Résumé
STUDY DESIGN: A randomized, controlled study OBJECTIVES: We wanted to investigate whether osteogenesis can be enhanced when a small amount of demineralized bone matrix (1 cc/segment) is mixed with local bone chips. SUMMARY OF LITERATURE REVIEW: Demineralized bone matrix (DBM) has been used for spinal arthrodesis. However, there are only a few reports about its use as a composite graft with local bone chips for posterior lumbar interbody fusion MATERIALS AND METHODS: Degenerative spine patients, who would normally be treated by decompression and posterior lumbar interbody fusion with using a pedicle screw system and one cage, were randomly, prospectively selected for whether they would be treated with using local bone chips mixed with 1cc of DBM (Group I: 15 patients and 19 segments) or local bone chips (Group II: 12 patients and 13 segments) for graft material. The sampling bias was investigated for gender, age, endocrine diseases, previous operation, habits (alcohol drinking, smoking), steroid medication, bone mineral density and the amount of local bone. The amount of bone formation was measured at 6 months after operation. On the sagittal and coronal reconstruction CT images, the bone formation outside of the cage was measured, and this was interpreted in a "blinded"fashion by 2 independent doctors who did not take part in the operations. RESULTS: There was no sampling bias between the 2 groups except for age (Group I= 65.3+/-7.1, Group II=58.9+/-6.0, p=0.010). The ratio of local bone chips and DBM was 5.98:1 in Group I. There was moderate concurrence between the 2 interpreters (kappa coefficiency= 0.494, p<0.001 for the sagittal plain images and kappa co-efficiency=0.467, p<0.001 for the coronal plain images) and Group I showed significantly more bone formation (p=0.003). CONCLUSION: DBM that is mixed with local bone chips, even with small amount, enhanced bone formation in the posterior lumbar interbody fusion. This is regarded to act as a graft enhancer to increase the fusion rate, even when using local bone chips for graft material, for the cases that show unfavorable conditions for fusion or for the cases that are prone to loosening of hardware.