Complications From Complete Posterior Only Correction Of High Grade Spondylolisthesis: A Comparison Of Techniques
Complications from high grade spondylolisthesis reduction can include neurologic deficit, construct failure, screw pull-out, pseudarthrosis, and prolonged operative times. Anatomic restoration would be preferable when the complication rate is low. The Edwards technique has been very effective in reducing high grade spondylolisthesis. A variation in this technique been developed to decrease these complications.
This study was undertaken to compare the complication rate with the Edwards technique to a modified technique using a rigid construct with reduction capability.
Comparison of a prospective treatment group to a retrospective review of similar patients treated with the Edwards construct.
Fifteen consecutive patients average age 17 (13-34 yrs) with high grade spondylolisthesis were surgically treated by the same surgeon. Eleven were treated with the Edwards technique and followed 6years (4–10 yrs). Four were treated with a rigid construct using screws with a pivoting reduction post, and prospectively followed 3 years (2–4 years). Slip severity included grade 5 = 7, grade 4 = 2, and grade 3 = 6 patients. Two patients had acute cauda equina syndrome, one had chronic bladder urgency, and 1 had complete foot drop.
Oswestry, Visual Analog pain Scores (VAS), pain medication use, and work status were followed for the rigid construct group. Patient satisfaction rating, VAS scores, medication use, and work status were followed in the Edwards group.
All patients underwent Gill laminectomy and full posterior instrumented reduction and fusion from L4 or L5-S1 without anterior surgery. Sacral dome osteotomies were performed in grades 4 and 5. Both the rigid and the Edwards constructs applied corrective forces of distraction, sacral flexion, and posterior translation by gradually pulling the L5 vertebra into sagittal alignment. Edwards constructs utilized lateral S1 and S2 alar screws, ratcheted stainless rods, and semi-rigid fixation. The new constructs used S1 pedicle screws and S2 alar or iliac screws, smooth 5.5mm titanium rods, and rigid fixation.
Full correction was achieved in all cases by the application of reduction forces through the instrumentation. All 3 patients with cauda equina syndrome recovered. New neurologic deficits occurred in 2/7 patients with spondyloptosis, 1 unilateral footdrop and one bilateral mild (4/5) quad weakness. One with pre-op footdrop failed to improve. In the rigid implant group, there were no cases of implant failure or screw pullout and the average operative time was 8 hours. In the Edwards group, 2 infections, 2 nonunions with construct loosening, and 2 had S2 screw pullout requiring revision, and average operative time was 11 hours. Excluding the hardware failure patients, the functional outcomes, VAS pain scores, and pain medication use are similar in the two groups, showing improved pain and function.
Though these numbers are small, it does appear that the full reduction capability of the Edwards technique can be achieved with improved fixation (rigid vs. semi-rigid, S1 pedicle vs. alar screws, optional iliac screws) and easier assembly (decreased OR time). The new rigid construct with screws containing the pivoting reduction posts appears to be an easier alternative to the Edwards technique for reducing high grade spondylolisthesis.