Assess stability and neurology with TLICS; Load Sharing Classification (McCormack) predicts need for anterior support. High load‑sharing score (≥7) → consider anterior column reconstruction with corpectomy/cage in addition to posterior fixation. Posterior pedicle screw constructs (short vs long segment) are standard; add intermediate screws at the fractured level to improve stability. Canal compromise alone is not an absolute indication for laminectomy—retropulsed fragments resorb over time if PLC intact and no neuro deficit. Monitor for kyphosis progression and failure of short constructs in highly comminuted fractures.
10 AI-generated high-yield questions by our AI engine
Overview & Mechanism
Thoracolumbar burst fractures are high-energy injuries resulting from axial compression of the spine, typically at the thoracolumbar junction (T11–L2) — the most biomechanically vulnerable region of the spine due to the transition from the rigid thoracic spine (stabilised by the rib cage) to the more mobile lumbar spine. In a burst fracture, axial load causes the vertebral body to fail in all planes — the anterior and middle columns are disrupted, bone fragments and disc material are retropulsed into the spinal canal, and the posterior elements may also be disrupted. The Load Sharing Classification (LSC) is the principal tool for guiding surgical decision-making in these fractures.
Mechanism: axial compression ± flexion; high-energy trauma (road traffic accidents, falls from height, diving injuries); the thoracolumbar junction T11–L2 accounts for approximately 50–60% of all thoracic and lumbar spine fractures; the nucleus pulposus of the disc is driven explosively into the vertebral endplate, fracturing it centrifugally; bone fragments are retropulsed into the spinal canal — the middle column (posterior vertebral body wall) is characteristically disrupted
Denis three-column concept (1983): the three-column model is the foundation of thoracolumbar fracture classification; the anterior column = anterior longitudinal ligament (ALL) + anterior half of the vertebral body and disc; the middle column = posterior longitudinal ligament (PLL) + posterior half of the vertebral body and disc; the posterior column = posterior elements (pedicles, facets, lamina, posterior ligamentous complex — PLC: supraspinous ligament, interspinous ligament, facet capsules, ligamentum flavum); burst fractures disrupt the anterior AND middle columns; if the posterior column is also disrupted, the fracture is highly unstable; the integrity of the PLC is the single most important factor in surgical decision-making
Thoracolumbar Injury Classification and Severity (TLICS) score: the modern classification system; assesses three parameters: (1) morphology (compression = 1; burst = 2; translational/rotation = 3; distraction = 4); (2) neurological status (intact = 0; nerve root injury = 2; complete cord/conus/cauda equina injury = 2; incomplete cord/conus = 3); (3) posterior ligamentous complex (intact = 0; suspected/indeterminate = 2; disrupted = 3); total TLICS score 0–10; score ≤3 = non-operative; score 4 = either; score ≥5 = surgical; the TLICS is now preferred over the Denis system and LSC for overall management decisions
Load Sharing Classification (McCormack 1994)
The Load Sharing Classification (LSC), developed by McCormack, Karaikovic, and Gaines, was specifically designed to determine whether short-segment posterior fixation alone (typically 2 levels above and 2 levels below the fracture) will be sufficient to maintain stability, or whether the anterior column needs to be reconstructed to share the load and prevent hardware failure. It assesses three parameters on CT scan, each scored 1–3.
Parameter
Score 1
Score 2
Score 3
Comminution of the vertebral body
Minimal comminution — <30% of the vertebral body is involved; one large fragment
Moderate — 30–60% involvement; multiple fragments
Severe — >60% of the body is comminuted; extensive fragmentation
Apposition of fracture fragments
Minimal loss of apposition — <1 mm separation between fragments; fragments in close contact (high potential for load sharing across the fracture)
1–2 mm separation — moderate gap; some load transfer possible
>10° correction needed — significant kyphosis requiring correction; the more correction required, the greater the bending moment placed on posterior instrumentation
Total LSC Score
Interpretation
Surgical Implication
3–6
Low load-sharing demand — the anterior column retains sufficient integrity to share the compressive load after posterior fixation
Short-segment posterior fixation (2 above + 2 below) alone is likely sufficient; anterior column reconstruction NOT required; hardware failure risk is low
>6 (7–9)
High load-sharing demand — the anterior column is so comminuted and fragmented that it cannot share load; all compressive forces will be borne by posterior instrumentation alone
Short-segment posterior fixation ALONE will fail (high risk of rod breakage, screw pullout); anterior column reconstruction required — either anterior approach with vertebral body replacement (VBR, titanium mesh cage or PEEK cage) + anterior instrumentation, OR posterior approach with additional intermediate screw at the fracture level (`fracture pedicle screw` technique to reduce cantilever forces); alternatively, long-segment posterior fixation (3 above + 3 below) distributes loads over more levels
Rationale for the Load Sharing Classification: after posterior pedicle screw fixation of a burst fracture, the rods are subjected to cyclic bending loads (cantilever bending) because the body is supported from behind; if the anterior column cannot resist axial compression (high comminution, wide fragment separation), the posterior rods bear ALL of the compressive load over the fracture site — they will fatigue and break (rod fracture) before the fracture heals; the LSC predicts which fractures need anterior column support to share this load; for LSC >6, anterior reconstruction (creating a structural column anteriorly) or long-segment posterior fixation dramatically reduces the cantilever bending forces on the rods
Non-operative — thoracolumbar orthosis (TLSO) for 3 months; early mobilisation; repeat standing radiographs at 6 weeks and 3 months to assess kyphosis progression; physiotherapy; activity modification; most neurologically intact burst fractures can be managed non-operatively — the TLICS and LSC are used to identify which ones
Neurologically intact, PLC intact, high comminution
≥5 (burst morphology 2 + intact PLC 0 + neural intact 0 — may be borderline depending on other factors)
>6
Surgical — posterior pedicle screw fixation ± anterior column reconstruction; even in the absence of neurological deficit, if the fracture has high LSC score, surgery prevents progressive kyphosis and hardware failure; TLICS may be borderline (4) — individual decision
Neurological deficit (incomplete cord or cauda equina), PLC disrupted
≥5–8
Any
Urgent surgical decompression and stabilisation; posterior decompression (laminectomy/corpectomy) + pedicle screw fixation; if LSC >6 → anterior column reconstruction or long-segment fixation; timing: within 24 hours for incomplete neurological deficits (time-critical neurological recovery); within 72 hours for complete cord injuries (stabilisation); earlier surgery associated with improved neurological outcomes for incomplete injuries
Complete cord injury (ASIA A)
High TLICS but prognosis for neurological recovery is poor
Any
Surgery primarily for stabilisation and early mobilisation (nursing, rehabilitation, pain control) rather than neurological recovery; early surgery reduces complications (PE, pneumonia, pressure sores) through early mobilisation; reconstruction based on LSC as above
Surgical Approaches
Posterior approach (pedicle screw fixation): the workhorse surgical approach; bilateral pedicle screws placed 2 levels above and 2 levels below the fracture (short-segment) or 3 above and 3 below (long-segment); connected by rods; provides indirect decompression (ligamentotaxis — distraction across the fractured level restores vertebral height and partially reduces retropulsed fragments by stretching the PLL); pedicle screws at the fracture level (intermediate screws) significantly reduce the cantilever bending forces on the construct and may allow short-segment fixation even for LSC >6; intraoperative CT or fluoroscopy confirms screw placement and fragment reduction; direct posterior decompression (laminectomy, transpedicular) can address retropulsed fragments not reduced by ligamentotaxis
Anterior approach (anterior column reconstruction): thoracotomy or retroperitoneal approach; corpectomy (removal of the fractured vertebral body); anterior column reconstruction with expandable titanium cage or PEEK cage packed with bone graft; anterior instrumentation (plate or rod); restores anterior column integrity and directly decompresses the spinal canal; anterior approach provides the most reliable canal decompression but is associated with greater surgical morbidity (approach-related: diaphragm mobilisation, vascular injury, retrograde ejaculation from superior hypogastric plexus injury, pulmonary complications); combined anterior-posterior approach for the most complex unstable fractures
Percutaneous minimally invasive pedicle screw fixation: increasingly used for neurologically intact burst fractures requiring stabilisation; pedicle screws inserted percutaneously (through 2 cm skin incisions) under fluoroscopic guidance; dramatically reduces muscle trauma, blood loss, and hospital stay; preserves the posterior tension band; avoids the extensive posterior muscle stripping of open surgery; particularly suitable for young patients with isolated burst fractures (no posterior ligamentous complex disruption) who need early mobilisation; fracture reduction can be achieved using postural reduction tables before/during screw insertion; can be combined with kyphoplasty (balloon vertebroplasty at the fracture level) to restore vertebral height
Exam Pearls
Thoracolumbar junction (T11–L2): 50–60% of all thoracolumbar fractures; transition from rigid (rib-stabilised thoracic) to mobile lumbar; burst fracture = anterior + middle column failure ± posterior
LSC >6 rationale: anterior column cannot resist axial compression → posterior rods bear ALL load → cantilever bending fatigue → rod fracture/screw pullout; anterior reconstruction or long-segment fixation shares the load
Ligamentotaxis: distraction via posterior pedicle screws stretches the PLL and partially reduces retropulsed fragments; most effective within 72 hours (before callus formation); posterior indirect decompression
Posterior intermediate screws (fracture pedicle screws): placed at the fracture level in addition to standard 2-above-2-below construct; dramatically reduces cantilever bending forces; may allow short-segment fixation for some LSC >6 cases without anterior reconstruction
Neurological timing: incomplete cord/conus/cauda equina = urgent decompression within 24 hours (time-critical neurological recovery); complete cord injury = stabilisation within 72 hours for early mobilisation and complications prevention
Percutaneous MIS fixation: neurologically intact, LSC ≤6 fractures; minimal muscle trauma; lower blood loss; early mobilisation; combined with kyphoplasty for height restoration; fluoroscopic guidance
PLC assessment: MRI best identifies PLC disruption (ligamentum flavum, interspinous, supraspinous ligament signal abnormality); clinical examination — tenderness at spinous processes; widening of interspinous gap; facet subluxation/dislocation on CT
10 AI-generated high-yield questions by our AI engine
References
McCormack T, Karaikovic E, Gaines RW. The load sharing classification of spine fractures. Spine. 1994;19(15):1741–1744.
Denis F. The three column spine and its significance in the classification of acute thoracolumbar spinal injuries. Spine. 1983;8(8):817–831.
Vaccaro AR et al. A new classification of thoracolumbar injuries: the importance of injury morphology, the integrity of the posterior ligamentous complex, and neurologic status. Spine. 2005.
Wood K et al. Operative vs nonoperative treatment of thoracolumbar burst fractures without neurological deficit. J Bone Joint Surg Am. 2003.
McLain RF et al. Functional outcomes after surgery for spinal fractures. Spine J. 2009.
Verlaan JJ et al. Surgical treatment of traumatic fractures of the thoracic and lumbar spine. Spine. 2004.
Kingwell SP et al. Fractures of the thoracolumbar spine. J Bone Joint Surg Am. 2010.
Campbells Operative Orthopaedics. 14th Edition. Elsevier.
Orthobullets — Thoracolumbar Burst Fractures; TLICS; Load Sharing Classification; Denis Three-Column.
Wang H et al. Percutaneous pedicle screw fixation for thoracolumbar burst fractures. Spine. 2015.
