Thoracolumbar Burst Fracture

A thoracolumbar burst fracture is a compression failure of the vertebral body in which the middle column (the posterior wall of the vertebral body) fractures. Fragments may be retropulsed into the spinal canal, with comminution of the body and widening of the interpedicular distance. It follows axial loading with variable flexion, and affects the thoracolumbar junction (T11 to L2) most often.

Burst fractures account for about 10 to 20% of all thoracolumbar fractures. They occur in young adults after road traffic collisions and falls from height (peak 20 to 40 years, men more than women) and in older adults with osteoporosis after low energy falls.

Associated injuries are frequent: other spinal fractures in 20 to 40% (non-contiguous), calcaneal and lower limb fractures in falls, and chest and abdominal injuries.

A neurological deficit is present in 20 to 40%, and is more likely with canal compromise over 50% and burst fractures at L1.

Complications are cord or cauda equina injury, progressive kyphosis, chronic back pain, instability, implant failure, wound infection and venous thromboembolism.

The decision between bracing and surgery is based on neurological state, mechanical stability and the integrity of the posterior ligamentous complex.

Pathophysiology.

Axial compression drives the nucleus pulposus into the endplate, which causes a burst of the vertebral body with retropulsion of the posterior cortex. The transition from the rigid thoracic spine to the mobile lumbar spine concentrates load at T12 to L1.

Stability depends on the posterior ligamentous complex (supraspinous, interspinous ligaments, ligamentum flavum and facet capsules) and on the degree of vertebral height loss and kyphosis. Fragments in the canal may undergo remodelling over months in non-operative treatment.

Severe back pain at the level of injury, worse with movement and eased by lying; spinal tenderness or a palpable gap between spinous processes; and abnormal sensation or weakness. A neurological deficit can range from isolated root symptoms to incomplete or complete conus or cauda equina syndrome (sphincter dysfunction, saddle anaesthesia). Look for associated injuries, abdominal pain, haematuria and heel pain.

Examine under spinal precautions with log rolling: full neurological examination including perianal sensation, anal tone and bulbocavernosus reflex; grade the injury and record it before and after interventions; skin, abdomen, pelvis, and lower limbs.

• CT of the thoracolumbar spine with sagittal and coronal reformats (the key test): vertebral body comminution, retropulsion, canal compromise (percentage of canal narrowed), kyphosis angle, interpedicular distance, posterior element fractures (laminar fracture with dural entrapment in neurological deficit).
• MRI: spinal cord, conus or cauda equina injury, epidural haematoma, disc disruption and integrity of the posterior ligamentous complex (high STIR signal).
• Whole spine CT to exclude non-contiguous injuries; CT of the chest, abdomen and pelvis depending on the mechanism.
• Classification: AO Spine type A3 (incomplete burst, one endplate) and A4 (complete burst, both endplates).
• The thoracolumbar injury classification and severity score:
  • morphology (compression 1, burst 2, translation or rotation 3, distraction 4)
  • integrity of the posterior ligamentous complex (intact 0, suspected 2, injured 3)
  • neurological state (intact 0, nerve root 2, complete cord 2, incomplete cord or cauda equina 3)
• A total of 3 or less suggests non-operative care, 4 is borderline, and 5 or more suggests surgery.

Differential diagnosis.

• Compression (wedge) fracture and flexion distraction (Chance) fracture.
• Fracture dislocation.
• Pathological fracture from metastasis, myeloma or osteoporosis.
• Infection and tumour with vertebral collapse.

The aims are to protect and decompress neural tissue, restore alignment and stability, allow early mobilisation, and prevent complications.

Non-operative care (neurologically intact, stable fractures: kyphosis under 25 to 30 degrees, canal compromise under 50%, vertebral height loss under 50%, intact posterior ligamentous complex, thoracolumbar injury classification score 3 or less).

• Early mobilisation with analgesia, with or without a thoracolumbosacral orthosis for 8 to 12 weeks (outcomes with early functional treatment without brace match those with bracing and cast in many studies, with fewer skin and respiratory complications).
• Radiographs standing at 1 to 2 weeks, 6 weeks and 12 weeks to monitor kyphosis.
• Physiotherapy for core strength; return to work at 3 to 6 months.

Surgery (neurological deficit with canal compromise, unstable pattern, posterior ligamentous complex injury, kyphosis over 25 to 30 degrees or progressive, vertebral height loss over 50%, polytrauma, or thoracolumbar injury classification score 5 or more).

• Posterior short segment pedicle screw fixation (one level proximal and one distal), or long segment fixation (two levels proximal and two distal) in osteoporotic bone or for severe kyphosis, with or without posterolateral fusion.
• Indirect reduction by ligamentotaxis; laminectomy and direct decompression for neurological deficit with retropulsion.
• Anterior or lateral corpectomy with cage reconstruction (and plate) for severe comminution, canal compromise with deficit, or failed posterior surgery; combined approaches for very unstable injuries.
• Minimally invasive percutaneous fixation for fractures without need for direct decompression.
• Time of surgery: within 24 hours for incomplete neurological deficit or progressive deterioration; early stabilisation (within 72 hours) in polytrauma.
• Complications: infection 1 to 5%, dural tear, implant failure or kyphosis, adjacent segment disease, chronic back pain (up to 30 to 50%), screw malposition.

Spinal cord injury care (when a deficit exists).

• Maintain mean arterial pressure at 85 to 90 mm Hg for 5 to 7 days (noradrenaline 0.05 to 0.5 micrograms/kg/minute intravenously, titrated).
• Methylprednisolone is not used routinely.
• Bladder catheterisation then intermittent catheterisation; bowel programme; pressure care.
• Omeprazole 40 mg orally or intravenously once daily.

Operative antibiotic prophylaxis.

• Cefazolin 2 g intravenously (3 g when weight is 120 kg or over) within 60 minutes before incision, repeated after 4 hours or blood loss over 1500 mL.
• With severe penicillin allergy, vancomycin 15 mg/kg intravenously starting 90 to 120 minutes before incision as a single dose, with levels and creatinine checked in prolonged cases.
• Intrawound vancomycin powder 1 g is used in some centres.

Tranexamic acid. Tranexamic acid 15 mg/kg (maximum 1 g) intravenously over 10 minutes before incision, repeated once after 3 hours if bleeding continues (maximum 2 g).

Avoid with a history of thromboembolism, active intravascular clotting, seizures, or recent coronary stent. Reduce the dose at creatinine clearance under 50 mL/min.

Thromboprophylaxis.

• Mechanical prophylaxis from admission.
• Enoxaparin 40 mg subcutaneously once daily started 24 to 72 hours after injury or surgery once haemostasis is secure (20 mg at creatinine clearance under 30 mL/min; check the platelet count on days 5 to 14).
• Continue for 4 to 6 weeks, and for 8 to 12 weeks in complete cord injury.

Analgesia.

• Paracetamol 1 g orally every 6 hours (maximum 4 g daily; 3 g daily when weight is under 50 kg, with chronic alcohol use or hepatic impairment).
• Oral morphine 5 to 10 mg every 4 hours as needed for severe pain for up to 3 to 5 days (start 2.5 to 5 mg with age over 75 or eGFR under 30 mL/min/1.73 m2); monitor sedation and respiration; laxative.
• Neuropathic pain: gabapentin 300 mg orally at night, increased to 300 to 600 mg three times daily (maximum 3600 mg daily; reduce at creatinine clearance under 60 mL/min).
• Or pregabalin 75 mg orally twice daily, increased to 150 mg twice daily (maximum 300 mg twice daily).
• Avoid NSAIDs for the first weeks when fusion is planned, and in renal or gastrointestinal risk.

Osteoporotic burst fractures. Treat osteoporosis (calcium 1000 to 1200 mg daily in total, vitamin D 800 to 2000 units daily, alendronate 70 mg orally once weekly or zoledronic acid 5 mg intravenously once yearly after correcting vitamin D deficiency); consider cement augmented fixation.

Monitoring.

• Neurological examination every 1 to 4 hours in the first 24 to 48 hours.
• Wound review at 2 weeks.
• Radiographs at 2 weeks, 6 weeks, 3 months, 6 months and 12 months for alignment and implant position.
• CT for fusion at 12 months if pain persists.
• Bladder, bowel and pressure injury checks; bone health.

Referral and escalation. Every suspected burst fracture needs spinal precautions and a spinal surgical opinion the same day. Emergency referral for any neurological deficit, progressive weakness, bladder or bowel dysfunction, or fracture dislocation.

Special groups.

• Polytrauma: early stabilisation facilitates nursing and respiratory care.
• Older adults and osteoporosis: long segment fixation with cement augmentation; bone protective therapy.
• Children: more stable patterns; bracing preferred with remodelling potential.
• Pregnancy: avoid radiation where possible; MRI without gadolinium; coordinate with obstetrics.