Sacral fractures: issues, challenges, solutions

Key points

• Sacral fractures follow high-energy trauma in young people and minor falls in older people with osteoporosis; the incidence of non-osteoporotic fractures is about 2.1 per 100,000.
• 25 to 70% are missed or diagnosed late. Plain X-rays can miss up to 50%, so CT (68 to 88% sensitive) or MRI (98%) is needed when suspicion persists.
• Stable fractures are treated with rest, analgesia and early mobilisation; instability, displacement over 10 mm, pelvic ring injury or neurological deficit favour surgery.
• The risk of neurologic injury rises from 6% in Denis zone I to 28% in zone II and 56% in zone III.
• Healing takes 8 to 12 weeks; complications reach 40 to 50% in some fracture types, and low-energy fractures carry a 12-month mortality of about 28%.

Overview

A sacral fracture is a break in the sacrum, the bone that links the spine to the pelvic ring and provides about 60% of pelvic stability. The injury is uncommon and easy to miss, so a high index of suspicion and CT or MRI are needed. Stable fractures are treated without surgery, while unstable ones are fixed with screws or lumbopelvic fixation.

Who is affected and how fractures are classified

Fractures occur in young people after road accidents and falls from height, and in older people with osteoporosis after minor trauma. No single classification covers every case. Fractures are described by the energy of the trauma, association with pelvic ring injury (AO/OTA, Young-Burgess and, for low-energy injuries, the Fragility Fracture of the Pelvic ring classification), morphology and location. U-, H- and lambda-shaped patterns indicate spinopelvic dissociation.

Diagnosis

After high-energy trauma, look for buttock pain, bruising, perineal sensory change, sphincter dysfunction and lower-limb deficit. Low-energy fractures cause vague low back pain. If X-rays are negative and pain persists, CT is advised, and MRI is the most sensitive test, especially for insufficiency and stress fractures. Bleeding and pelvic instability need prompt treatment.

Treatment

Non-operative care means rest, analgesia and early mobilisation as tolerated. A lumbosacral injury classification score above 4 also points to surgery. The main surgical options are posterior pelvic fixation (iliosacral or transsacral screws, transiliac bridging) and lumbopelvic fixation including triangular osteosynthesis, with anterior fixation added for anterior ring injuries. Minimally invasive methods are preferred where possible.

Frequently asked questions

Why are sacral fractures often missed?

They are uncommon, present in varied ways and are often hidden on plain X-rays, which miss up to 50%. A CT or MRI should follow whenever pain persists after a negative X-ray.

When is surgery needed?

Surgery is considered for unstable or displaced fractures (over 10 mm), fractures with pelvic ring injury and fractures with neurological compromise. Stable and incomplete fractures are managed without surgery.

How long does a sacral fracture take to heal?

Healing takes 8 to 12 weeks, with fusion rates of 85 to 90%. Neurologic injuries often improve over time, but complete recovery occurs in fewer than half of patients.

Source

Santolini E, Kanakaris NK, Giannoudis PV. Sacral fractures: issues, challenges, solutions. EFORT Open Reviews 2020;5(5):299-311. DOI 10.1302/2058-5241.5.190064. Open access (CC BY-NC 4.0). This page is a summary prepared by Medpresso from the original publication. It is not a substitute for the full text or for medical advice.