1 Introduction top
Based on CT and MRI imaging, a plan should be prepared to determine:
- The size and optimal location of implants used
- Whether spinal cord decompression is necessary and if so, the amount of tissue to remove in order to achieve sufficient spinal cord decompression
Every case will be unique, and we will here illustrate just one example.
Length of construct and cement augmentation
In patients requiring posterior lateral decompression, not requiring anterior column reconstruction, bilateral posterior pedicle screw fixation fixation with minimum fixation of at least one level above and below the involved segment should be used.
Short segment constructs lead to increased stress on the posterior implants increasing the risk of implant failure (screw pullout/fracture). The risk of implant failure may be decreased by cement augmentation of fenestrated screws and through reconstitution of the anterior column using cement augmentation of the pathological fracture.
Fixation of multiple spinal segments does not affect functionality in the thoracic spine due to the presence of rigid rib cage. Adequate screw purchase should be aimed for during initial surgery as revision surgeries are too demanding for these patients.
EmbolizationEmbolization procedures are recommended to reduce operative blood loss in hyper vascular tumors, especially for larger resections.
The preoperative neurological assessment must be carried out as described in the Neurological Evaluation.
2 Patient positioning and surgical approach topenlarge
3 Stabilization topenlarge
Pedicle screw insertion
Pedicle screws are inserted one or two levels above and below the tumor on both sides.
In cases of multilevel tumors or poor bone quality this construct can be extended.
In tumor patients achieving optimal screw purchase is even more important than in trauma patients to minimize risk of pullouts and reduce the number of levels involved.
Optimal pedicle screw purchase will, in order of importance, be achieved by:
- Selecting the largest possible screw diameter
- Selecting the longest possible screw
- Positioning of the screw under the cranial endplate
- Cement augmentation of the screw.
Rod contouring should mainly follow the curvature of the spine. Reducing preexisting deformities is typically not necessary and may lead to screw pull-out.
Rod insertion and fixation
The rod is inserted into the screw heads and the screw heads are tightened with the inner nuts.
If posterior decompression is performed only one rod is inserted to facilitate access to the spinal canal.
4 Fusion top
Life expectancy and performance status should be used to determine whether bone grafting is indicated.
For patients with good prognosis and a long life-expectancy, posterior fusion may optionally be performed using allograft and/or local autograft.
For nonfusion surgeries, the facet joint capsule is preserved during the entire procedure.
If the surgeon plans for a fusion, the facet capsule is excised, and the joint cartilage surfaces and posterior cortex are denuded/curetted.
Pieces of bone graft (autograft, allograft) are inserted into the decorticated facet joint for fusion.