Las cajas intersomáticas son dispositivos cilíndricos o en forma de media luna, huecos y porosos que se colocan entre dos vértebras adyacentes en un segmento espinal después de extraer el disco dañado.
La caja puede ocupar todo el espacio del disco o solo la parte frontal (anterior) del mismo. Una cirugía de columna que justifica la extirpación del disco, como la fusión intersomática, por lo general utiliza jaulas intersomáticas.
La parte superior e inferior de una caja intersomática espinal están en contacto con los platillos vertebrales, la región de transición donde un cuerpo vertebral y un disco intervertebral interactúan entre sí.
La caja se llena con material de injerto óseo (extraído del cuerpo del paciente o sintetico) fusionando permanentemente las dos vértebras adyacentes del segmento tratado.
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Interbody cages are cylindrical or crescent-shaped, hollow, and porous metallic devices that are placed between two adjacent vertebrae in a spinal segment after removing the damaged disc. The cage may occupy the entire disc space or just the front (anterior) part of it. A spinal surgery that warrants removal of the disc, such as interbody fusion, usually uses interbody cages.
The top and bottom of a spinal interbody cage are in contact with the vertebral endplates—the transition region where a vertebral body and intervertebral disc interface with each other. The cage is filled with bone graft material (harvested from the patient’s body or obtained from another source) that grows over time and fills within the interbody space, permanently fusing the two adjacent vertebrae of the treated segment.
Interbody Cage Designs
The design of a cage typically depends on its material, placement, and technique used to deliver it into the interbody or disc space of the spine. A cage that covers more surface area of the vertebral endplates, such as a patient-specific 3D printed cage, helps achieve higher stability by decreasing the forces directly impacting the unsupported area(s) of the endplates.
Posterior interbody cages
Posterior interbody cages are made of the same materials and designs as anterior interbody cages but are placed into the disc space from the back of the spine.
Interbody Cage Placement
Most of the cages are placed in the front of the spine through an anterior lumbar interbody fusion (ALIF) surgery. The cages can be inserted through a small incision (mini-laparotomy) or with an endoscope (a small tube with a camera at the end that allows the surgery to be done through several one-inch incisions).
By far, the most popular approach for inserting titanium cages is through a mini-laparotomy, as the endoscopic approach is difficult and does not provide good visibility of the spinal segment. These cages may also be placed in the back of the spine through a posterior lumbar interbody fusion (PLIF) surgery.
Success Rates of Spinal Cages
Cages that remain in place, maintain their shape and height, and allow the bone graft to fuse are considered stable and successful. The stability of a cage is determined by measuring its subsidence—the degree of sinkage or caving in. A successful cage design is resistant to subsidence.
- Threaded cylindrical cages are associated with a fusion rate of 93% to 96%, with good or excellent pain improvement in 65% to 72% of cases. 6
- Cages made of PEEK (polyether ether ketone) typically have a higher rate of successful fusion, lower rate of subsidence, and a greater chance of restored disc height than cages made of titanium. 7
The cage’s design, material, and height; types of instruments used; and the surgeon’s expertise in placing the hardware in the spine are additional factors that contribute to its success.
BIBLIOGRAPHY https://www.spine-health.com/treatment/spinal-fusion/interbody-cages-spine-fusion