Safe placement of pedicle screw in lumbar spine with minimum three year follow-up: a case series and technical note.

PURPOSE: This study aims to find a safe and easy-to-perform strategy for lumbar pedicle screw insertion based on anatomical landmarks.

METHODS: From March 2011 to January 2012, 74 patients underwent posterior lumbar interbody fusion or transforaminal lumbar interbody fusion using the new-designed screw insertion technique. During the operation, the entry site for screw insertion was on the outer edge of the superior facet joint, 4 mm downward from upper border of processus transversus. A connecting line between superior and inferior facet joints was used to determine the direction of screw insertion. Postoperative radiograph and computed tomography (CT) were taken routinely to show the position of the screws. Functional outcomes were evaluated using Oswestry Disability Index score, Japanese Orthopedic Association score, and Visual Analogue Scale, respectively.

RESULTS: Sixty-two patients (27 males and 35 females, average age 58.95 ± 8.45) finished the follow-up visit with an average of 46.03 months (36-60). The mean operation time and the blood loss were 169.60 ± 41.21 min and 489.52 ± 189.38 ml, respectively. A total of 274 pedicle screws were inserted following the new technique. According to Lothar Wiesner's classification, 11 screws (4.01%) caused minor violation into wall, two screws (0.73%) caused moderate violation, and other screws were in proper position.

CONCLUSION: A new-designed surgical strategy for pedicle screw insertion of lumbar spine was introduced and performed, which featured a series of original and easily distinguished landmarks. Clinical application demonstrated the safety and effectiveness of this novel technique for pedicle screw insertion.