diagnostic
- Low sensitivity makes plain films unreliable for ruling out the condition
Who Is Commonly Affected
The following patterns are commonly associated with this condition based on published population studies. Individual presentation varies; these figures are informational only.
Peak Age Range
Postmenopausal women typically older than 65 years; also occurs after pelvic radiation therapy
Gender Distribution
Strongly female predominant — approximately 80–90% of cases; related to postmenopausal bone loss and pelvic anatomy
Estimated Prevalence
Approximately 1–5% of postmenopausal women with osteoporosis; significantly underdiagnosed due to normal plain radiographs
Treatment Options
Conservative
- Protected weight-bearing with walker or bilateral crutches for 6–12 weeks
- Analgesic management: acetaminophen, NSAIDs (if not contraindicated), calcitonin nasal spray
- Osteoporosis treatment: bisphosphonates or denosumab to treat underlying fragility
Surgical
- Sacroplasty: fluoroscopy- or CT-guided PMMA cement injection into the fractured sacral ala
- Iliosacral screw fixation for bilateral fractures with significant instability
- Spinal cord stimulation for refractory neuropathic pain after fracture healing
When to see a spine specialist
An elderly patient, particularly a woman with osteoporosis, who develops bilateral deep buttock and pelvic pain without a clear injury should be evaluated for sacral insufficiency fracture. Plain X-rays are often normal; request MRI or bone scan. Early diagnosis and treatment prevent prolonged immobility, which increases fracture nonunion risk and secondary complications.
Specialists Who Treat Sacral Insufficiency Fracture
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Questions to Ask Your Doctor
Bring these questions to your next appointment about sacral insufficiency fracture.
- 1
Could my pelvic or sacral pain be a stress fracture from osteoporosis rather than a disc or arthritis problem?
- 2
What imaging is best to find a sacral insufficiency fracture — MRI, CT, or bone scan?
- 3
Do I need bed rest or surgery, and how long until I can bear weight again?
- 4
Should I start treatment for osteoporosis to prevent future insufficiency fractures?
- 5
What activities can I do during recovery, and which should I avoid?
Research Evidence
No studies reviewed yet for this condition. Check back soon — our evidence pipeline runs nightly.
Clinical Evidence
Frequently Asked Questions
What is the Honda sign on bone scan?
The Honda sign (also called the H-sign or butterfly sign) is the classic bone scan appearance of a sacral insufficiency fracture: bilateral linear uptake along the sacral ala (the vertical bars of the H) connected by a horizontal fracture line across the sacral body (the crossbar of the H), creating an H-shaped pattern. It is named for its resemblance to the Honda logo and is pathognomonic for bilateral sacral insufficiency fractures.
How quickly does sacroplasty relieve pain?
Sacroplasty typically provides immediate to next-day pain relief. Most patients report 50–80% pain reduction within 24–48 hours of the procedure, with continued improvement over 2–4 weeks. Studies show significantly better and faster pain relief compared to conservative management alone, along with earlier return to ambulatory function. The procedure takes 30–60 minutes under conscious sedation and does not require general anesthesia.
Is a sacral insufficiency fracture the same as a stress fracture of the sacrum?
These terms overlap but are not identical. An insufficiency fracture occurs when normal loads break abnormally weak bone (osteoporosis, radiation damage). A stress fracture occurs when repetitive excessive loads break normal bone (athletes). Sacral stress fractures in distance runners are rare and typically unilateral, occurring in the upper sacral ala. Insufficiency fractures are bilateral and more common in older, osteoporotic women.