Further Surgery for Adjacent Segment Disease Varies

Identified risk factors affect incidence, prevalence of ASD after lumbar fusions

MONDAY, Jan. 31 (HealthDay News) -- The annual incidence and predicted 10-year prevalence of further surgery for adjacent segment disease (ASD) after lumbar arthrodesis are 2.5 and 22.2 percent, respectively, though rates vary substantially based on identified risk factors, according to a study published in the January issue of The Spine Journal.

To determine annual incidence and risk factors for further surgery for ASD after posterior lumbar arthrodesis, William R. Sears, M.B.B.S., from the Royal North Shore Hospital in Sydney, Australia, and colleagues surveyed 912 patients who underwent 1,000 posterior lumbar interbody fusion procedures. The follow-up rate was 91 percent of patients.

The researchers found that further surgery for ASD after lumbar arthrodesis occurred in 13 percent of the cases at a mean time of 43 months, with a 2.5 percent mean annual incidence of surgery over the first 10 years. Patients who underwent fusions of three or four levels had a three-fold increased risk of further surgery compared with single-level fusions, and had a 10-year prevalence of 40 percent. They also found that the risk of further surgery for ASD in patients younger than 45 years of age was one-quarter that of patients older than age 60, and laminectomy adjacent to a fusion increased relative risk by 2.4 times.

"It is important that clinicians, their patients, and health economists have an accurate knowledge of the incidence and risk factors for the development of ASD after lumbar arthrodesis," the authors write.

Authors disclosed financial support from Medtronic and Paradigm Spine.

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