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Chapter Summary
• Context: Post-traumatic spinal deformities represent a complex late sequela of spinal injuries characterized by progressive structural malalignment, most frequently developing as fixed focal, regional, or global post-traumatic kyphosis (PTK). Deformities develop following either failed non-operative management (unrecognized posterior tension band rupture, severe initial vertebral comminution, early brace discontinuation) or surgical failure (inadequate initial reduction, insufficient anterior column support leading to hardware fatigue, screw loosening, nonunion/pseudarthrosis, or wrong-level instrumentation). Biomechanically, focal kyphotic collapse shifts the trunk center of mass anteriorly, substantially lengthening the gravitational lever arm and subjecting anterior vertebral bodies to progressive compressive overload while placing posterior musculature in chronic, exhausting fatigue. Patients present with chronic intractable mechanical back pain, accelerating adjacent segment degeneration, sagittal imbalance (positive SVA), compensatory pelvic retroversion and knee flexion, and late neurological deterioration (delayed myelopathy or radiculopathy caused by tethering and draping of the spinal cord over the anterior bony kyphotic ridge). Evaluation requires standing whole-spine full-length radiographs (spinopelvic parameters), multiplanar CT (assessing osseous bridging and pseudarthrosis), and MRI (evaluating neural compression). Reconstructive surgery demands advanced spinal osteotomies (Posterior Column Osteotomies [PCO / Smith-Petersen], Pedicle Subtraction Osteotomy [PSO], or Vertebral Column Resection [VCR]) combined with anterior column reconstruction and robust multi-rod instrumentation to restore sagittal balance and decompress neural elements.
• Chapter Objective: To present the etiology, biomechanical cascade, clinical evaluation, and surgical correction principles of post-traumatic spinal deformities. The reader should be able to identify primary causes of post-traumatic kyphosis; evaluate global spinopelvic sagittal alignment; recognize delayed post-traumatic myelopathy; select appropriate osteotomy techniques (PCO, PSO, VCR) based on curve flexibility and focal angular severity; and execute reconstruction while minimizing complications such as neurovascular injury and junctional failure.
• Pathogenesis and Biomechanical Failure CascadePost-traumatic kyphosis results from progressive anterior column height loss, disc degeneration, and failure of the posterior tension band. Once focal kyphosis exceeds 20°–30°, the gravity line shifts anterior to the instantaneous axis of rotation, generating an escalating flexion bending moment. This mechanical stress causes chronic muscle strain, disc degeneration at adjacent levels, and anterior vertebral remodeling. In severe cases, the spinal cord and conus medullaris are draped tightly over the sharp posterior-superior margin of the retropulsed vertebral body, causing chronic microvascular ischemia, cord flattening, and progressive myelopathy.
• Clinical Presentation: Pain, Sagittal Imbalance, and MyelopathyClinical manifestations comprise: 1) Severe chronic mechanical back pain localized to the deformity apex and compensatory hyperlordotic segments; 2) Postural fatigue and sagittal imbalance (stooped forward posture, inability to stand upright without knee flexion); 3) Neurological deficits (delayed post-traumatic myelopathy or radiculopathy appearing months to years after trauma); 4) Functional limitations in walking distance, social interaction, and activities of daily living.
• Radiological Evaluation and Spinopelvic MappingDiagnostic workup requires: 1) 36-inch standing whole-spine radiographs: measuring local kyphosis angle (Cobb method), regional lumbar lordosis, Sagittal Vertical Axis (SVA), Pelvic Incidence (PI), Pelvic Tilt (PT), and T1 Pelvic Angle (TPA); 2) Supine hyperextension bolster radiographs: testing curve flexibility (differentiating mobile flexible kyphosis from rigid ankylosed deformity); 3) Multi-detector CT: identifying pseudarthrosis, implant breakage, anterior bone bridging, and canal stenosis; 4) MRI: assessing spinal cord draping, syringomyelia, and disc degeneration at adjacent levels.
• Surgical Decision-Making and Osteotomy SelectionSurgical correction is indicated for severe unremitting pain, progressive deformity (>20°–30° focal kyphosis with global sagittal malalignment), and progressive neurological deficit. The choice of osteotomy is tailored to curve flexibility and magnitude: 1) Posterior Column Osteotomies (PCO / Ponte / Smith-Petersen): indicated for mobile, flexible deformities with intact anterior disc spaces, achieving 5°–10° lordosis per level; 2) Pedicle Subtraction Osteotomy (PSO): a 3-column closing wedge osteotomy through the fractured vertebral body, ideal for rigid, sharp angular kyphosis, yielding 30°–40° focal correction; 3) Vertebral Column Resection (VCR): complete removal of the diseased vertebral body and adjacent discs, reserved for severe, rigid, fixed multiplanar deformities and sharp bony ridges causing cord compression.
• Instrumentation Strategies and Complication PreventionRigid multi-rod constructs (3-rod or 4-rod configurations with accessory/satellite rods) are essential across PSO and VCR sites to prevent rod fatigue breakage. Anterior column support with structural cages restores load sharing. Continuous intraoperative neuromonitoring (TcMEP, SSEP, and D-wave) is mandatory during osteotomy closure and spinal cord decompression. Prevent proximal junctional kyphosis (PJK) by avoiding rigid overcorrection, terminating constructs on stable neutral vertebrae, and applying ligamentous augmentation at the upper instrumented vertebra (UIV).
• Clinical Application: In clinical practice, evaluating a patient with post-traumatic kyphosis begins with full-length 36-inch standing radiographs to calculate global alignment (SVA, PT, PI–LL). If a 45-year-old patient with an untreated L1 fracture presents with 35° focal kyphosis, positive SVA (+9 cm), exhausting back pain, and progressive lower extremity spasticity, obtain CT and MRI. CT demonstrates a healed, rigid, wedged L1 vertebral body; MRI reveals the conus medullaris compressed and stretched over the retropulsed bone ridge. A single-stage posterior L1 Pedicle Subtraction Osteotomy (PSO) or Vertebral Column Resection (VCR) with intraoperative TcMEP/SSEP monitoring allows direct anterior cord decompression, closes the wedge to achieve 35° of lordotic correction, and restores sagittal balance. Secure the construct with a 4-rod configuration and extend instrumentation from T10 to L4 to prevent mechanical failure.
