Results of lumbosacral distraction spondylodesis for the treatment of spondylolisthesis, failed-back syndrome, and lumbar instability

Pedicle screw fixation for isthmic spondylolisthesis: does posterior lumbar interbody fusion improve outcome over posterolateral fusion?

OBJECT

Posterolateral fusion involving instrumentation-assisted segmental fixation represents a valid procedure in the treatment of lumbar instability. In cases of anterior column failure, such as in isthmic spondylolisthesis, supplemental posterior lumbar interbody fusion (PLIF) may improve the fusion rate and endurance of the construct. Posterior lumbar interbody fusion is, however, a more demanding procedure and increases costs and risks of the intervention. The advantages of this technique must, therefore, be weighed against those of a simple posterior lumbar fusion.

METHODS

Thirty-five consecutive patients underwent pedicle screw fixation for isthmic spondylolisthesis. In 18 patients posterior lumbar fusion was performed, and in 17 patients PLIF was added. Clinical, economic, functional, and radiographic data were assessed to determine differences in clinical and functional results and biomechanical properties. At 2-year follow-up examination, the correction of subluxation, disc height, and foraminal area were maintained in the group in which a PLIF procedure was performed, but not in the posterolateral fusion-only group (p < 0.05). Nevertheless, no statistical intergroup differences were demonstrated in terms of neurological improvement (p = 1), economic (p = 0.43), or functional (p = 0.95) outcome, nor in terms of fusion rate (p = 0.49).

CONCLUSIONS

The authors' findings support the view that an interbody fusion confers superior mechanical strength to the spinal construct; when posterolateral fusion is the sole intervention, progressive loss of the extreme correction can be expected. Such mechanical insufficiency, however, did not influence clinical outcome.

Posterior fusion and implantation of the SOCON-SRI system in the treatment of adult spondylolisthesis

Surgery for adult patients with lumbar and lumbosacral spondylolisthesis is reserved for those with intractable radiculopathy, claudication, or symptomatic spinal instability. Internal fixation, in which posterior fusion, transpedicular screw fixation, and implantation of titanium devices are performed, has been advocated to improve fusion rates and clinical results. Fourteen consecutive patients with Grade II to III lumbar and lumbosacral spondylolisthesis who underwent posterior decompression, reduction, autologous posterior facet joint arthrodesis, and SOCON-SRI implantation are retrospectively reviewed.

All patients underwent complete preoperative clinical and neuroradiological evaluation. Treatment consisted of posterior decompressive surgery and implantation of the SOCON-SRI system (transpedicular screws, prebent longitudinal rods, and one locking-screw clamps). Distraction of the interbody space and rotation were performed to achieve an optimum spinal realignment. The facet joints were fused by using autologous bone graft. The authors obtained detailed clinical, functional, economic, and neuroradiological follow-up data for up to 14 months (range 8–18 months).

The efficacy of the treatment was evaluated by comparing pre- and postoperative data. Pain was decreased in all cases, neurological dysfunction ameliorated in 50%, and functional and economic status was improved in 78% and 100%, respectively. No cases of fusion failure or instrumentation-related complications occurred. The authors describe their results of treating patients with spondylolisthesis in the light of the rationale for surgery and the more recent pertinent literature.

Clinical efficacy of pedicle instrumentation and posterolateral fusion in the symptomatic degenerative lumbar spine

Eighty-five patients with degenerative lumbar spine disease and radiologic evidence of instability, all older than 50 years (mean age 63.4 years), underwent transpedicular lumbar CD-spondylodesis and posterolateral fusion between 1987 and 1992; 30 of them (mean age 60.8 years) had posterior lumbar interbody fusion (PLIF) additionally. The patients were followed up for a mean period of 32 months. Of these patients, 86% improved with respect to their pain symptoms, but only 46% showed a good to excellent overall result. Patients with fair and poor outcomes had had significantly more operations on the lumbar spine (P < 0.001), had a greater extent of preoperative lumbar kyphosis (P < 0.05), had a larger preoperative motor weakness (P < 0.05), and had less vertebral slips (P < 0.01) than patients with good to excellent outcomes. Patients treated with transpedicular spondylodesis plus PLIF did not make any better progress than those with transpedicular fusion alone. By the 6-month follow-up a significant difference in the clinical outcome was already apparent (P < 0.001), making an improvement of a then fair or poor result unlikely.