Macroscopic and histologic analyses of de novo bone in the posterior spine at time of spinal implant removal.
METHODS
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.


BACKGROUND
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.
Birch
Nick
N
Spinal Clinic, BMI Three Shires Hospital, Northampton NN1 5DR, UK. nickbirch@doctors.org.uk
D'Souza
Winster L
WL
D000293:Adolescent; D000328:Adult; D016026:Bone Marrow Transplantation / Q000379:methods*; D001861:Bone Regeneration / Q000502:physiology*; D002113:Calcification, Physiologic / Q000502:physiology; D005260:Female; D006085:Graft Survival / Q000502:physiology*; D006801:Humans; D016268:Internal Fixators / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods; D019736:Prostheses and Implants / Q000009:adverse effects; D012086:Reoperation; D013122:Spinal Diseases / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods*; D013131:Spine / Q000166:cytology / Q000502:physiology / Q000601:surgery*; D014182:Transplantation, Autologous / Q000009:adverse effects; D016896:Treatment Outcome; D055815:Young Adult