Stem Cells in Bone Grafting: Trinity Allograft with Stem Cells and Collagen/Beta-Tricalcium Phosphate with Concentrated Bone Marrow Aspirate

The concept of osteoinduction and osteoconduction has been furthered with the concept of osteogenesis; Siegel and colleagues(13) discuss the scaffolding of the tricalcium phosphate/collagen for osteoconduction, the growth factors in the concentrated bone marrow aspirate for osteoinduction, and the stem cells in the concentrated bone marrow aspirate as further stimulus for osteogenesis. The scientific studies have led to various conclusions regarding the best combination of substrate and biologic agent. Castellani and colleagues(14) found no improvement in bone ingrowth between TricOs (Baxter AG, Vienna, Austria) and Collagraft (Zimmer, Inc, Warsaw, IN, USA), both tricalcium phosphates with a bioactive matrix, when bone marrow aspirate was added to the ceramics filling a rabbit femoral defect. In contrast, Liu and colleagues(15) found that human bone marrow stromal cells greatly augmented the bone formation in beta-tricalcium phosphate scaffolds when implanted into mice. Hing and colleagues(16) discussed finding in spine grafting that some of the tricalcium phosphates might be degraded early, thus decoupling bone regeneration and resorption and leading to incomplete bone repair. Their studies led to conclusion that a silicone-calcium phosphate led to a more stable osteoconductive scaffold, which thus better supported angiogenesis and bone apposition. Recent spine work has confirmed clinical success of the beta-tricalcium phosphate/collagen combination. The beta-tricalciunn phosphate has been used clinically with allograft(17) and autograft(18,19) for lumbar interbody fusion. The beta-tricalcium phosphate has been compared clinically with iliac crest autograft for posterior correction of scoliosis with equivalent fusion and less morbidity.(20) This entire issue could be devoted to comparing and contrasting the myriad of studies available; a consensus has yet to be clearly made as to the best combination of materials for bone grafting and augmentation. The authors have found great clinical success using the material in the foot and ankle, especially with concentrated bone marrow aspirate, and clinical outcome studies are under way.