Background
The current gold standard in thoraco-lumbar fusion surgery of the spine is posterolateral arthrodesis using autologous bone graft from the iliac crest in addition to instrumentation. Although autologous bone grafts provide ideal biological properties, graft harvesting may cause severe donor site morbidity. Therefore, spine surgeons increasingly tend to use allogenic bone graft as osteoconductive and osteoinductive carriers enhancing solid fusion without disadvantages of graft harvesting. Demineralised bone matrix (DBM) has shown to be a reliable alternative in terms of its fusion capacities in several animal models as well as in clinical investigations in humans. While histological performance of DBM was extensively investigated in animal fusion models, only few ex vivo studies were reported proving efficacy of this generally very expensive material. These studies dealt either with dental surgery procedures or idiopathic scoliosis in a child, whereas no ex vivo investigation was reported focusing on adult spine surgery. To our knowledge, the present study is the first report of histological performance of DBM in a consecutive series of patients who underwent posterolateral fusion of the spine. The goal of our investigation therefore was to clarify whether DBM incorporates to the surrounding bone or not. The hypothesis was set up that transformation of DBM is related to its time in situ ("dwell time").