La enfermedad del segmento adyacente se refiere al fenómeno de hipermovilidad inmediatamente después a un segmento rígido, el cual condiciona a radiculopatía o mielopatía. Los factores que propician la aparición de este fenómeno son múltiples, los más estudiados son la pérdida de movilidad segmentaria, alteración de la alineación sagital y cirugía multinivel. Existe evidencia que posterior a un procedimiento cervical es más importante la alineación segmental y no la global, lo cual afecta el resultado. En este caso se analiza la realización de una fusión anterior y su afección en la dinámica nativa por el cambio del balance sagital de 68 mm, que sobrecarga la columna anterior y segmentos adyacentes, lo que remarca la correlación en la literatura de una evolución tórpida posterior a los 40 mm del eje sagital vertical. Dentro de la literatura hay pocos estudios que correlacionen la enfermedad del segmento adyacente y el balance sagital, en los cuales la correlación se establece de manera radiológica y no clínicamente, por lo cual se decide publicar este caso y agregar evidencia a esta correlación dando importancia a la planeación prequirúrgica para mantener y/o corregir el balance sagital cervical al realizar cirugía descompresiva y fusión para mielopatía cervical.

In fracture dislocations of the lumbar region, two anatomical facts can help preserve neurological damage in patients, when compared with trauma in the cervical or thoracic region. Firstly, the spinal cord in adults extends only to the lower edge of the first lumbar vertebra, and secondly, the large vertebral space in this region gives ample space for the roots of the cauda equine. As a result, the nerve injury may be minimal, because the nerve roots in this region are accommodated in a larger area, with less content and space. This study presents the case of a 48 year-old male, a construction worker, who suffered a fall from a height of approximately 15 meters, directly hitting the lumbar region against a beam, and presenting pain and inability to move the legs. The patient was brought to the emergency room one hour after the accident, clinically assessed, submitted to x-rays and a CT scan, and diagnosed as having an ASIA B L3-L4 fracture dislocation. Three hours after the accident, reduction was performed via posterior transpedicular fixation. One week later, an anterior approach was performed. The patient progressed to ASIA C 24 hours after the first surgery. Three months later, the patient was functional with ASIA D and good sphincter control. The author's purpose is to show the results obtained by an intervention in the initial hours of the trauma, which helped promote the evolution from a nonfunctional injury to a functional one, with near-total recovery.Keywords: Dislocations/surgery; Lumbar vertebrae/injuries; Spinal fractures/surgery; Thoracic vertebrae/injuries; Accidental. RESUMO Nas fraturas-luxações da região lombar dois fatos anatômicos podem contribuir para o paciente apresentar menos danos neurológicos em comparação aos traumatismos na cervical ou torácica. Em primeiro lugar, a medula espinhal no adulto se estende apenas até o nível da

Objective: In traumatic injuries of the thoracic spine, three variables are analyzed to make decisions: morphology of the injury, posterior ligamentous complex and neurological status; currently the fourth column is not evaluated; our objective was to determine the biomechanical behavior of the spine with a fracture of the fifth thoracic vertebral body when accompanied by a short oblique fracture of the sternum. Methods: An anonymous model of a healthy 25-year-old male was used, from which the thoracic spine and rib cage were obtained; in addition to the ligaments of the posterior complex and the intervertebral discs, four models were simulated. An axial section was made, a load of 400 N was applied, and the biomechanical behavior of each model was determined. Results: The area that suffered the most stress at the vertebral level was the posterior column of T4-T5 (tensile strength of 747 MPa), which exceeded the plastic limit, the load through the ribs was distributed from the first to the sixth (100 MPa), in the sternum the stress increased (200 MPa), the deformity increased to 45 mm. Conclusions: The sternum was a fundamental part of the spine’s stability; the combined injury severely increased the stress (8 MPa to 747 MPa) in the spine and exceeded the plastic limit, which generated an instability that is represented by the global deformity acquired (1 mm to 45 mm). Level of evidence II; Prospective comparative study.