Implanting Expanding Cages to Reconstruct the Spine: Patient Cases
Expandable cages offer surgeons a vertebral body reconstruction solution. These cages combine rigid anterior (front) spinal column support, excellent fixation into the vertebral endplate, adequate room within the cage for bone graft, and generally unmatched ability for distraction (surgically create space) and sagittal (lordosis, standing upright) alignment.
A 64-year-old female with cervical myelopathy and kyphosis.
Preoperative lateral MRI
Postoperative cervical lateral x-ray
at 6 months after surgical reconstruction
Postoperative cervical anterior
posterior x-ray at 6 months
A 68-year-old female with vertebral osteomyelitis and progressive paralysis.
Preoperative lateral (side) CT scan
Preoperative lateral (side) MRI.
Postoperative lateral x-ray
Implanting the Expandable Cage
Following the vertebrectomy procedure, the surgeon prepares the endplates and measures the size of the defect. The size (diameter) of the endplate is determined. The cage is expanded close to the length needed so it can be easily inserted into the defect. After the cage is expanded, it is tightly packed with bone graft material (autologous, allograft). Next, the cage is inserted into the defect and positioned. When the cage is in the ideal position, it is held in place and expanded to engage or fix into the endplates.
The expandable cage can be adjusted for correct lordosis or kyphosis. The surgeon may perform further distraction. An x-ray taken during surgery confirms the expandable cage is properly implanted and secure. Once complete, there may be a few millimeters of space between the bone graft chamber and the endplate. This space is filled with more bone graft. Depending on the type of spinal reconstruction, expandable cages can be supplemented with anterior (front) and/or posterior (back) instrumentation.
The patient's progress is carefully monitored following surgery. Evidence of fusion will be checked by CT scan at six months and one year postop.
Unlike bone struts, bone graft movement is not an issue because expandable cages are rigidly fixed into the endplates. Bone graft settling is avoided because the expandable cage covers the edges of the vertebral endplates.
Expandable cages are a versatile important tool for spine surgeons who perform vertebral body reconstruction.