Clinical Series of Spondylolisthesis Reductions
The isthmic defects were located in the L5 segment in 19 patients, while the Spondylolisthesis was at the L4-5 segment in three patients. All patients underwent a Gill procedure at the involved segment and aggressive débridement of the pars interarticularis defects. During the same operative session, the patients underwent reduction of their Spondylolisthesis, utilizing the SOCON reduction instrumentation followed by SOCON pedicular instrumentation, and posteriorlateral fusion, utilizing iliac or local autogenous bone. In addition, all patients except one 12-year-old girl were treated with an interbody graft at the Spondylolisthesis site; there were 14 posterior lumbar interbody fusions and 7 anterior lumbar interbody fusions (see Figs. 8 and 9).
A typical patient in this series with a nicely reduced
grade 2 Spondylolisthesis. a) Preoperative X-ray; b) postoperative X-ray
Figure 9a, b:
Grade 3 isthmic Spondylolisthesis patient with a safe near-anatomic
reduction utilizing the SOCON Spondylolisthesis Reduction Instrumentation.
a) Preoperative X-ray; b) postoperative X-ray
Follow-up ranged from 3 to 18 months (average 10 months). Anatomic reduction of the Spondylolisthesis was defined as a reduction with 3 mm or less remaining Spondylolisthesis. Based on this definition, 19 of the 22 patients demonstrated anatomic reduction at last follow-up. There was only one case of instrumentation failure, in a 12-year-old girl with a grade 3 L5/S1 Spondylolisthesis who had undergone isolated posterior-lateral fusion after anatomic reduction without an interbody graft. The reduction was lost when the instrumentation failed. This patient underwent repeat reduction and instrumentation revision followed by an anterior lumbar fusion. At 18 months of follow-up she is complaining of back pain, and radiographs reveal maintenance of her anatomic reduction at L5/S1, but a grade 1 degenerative Spondylolisthesis has developed at L4–5. One patient developed an L5 pedicle fracture during reduction and it was elected to abandon the reduction and proceed with an in-situ fusion. Finally, there was a 39-year-old woman with a grade 3 Spondylolisthesis who underwent anatomic reduction during her procedure; however, the L5 roots appeared excessively tight and it was elected to lessen her reduction to 50 %.
Intraoperative complications, including one dural tear, were treated with repair without postoperative sequelae. Average blood loss was 422 cc (range 100–725 cc) with an average operative time of 3 hours and 45 minutes (range 152–295 minutes). There were no wound infections. One urinary tract infection developed one week after the patient was discharged from the hospital.
There was no neurologic deterioration in any patient in response to the reduction. All patients experienced relief of their preoperative radiculopathy, with the exception of a 47-year-old woman who reported continued preoperative right L5 radicular leg pain at 12 months followup. All patients demonstrated complete resolution of their preoperative neurologic deficits. The above-mentioned patient with preoperative bladder symptoms reported immediate resolution of her symptomatology following her procedure. 20 of the 22 patients reported marked improvement in their preoperative symptoms and were pleased with their result.
Solid fusion was defined as trabeculated bone across the interbody graft with no motion seen at the time of superimposition of flexion and extension films obtained at their 6 months followup. Posterior-lateral bone formation was variable and was not used in the classification of arthrodesis. 16 patients were followed up for a minimum of 6 months, and 15 of these exhibited a solid fusion. The remaining patient exhibited faint radiolucent lines around his interbody graft at 12 months follow-up, but complete stability was noted on the flexion and extension films.
Backup, 2-2002, Aesculap AG & Co. KG Tuttlingen