Tornillos Pediculares Lumbares.

Question 1

Lumbar Pedicle Screw Placement
- Indicaciones:

Answer 1

Indications

● Reduction and fusion of isthmic and degenerative lumbar spondylolisthesis

● Reduction and stabilization of lumbar burst and compression fractures

● Instability arising from primary or secondary neoplastic lumbar lesions

● Stabilization following wide lumbar decompression for spinal stenosis

● Revision surgery for symptomatic lumbar pseudarthrosis

● Stabilization after lumbar vertebral osteotomies

● Augmentation of anterior lumbar interbody fusion

● Scoliosis correction and stabilization. Lumbar Pedicle Screw Placement

Question 2

Contraindications of lumbar screw fusion

Answer 2

● Severe osteopenia and osteoporosis

● Inadequate pedicle size or morphology

● Fractured or diseased pedicles

● Presence of active infection such as vertebral osteomyelitis

Question 3

Cual es la densidad ósea asociada a aflojamiento y extracción del tornillo pedicular.

Answer 3

Bone density less than 0.45 g/cm has been associated with pedicle screw loosening and pullout.

Question 4

En que porcentaje aumenta la fijación del tornillo la penetracion de la corteza anterior del cuerpo vertebral y por qué no se recomienda?

Answer 4

Although penetration of the anterior lumbar body cortex enhances screw pullout strength by 20 to 25%, doing so increases the likelihood of vascular injury and is therefore not recommended.

Question 5

Cual es la profundidad recomendada de penetracion del tornillo en el cuerpo vertebral?

Answer 5

As a rule of thumb, the depth of insertion of the pedicle screw should be between 50 and 80% of the width of the anteroposterior diameter of the vertebral body on a lateral fluoroscopic view. This provides a safe zone for the screw to avoid penetrating the anterior vertebral body wall.