Abstract
Introduction
Despite the benefits of minimally invasive spine surgery (MIS), inherent risks to the patient and surgeon exist. Numerous studies demonstrate increased radiation exposure with MIS secondary to the need for increased fluoroscopy, thereby increasing the risk of cataracts and malignancy. Additionally, inadvertent advancement of standard guide wires through the vertebral body can occur, placing vital ventral structures at risk. This study evaluates the benefit of utilizing a novel split-tip guide wire for percutaneous pedicle screw placement.
Methods
A total of 30 consecutive cases of MIS transforaminal lumbar interbody fusion (TLIF) at L5–S1 were retrospectively evaluated. Group 1: Standard straight guide wire, 15 patients; group 2: split-tip guide wire, 15 patients. Except for the type of guide wire utilized, the same operative technique was used in each case, including bicortical S1 screw fixation. Total fluoroscopy time, radiation dosage, operative time, and complications were evaluated.
Technique: (1) S1 pedicles are cannulated with standard Jamshidi needles. (2) Y-wires are placed through Jamshidi needles. (3) A cannulated Steffee probe cannulates the distal sacral promontory over the Y-wire. (4) The Steffee probe is retracted 50% and Y-wire is repositioned (Y-wire design prevents inadvertent advancement through sacral promontory). (5) The proximal S1 pedicle can be tapped over the Y-wire (not required). (6) Cannulated pedicle screws are placed over the Y-wire, engaging the distal sacral promontory for bicortical S1 purchase.
Results
Mean total fluoroscopy time per case for group 1 was 231.1 seconds versus 154.2 seconds for group 2 (p = 0.017). Mean radiation dosage for group 1 was 16.22 versus 8.69 rads in group 2 (p < 0.001). There was no significant difference in operative time (p = 0.18). Inadvertent advancement of two S1 guide wires occurred in two different patients in group 1. Postoperative abdominal CT scans with contrast were negative.
Conclusion
Utilizing a split-tip guide wire for percutaneous pedicle screw placement significantly decreased fluoroscopy time by 33% and radiation dosage by 46%. Cannulating the sacral promontory allows for bicortical S1 screw purchase, but removes the mechanical stop preventing inadvertent guidewire advancement. The split-tip guidewire may prevent wire advancement and decreases the need for fluoroscopic surveillance. This, in turn, reduces the risk of injury to structures ventral to the spine, while reducing the exposure to harmful radiation.