1 Introduction topenlarge
MIS reduces the surgical trauma for the patient, potentially resulting in a quicker recovery while providing similar clinical mid to long term results.
In cases where neurological deficit is observed and compression of the spinal canal is assumed, decompression has to be performed. It should be understood that this is a step that can also result in deterioration of neurology unless very meticulously performed.
Decompression can be performed anteriorly or posteriorly. Posteriorly decompression can be indirect or direct.
Indirect decompression may be tried before performing direct decompression.
Please refer to Decompression techniques for a detailed discussion of indications for the posterior decompression techniques. ( Posterior decompression)
2 Closed reduction topenlarge
Primary reduction is performed by positioning of the patient onto a frame to create lordosis or kyphosis as needed by the fracture type and the level of the injury.
3 Reduction with pedicle screws (MIS) topenlarge
Due to the fact that bilateral instrumentation is necessary in all cases, all steps described below are repeated on the opposite side, unless described differently.
Pitfall: Multisegmental stabilization
In the thoracic spine, multisegmental stabilization is recommended, because reduction is more complicated and loss of mobility is less critical due to the relative rigidity of the thoracic spine.
If multisegmental stabilization is necessary, add screws in the adjacent caudal and cranial vertebrae.
Pedicle screw insertion
Pedicle screws are inserted into the vertebrae cephalad and caudal to the fracture level on both sides. Mono- or polyaxial top or side loading screws can be used in any combination. ( Pedicle screw insertion)
The amount of lordotic/kyphotic reduction is defined by the pre-bending of the rod. This restores the height of the vertebral body, especially in the anterior part.
Multiple attempts to bend the rod correctly might be necessary.
The rods are introduced to the distal screw heads on both sides and tightened.
The rod is then inserted into the proximal screw heads without tightening.
If it is decided to perform an indirect decompression, this is done at this stage. If indirect decompression proves to be insufficient, a direct decompression eg, posterior or transpedicular decompressions are undertaken. Refer to the Posterior Decompression techniques for detailed instructions. ( Posterior decompression)
4 Distraction topenlarge
Monoaxial toploading screws
Distraction of the monoaxial screws is performed using a distraction device. This restores the height of the vertebral body, especially in the posterior part.
Polyaxial toploading screws
Polyaxial toploading fixation should only be used if adequate closed reduction could be achieved.
Lordotic/kyphotic reduction is not possible with polyaxial toploading screws.
Distraction of the fractured vertebra using polyaxial screws is performed using a distraction device.
The screw heads are tightened with the inner nuts to secure the reduction achieved.
The final construct is shown from a lateral view.
5 Fusion top
Although fusion was routinely performed for all spinal fractures, its indications are now being restricted to fractures that are highly unstable.
Nonfusion fixations can be performed for A3, A4, and B1 type injuries. Fusion is routinely performed for A2, B2, B3 and all C injuries as they are unstable injuries with extensive soft tissue and ligamentous disruption.
If the surgeon plans for a fusion, the facet capsule is excised and the joint cartilage surfaces are denuded/curetted.
Pieces of bone graft (autograft, allograft) are inserted into the decorticated facet joint for fusion.