Chance fracture is an unstable thoracolumbar spine injury characterized by horizontal disruption/fracture through all three columns via flexion-distraction mechanism. First described in 1948 by G.Q. Chance. Seatbelt mechanism (motor vehicle collision — MVC) is the most common cause: the upper body is thrown forward while the pelvis is restrained by the seatbelt, exposing the spine at pelvic level to flexion + distraction forces. Posterior elements (spinous process, lamina, pedicle) and middle column undergo distraction, anterior column shows compression or distraction. Sagittal CT reformation is pathognomonic: horizontal fracture line traverses the entire vertebra from posterior to anterior. PLC (posterior ligamentous complex) injury appears STIR hyperintense on MRI — confirming instability. Thoracolumbar junction (T12-L2) is the most commonly affected region. Abdominal organ injury (spleen, bowel, mesentery, kidney) accompanies in 50% of patients — abdominal CT screening is mandatory.
Age Range
15-60
Peak Age
35
Gender
Equal
Prevalence
Uncommon
The biomechanics of Chance fracture are based on the Denis three-column concept. During MVC, the three-point seatbelt fixes the pelvis and lower abdomen — at impact, the torso is thrown forward by inertia, creating a pivot point at seatbelt level. Flexion + distraction forces develop around this pivot: posterior structures (spinous process, supraspinous ligament, interspinous ligament, ligamentum flavum, facet joint capsule) are stretched and torn — this is PLC (posterior ligamentous complex) rupture. Middle column (posterior vertebral body, posterior longitudinal ligament, posterior disc annulus) disrupts horizontally. Anterior column shows compression or distraction — in pure distraction variant, ALL is also torn. Bony and/or ligamentous structures rupture in the horizontal plane: 'osseous Chance' (fracture through bone), 'ligamentous Chance' (disruption through ligament), or 'osseo-ligamentous' (mixed). Thoracolumbar junction (T12-L2) is the most vulnerable region because the relatively rigid thoracic kyphosis meets the mobile lumbar lordosis here — mechanical stress concentrates. STIR hyperintensity on MRI shows PLC edema: ligament fibers develop micro- and macro-tears from mechanical failure, fluid leaks from surrounding tissue and extracellular water accumulates. Horizontal fracture line on CT demonstrates cortical bone discontinuity — X-rays make this visible by detecting the density difference between soft tissue/air in the fracture gap and bone.
Single horizontal fracture line extending from spinous process to vertebral body on sagittal CT reformation. Traverses posterior, middle, and anterior columns. No or minimal retropulsion. Pathognomonic finding of flexion-distraction mechanism.
Horizontal fracture line traverses all three columns on sagittal CT reformation: starting posteriorly (spinous process), progressing through lamina and pedicle, ending in the anterior vertebral body. Fracture line may be straight or slightly curved. In osseous variant, clear cortical discontinuity through bone is seen. Axial sections show bilateral pedicle fracture and lamina separation.
Report Sentence
Horizontal fracture line traversing all three columns at [vertebra] level, consistent with flexion-distraction (Chance) injury.
Hyperintense signal in the posterior ligamentous complex region (supraspinous ligament, interspinous ligament, ligamentum flavum) on STIR — indicating edema and ligament rupture. Intact ligaments show low signal on STIR while damaged ligaments show high signal. This finding scores 3 points in the TLICS system and strengthens surgical indication.
Report Sentence
STIR hyperintense signal in the posterior ligamentous complex at [vertebra] level suggesting PLC rupture and supporting instability.
Distraction of posterior elements is seen on sagittal and axial CT: facet joint surface separation (diastasis), spinous process tips separating (increased interspinous distance), lamina fracture and separation. Pedicle fracture is detected bilaterally. Normal facet joint gap is <2 mm; marked widening is seen in Chance fracture.
Report Sentence
Bilateral facet joint diastasis, lamina and pedicle fractures at [vertebra] level with posterior element distraction consistent with Chance fracture.
MRI evaluates spinal cord injury: cord edema (T2 hyperintense), cord contusion, cord transection, or cord compression. Retropulsion is generally not prominent in Chance fracture — neurological injury is less common than in burst fracture. However, disc herniation in ligamentous variant may cause cord compression.
Report Sentence
Spinal cord signal characteristics at fracture level are normal / cord edema is present / cord compression is noted — neurological correlation required.
Abdominal organ injury accompanies 50% of Chance fracture patients — seatbelt compression also damages abdominal organs. Most common: bowel perforation/contusion, mesenteric tear, splenic laceration, renal injury, pancreatic trauma. Free fluid, active bleeding, bowel wall thickening, and mesenteric fluid should be investigated.
Report Sentence
Free abdominal fluid / solid organ injury / bowel wall pathology is/is not present accompanying Chance fracture — clinical correlation required.
Criteria
Fracture line runs through bone. Clear cortical discontinuity on CT.
Distinct Features
Conservative treatment with brace may be considered. Bone healing potential exists. Better prognosis.
Criteria
Disruption through ligaments and disc. PLC + disc + ALL rupture on MRI.
Distinct Features
Surgical stabilization mandatory (ligament does not heal spontaneously). Disc herniation may accompany.
Criteria
Both bone and ligament components. Posterior bone + anterior disc/ligament.
Distinct Features
Most common variant. Surgery usually required. CT + MRI should be evaluated together.
Distinguishing Feature
Burst fracture results from axial loading mechanism — vertebral body shows centrifugal fragmentation with posterior cortex fragment retropulsing into spinal canal. Chance mechanism is flexion-distraction with no retropulsion and horizontal fracture line through three columns. Burst shows posterior element compression/fragmentation; Chance shows posterior element distraction.
Distinguishing Feature
Compression fracture affects only the anterior column — anterior vertebral height decreased, posterior vertebral height preserved. In Chance, all three columns are horizontally disrupted. Compression fracture is stable; Chance is unstable. Posterior elements normal in compression; damaged in Chance.
Distinguishing Feature
Traumatic disc herniation may accompany the ligamentous component of Chance injury but isolated disc herniation does not show bone fracture and PLC injury. Horizontal bone fracture on CT and/or PLC rupture on MRI is mandatory in Chance. Vertebral body is intact in isolated disc herniation.
Urgency
emergentManagement
surgicalBiopsy
Not NeededFollow-up
specialist-referralChance fracture is an unstable thoracolumbar injury requiring emergent evaluation. TLICS score is generally ≥5 (posterior ligament injury 3 points + distraction mechanism 3 points), strongly indicating surgery. Conservative treatment (extension brace, 8-12 weeks) may be considered in osseous variant, but surgical stabilization (posterior instrumentation and fusion) is required in ligamentous/mixed variants. Abdominal organ screening is mandatory — 50% of patients have accompanying bowel, mesenteric, splenic, or renal injury. Neurological examination and spinal cord MRI assessment should be performed. Emergency physicians should actively search for Chance fracture in the presence of seatbelt sign.
Chance fracture is an unstable injury — posterior ligamentous complex is disrupted. Surgical stabilization (posterior fusion) is usually required. Screening for abdominal organ injury is mandatory (50% association). Neurological examination and spinal cord assessment (MRI) should be performed. Chance fracture should be actively sought in the presence of seatbelt sign.