Study design: Prospective trial.
Objective: To examine the difference in bone union and clinical results after one-, two-, and three-level instrumented posterolateral fusion surgery using a local bone graft.
Summary of background data: The iliac crest bone graft technique for lumbar posterolateral fusion surgery is widely used; however, donor site problems such as pain and sensory disturbance have been reported. Local bone has been used for fusion surgery; however, its reliability as a graft for multiple segments has not been fully reported.
Methods: One hundred twenty-two patients diagnosed with degenerated spondylolisthesis were divided into three groups [spondylolisthesis at 1 level (n = 42), at 2 levels (n = 40), and at 3 levels (n = 40)]. All patients underwent decompression and instrumented posterolateral fusion with a local bone graft. The amount of bone graft, proportion of patients with (rate) and duration of bone union, Visual Analog Scale (VAS) score, Japanese Orthopedic Association Score (JOAS), and Oswestry Disability Index (ODI) were evaluated before and 2 years after therapy.
Results: VAS score, JOA score, and ODI were not significantly different among the three groups before and after surgery (P > 0.05). Average amount of local bone graft used for one segment significantly decreased in proportion to the number of fusion levels (P < 0.05). The rate of bone union was 88% in the one-level group, 85% in the two-level group, and 62.5% in the three-level group, which was significantly lower than that in the one- and two-level groups (P < 0.05).
Conclusion: If one- and two-level posterolateral fusion were performed, the local bone graft technique provides a good and uniform bone union rate; however, for three-level fusion poor results were obtained because of an insufficient amount of local bone.