Study shows 15% cumulative ASD rate with instrumented posterior lumbar spine fusion

Researchers who evaluated results of 511 patients undergoing posterior lumbar instrumented fusion for degenerative etiologies over a 23-year span at a single institution found a greater likelihood for adjacent segment disease or ASD to occur in patients with floating lumbar fusions.

“Our results demonstrate that patients undergoing instrumented fusion have statistically significant improved back pain (p < 0.001) and radiculopathy (p < 0.001) postoperatively. Patients who had floating lumbar fusions were statistically more likely to develop adjacent segment disease over time than those who had lumbosacral fusions incorporating the L5–S1 spinal segment,” Mohamad Bydon, MD, and colleagues wrote in the study.

For the retrospective study, Bydon and colleagues obtained data for patients undergoing instrumented lumbar arthrodesis for the treatment of degenerative lumbar disease at their institution from 1990 to 2013. The follow up averaged 39 months to 46 months.

“During this period, 212 patients (41.49%) experienced continued or recurrent back pain, and 148 patients (28.96%) experienced continued or recurrent radiculopathy. Forty-one (8.02%) and 31 (6.11%) patients had recurrent or continued motor or sensory deficits, respectively. Sixteen patients (3.13%) had continued bowel/bladder dysfunction. The cumulative rate of ASD development over time was 15.66% (80 patients),” Bydon and colleagues wrote.

The researchers reported that among the patients undergoing instrumented lumbar fusion, 256 patients received floating fusions and 255 patients received a lumbosacral fusion that included the sacrum distally.

“Because the rostral incidence did not statistically differ between the 2 cohorts, caudal ASD in the floating cohort likely accounts for the increased incidence of ASD. Although the heightened risk of ASD increased the reoperation rate in the floating cohort, the increased rate of postoperative radiculopathy contributed to reoperations in the lumbosacral cohort. Thus, the total reoperation rate is statistically the same,” Bydon and colleagues wrote. “Additional prospective studies may more clearly delineate the potential risk of ASD development as a function of fusion location, as well as long-term outcomes of instrumented posterolateral fusion.” – by Robert Linnehan

Disclosure: Timothy Witham is the recipient of a research grant from Eli Lilly and Company. Ziya Gokaslan is the recipient of research grants from DePuy Spine, AOSpine North America, Medtronic, the Neurosurgery Research and Education Foundation, Integra LifeSciences, and K2M. He receives fellowship support from AOSpine North America. He holds stock in Spinal Kinetics and US Spine. Ali Bydon is the recipient of a research grant from DePuy Spine. He serves on the clinical advisory board of MedImmune, LLC. Daniel Sciubba is the recipient of a research grant from DePuy Spine. He has consulting relationships with Medtronic, NuVasive, Globus, and DePuy.

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Source:

Bydon M. J Neurosurg Spine. 2014;doi: 10.3171/2013.12.SPINE13789.