United States trends in lumbar fusion surgery for degenerative conditions.

Study Design: Retrospective cohort study using national sample administrative data.
Objectives: To determine if lumbar fusion rates increased in the 1990s and to compare lumbar fusion rates with those of other major musculoskeletal procedures.
Summary of Background Data: Previous studies found that lumbar fusion rates rose more rapidly during the 1980s than did other types of lumbar surgery.
Methods: We used the Healthcare Cost and Utilization Project Nationwide Inpatient Sample from 1988 through 2001 to examine trends. U.S. Census data were used for calculating age and sex-adjusted population-based rates. We excluded patients with vertebral fractures, cancer, or infection.
Results: In 2001, over 122,000 lumbar fusions were performed nationwide for degenerative conditions. This represented a 220% increase from 1990 in fusions per 100,000. The increase accelerated after 1996, when fusion cages were approved. From 1996 to 2001, the number of lumbar fusions increased 113%, compared with 13 to 15% for hip replacement and knee arthroplasty. Rates of lumbar fusion rose most rapidly among patients aged 60 and above. The proportion of lumbar operations involving a fusion increased for all diagnoses.
Conclusions: Lumbar fusion rates rose even more rapidly in the 90s than in the 80s. The most rapid increases followed the approval of new surgical implants and were much greater than increases in other major orthopedic procedures. The most rapid increases in fusion rates were among adults aged 60 and above. These increases were not associated with reports of clarified indications or improved efficacy, suggesting a need for better data on the efficacy of various fusion techniques for various indications.