Percutaneous pedicle screw fixation (PPF):
For a degenerative spondylolisthesis case, a blunt probe is inserted through the pedicle and into the vertebral body. Once the pedicle canals are prepared and the screw length determined, the screws are sequentially inserted.
PPF can be performed after induction of general anesthesia. Thereafter, the patient is positioned prone on top of chest rolls with the abdomen free. A C-arm fluoroscopy device is used for guidance of percutaneous screw placement. A 15-mm-long incision was made for each screw at the appropriate skin entry point. A 14G vertebroplasty needle was inserted toward the pedicle and vertebra body and then the stylet replaced by 200-mm-long K-wire. A series of sequential dilation was performed along a K-wire and a 16-mm-diameter tunnel sleeve was inserted. The pedicles were tapped and then K-wire removed. Uncannulated screws can easily be placed as the tapped bone guided its passage. A soft tissue tunnel which connected two pedicle screw heads was made using a bended passer, and the pedicle screws were connected with bended round rod through the soft tissue tunnel. Final tightening of the pedicle screw-rod constructs were given under the fluoroscopic guidance. While tightening a screw-rod construct the remaining screw path was used to give antitorque and some compression force. Just one deep stitch was needed at each screw entry incision.
Although conventional fluoroscopy can be used for this purpose, it has certain disadvantages: the inability to visualize more than one plane of view at a single time (when using a single fluoroscope), the ergonomic challenges of working around a C-arm, and radiation exposure. It is important to check that adequate AP and lateral fluoroscopic images of the lumbar spine can be obtained before preparing and draping the patient.
Compared to open techniques, the presumed benefit of the percutaneous technique is avoidance of muscular tendon detachment, elimination of largescale muscle retraction, diminished postoperative pain, less blood loss, and improved cosmetic result.