Introduction: The TLIF technique allows for more lateralized, one-sided and direct access to the intervertebral foraminal area without violation of the anatomical neural elements. Use of a supplemental interspinous process fixation plate as an adjunct to unilateral pedicle screws reduces the invasiveness of this technique. The entire contralateral facet is preserved for posterolateral bone graft without requiring the more lateral exposure for screw placement, making it less disruptive technique than traditionally performed bilateral pedicle screw placement for TLIF. The primary objective of the study was to analyze the radiographic outcomes in order to determine the effectiveness of this surgical technique.
Methods: A total of 102 patients underwent one- (n=78) or two-level (n=24) TLIF for painful degenerative disc disease from May 2008 to November 2010. The changes in disc height (DH), foraminal height (FH), overall lumbar lordosis and segmental alignment were measured were measured on lateral radiographs using the Cobb method. The available postoperative MRI scans were used for postoperative FH comparison between the instrumented and un-instrumented sides. The average follow-up time was 13.6 months (range, 1 – 34).
Results: The DH changes were not quite significant at L2/L3 (mean 3.5 mm; p = 0.07) and L3/L4 (mean 1.6 mm; p = 0.07) levels. Statistically significant DH changes were observed at L4/L5 (mean 1.3 mm; p = 0.01) and L5/S1 (mean 3.9 mm; p < 0.0001) levels. The changes in FH varied from the mean of -1.4 to 1.2 mm depending on the level, but none of these changes were statistically significant. There were also no statistically significant changes in overall lumbar lordosis or segmental alignment. The mean FH at the unilateral pedicle screw side was comparable to the un-instrumented side FH (16.1 mm vs. 17.6 mm; p = 0.3).
Conclusions: The TLIF with unilateral pedicle screws and interspinous process fixation plate technique does not significantly change or improve lumbar or segmental sagittal alignment, FH or DH, with the exception for the DH at L4/L5 and L5/S1 levels. There was no asymmetry in FH noted between the unilateral pedicle screw and un-instrumented side.
Patient Care: Surgical procedures that are less technically complex and invasive have reduced risk of complications, shorter hospital stays, decreased blood loss, operative time and faster recovery.
Learning Objectives: The participants will be able to appreciate the advantages of this less invasive approach presented.