Outcome of local bone versus autogenous iliac crest bone graft in the instrumented posterolateral fusion of the lumbar spine

Study Design. Retrospective, comparative study of clinical and radiologic outcome with independent, blinded observer. Objectives. To compare the clinical and radiologic outcome of instrumented posterolateral lumbar fusion using local bone versus autogenous iliac crest bone graft (ICBG). Summary of Background Data. There is no published report of outcome of posterolateral spinal fusion using local bone alone for degenerative disorders of the lumbar spine. Materials and Methods. Seventy-six cases (male 26, female 50) of spinal stenosis, operated during 1996 and 1997 by the senior author, were reviewed. All the cases had decompression and posterior spinal fusion with pedicle screw instrumentation. Forty cases had only local bone graft obtained from decompression, morselized in a bone mill, and 36 cases had autogenous ICBG. Mean age was 60 years (range, 27-83 years). Fusion was performed at one level in 51 (67%), two levels in 16 (21%), three levels in 5 (7%), and four or more levels in 4 cases (5%). Minimum follow-up was 2-years ( mean, 28 years; range, 24-72 months). An independent, blinded radiologist rated plain radiographs as fused, indeterminate, or nonunion. Results. There was no difference in age, sex, and diagnosis between the two groups. Overall fusion rate was higher in the ICBG group (75%, 27 of 36) compared with the local bone group (65%, 26 of 40) but not significantly different (P = 0.391). Analyzed separately according to the number of fusion levels, the local bone group achieved similar fusion rate (similar to 80%) in single-level fusion but a much smaller fusion rate in multilevel fusion (20% vs. 66%, P similar to 0.029) compared with the ICBG group. Mean improvement in the Oswestry Disability Inventory was 36% in the local bone group and 32% in the ICBG group. There was no significant difference in overall clinical outcome between the two groups. There was no correlation between fusion status and clinical outcome. Blood loss and hospital stay were significantly less in the local bone group; however, blood loss was more significantly related to the sum total number of segments undergoing decompression and fusion. Conclusions. Use of local bone graft alone achieved a similar fusion rate in single-level fusion but a much smaller fusion rate in multilevel fusion compared with the ICBG group. Local bone graft alone achieved a similar clinical outcome but less morbidity irrespective of number of fusion level.