Study design: Retrospective case-control study.
Objective: To evaluate specific functional disabilities after short- and long-level lumbar fusion.
Summary of background data: The Oswestry Disability Index (ODI) cannot represent all types of functional disabilities observed after lumbar fusion and a region-specific Functional Disability Index (SFDI) is necessary.
Methods: We examined the differences in postoperative functional disability between 81 patients who underwent ≥3-level lumbar fusion (group I) and 70 age- and sex-matched patients who underwent one- or two-level lumbar fusion (group II). The ODI and Visual Analogue Scale (VAS) were assessed pre- and postoperatively. The SFDI was assessed after lumbar fusion. We evaluated intergroup differences in postoperative VAS, ODI, and SFDI scores during 3-year follow-up. Each mean score was evaluated separately for the 10 ODI and the 12 SFDI items, and we evaluated the changes observed in these scores over the 3-year follow-up.
Results: The mean intergroup preoperative ODI and VAS scores were similar. The mean postoperative intergroup VAS scores were similar; however, the mean postoperative ODI and SFDI scores were significantly higher in group I than in group II at 1-year (P<0.001, P<0.001, respectively) and 3-year follow-up (P = 0.037, P<0.001, respectively). Among 10 ODI items, group I showed significant disability with regard to six items at the 1-year follow-up compared with group II, but only showed significant disability with regard to one item at the 3-year follow-up. Among the 12 SFDI items, group I showed significant disability with regard to all 12 items at 1-year follow-up compared with group II, as well as significant disability with regard to nine items at 3-year follow-up.
Conclusion: The SFDI is more sensitive than the ODI in assessing functional disabilities based on the levels of fusion. Most SFDI items indicated continued significant disability in patients with long-level lumbar fusion even 3 years postoperatively.
Level of evidence: 3.