Newswise — Driven by the increased use of surgical implant devices, rates of lumbar spinal fusion surgery for chronic back problems have increased in recent years, with no improvement in overall results and a significant increase in complications, reports a study in the Nov. 1 issue of the journal Spine.
Dr. Sham Juratli and colleagues of University of Washington, Seattle, analyzed state workers' compensation data on 1,950 lumbar (lower back) spinal fusion operations performed in injured workers from 1994 to 2001. Lumbar fusion surgery is an operation done to fuse together adjacent vertebrae in patients with certain types of chronic low back pain.
The number of patients undergoing lumbar fusion surgery increased, largely related to the introduction of new surgical devices, called "cages," in the mid-1990s. Cages are implanted devices placed to guide the growth of bone grafts for lumbar fusion. The proportion of lumbar fusion procedures performed with cages rose sharply—from less than four percent of procedures in 1994 to 58 percent in 2001.
However, the increased use of cages did not lead to improvements in the results of surgery. Two years after lumbar fusion, 64 percent of patients were still classified as disabled by the workers compensation board—this percentage was about the same for patients whose operation was done with cages or other implant devices, compared with "bone-only" implant procedures. Twenty-two percent of workers needed further back surgery within two years, with similar rates between groups.
Lumbar fusion with cages was also associated with an increased complication rate: twelve percent, compared to six percent for "bone-only" operations. The increase in complications even greater when cages were used along with other implants, and remained significant after adjustment for other factors.
The effectiveness of lumbar fusion surgery for chronic low back pain remains open to debate—some studies suggest that the results are about the same as with nonsurgical treatments. Nevertheless, as demonstrated by the Washington State data, the number of fusion procedures continues to increase, driven largely by the introduction of cages and other surgical devices.
Rapid increases in the these devices have not improved the outcomes of lumbar fusion, the new results suggest. "The use of cages [has been] associated with more complications than bone-only fusions without improvement in the disability or reoperation risk," Dr. Juratli and colleagues conclude. Although their study includes no economic analysis, the researchers question whether the increased costs of performing fusion surgery with cage devices are justified, given the lack of improvement in the results.
Another study in the same issue of Spine finds unexplained regional variations in the rates of lumbar fusion and other types of back surgery in the United States, raising concerns about the quality of the scientific evidence on back surgery in general and lumbar fusion in particular. "The scientific evaluation of outcomes for spine surgery has not kept up with the changes in operative techniques," conclude the study authors, led by Dr. James A. Weinstein, Editor-in-Chief of Spine.