ABSTRACT
STUDY DESIGN: Case series report. OBJECTIVE: To evaluate the macroscopic and histologic appearance of bone after implantation of bone marrow aspirate on mineralized collagen fiber (Healos) at 12 to 24 months postoperative. SUMMARY OF BACKGROUND DATA: Numerous bone graft substitutes are currently used for spinal fusion. The success of these technologies is usually determined by radiographic visualization at 1-year or 2-year follow-up. Although x-rays and computed tomography scans are among the best tools to identify bone, interpretation of these images can still lead to error. METHODS: Six subjects with prior spinal fusion were reoperated for spinal implant removal. All subjects had reached at least 11-month follow-up from their initial spinal surgery. The graft material used in all fusion sites was bone marrow aspirate with Healos (BMA-H), except in a case where autograft was used on one side and BMA-H on the other. At implant removal, macroscopic appearances of the fusion sites were manually tested, photographed, and biopsies were taken and processed for routine histology. RESULTS: Macroscopic observations were critical to determine presence of mineralized or fibrous tissue. In the site implanted with autograft, fibrous tissue was observed macroscopically. This finding was confirmed by histology. In all sites implanted with BMA-H, solid bone was observed macroscopically. In 1 particular case, the newly formed fusion masses had a rectangular shape, reminiscent of that of the implanted strips. Histologically, BMA-H biopsies revealed mature cortico-cancellous bone. CONCLUSIONS: Published accounts of histologic evaluations of bone graft materials are uncommon, due to ethical and clinical limitations to harvesting tissue samples. Reoperations for instrumentation removal present rare occurrences when biopsies can be performed. In all cases, BMA-H implants resulted in solid, mature bone. These findings provide additional data on the effectiveness of BMA-H as a bone graft substitute for posterolateral fusion.
