Combined arthrodesis may not enhance degenerative spondylolisthesis fusion rate

Posterolateral lumbar arthrodesis combined with interbody arthrodesis may add cost and time to the surgery.

The addition of interbody arthrodesis to posterolateral lumbar arthrodesis to treat L4-5 degenerative spondylolisthesis may just add expense and length of stay for a patient without any beneficial outcomes, according to a presenter at the International Society for the Study of the Lumbar Spine Annual Meeting.

Scott D. Boden, MD, of Emory Spine Center, in Atlanta, presented a study, that compared these two treatments based on their financial and clinical outcomes for patients with lumbar degenerative spondylolisthesis.

“In today’s environment, we must focus on which treatments obtain the best outcomes and at the greatest value for patients and society. This study demonstrates in the specific population studied that the addition of an interbody arthrodesis to a posterolateral arthrodesis could not be routinely justified on the basis of improved clinical outcomes and likely added cost,” Boden told Spine Surgery Today.

Combined vs alone

The investigators included in the study 179 patients with degenerative spondylolisthesis with an average follow-up of 38.7 months. Sixty-eight patients underwent posterolateral arthrodesis alone and 111 patients underwent posterolateral arthrodesis combined with an interbody arthrodesis.

Boden, who is Chief Medical Editor, Orthopedic Surgery for Spine Surgery Today, noted the study was designed to detect smaller than normal minimal clinically important differences between the two groups for SF-36, Oswestry Disability Index (ODI) and VAS pain scores.

“What you can see is for ODI and SF-36 PCS (physical health) and MCS (mental health scores) scores, there was no difference in the improvement of the posterolateral alone or the combined group. Both groups had significant improvement and they were comparable at 6 months and the most recent or longest follow-up. There was no significant difference in fusion success status at any time point between the two cohorts, but ultimately the final fusion results were 95% fused and 5% nonunion in both groups,” Boden said.

No significant differences

The patients in the posterolateral arthrodesis group had more levels that were decompressed than the combined group. However, patients in the combined group had more blood loss, longer surgical times and a higher drain output, according to Boden.

When Boden and colleagues adjusted the length of stay (LOS) findings for the number of levels that were decompressed in both groups, they found no statistically significant difference for LOS.

Bone morphogenetic protein was used frequently in both groups.

The financial results showed higher hospital charges in the combined group when the investigators controlled for LOS, increased patient age and Charlson comorbidity index. The cost differences ranged from $500 to $5,000, Boden said.

“But, at this sample size, that was not statistically significantly different. Also, in terms of cost per quality-adjusted life years [QALY]...it depends, based on what the LOS was, what the actual cost was, and by the time the LOS had reached 6 days from the outliers, clearly the cost per QALY was much lower in the posterolateral-only group,” he said.

The addition of interbody arthrodesis in the study did improve lordosis and sagittal balance by 1.5° compared to the posterolateral alone group.

Based on these results, Boden recommended the combination of these two procedures not be used for routine treatment of symptomatic degenerative spondylolisthesis. – by Robert Linnehan

Reference:
Boden SD, et al. Paper #58. Presented at: International Society for the Study of the Lumbar Spine Annual Meeting; June 8-12, 2015; San Francisco.

For more information:
Scott D. Boden, MD, can be reached at Emory Healthcare, Emory Orthopaedics and Spine Center, 59 Executive Park South, Atlanta, GA 30329; email: sboden@emory.edu.

Disclosure: Boden reports no relevant financial disclosures.