Bone regeneration: current concepts and future directions

Bone regeneration is a complex, well-orchestrated physiological process of bone formation, which can be seen during normal fracture healing, and is involved in continuous remodelling throughout adult life. However, there are complex clinical conditions in which bone regeneration is required in large quantity, such as for skeletal reconstruction of large bone defects created by trauma, infection, tumour resection and skeletal abnormalities, or cases in which the regenerative process is compromised, including avascular necrosis, atrophic non-unions and osteoporosis. Currently, there is a plethora of different strategies to augment the impaired or 'insufficient' bone-regeneration process, including the 'gold standard' autologous bone graft, free fibula vascularised graft, allograft implantation, and use of growth factors, osteoconductive scaffolds, osteoprogenitor cells and distraction osteogenesis. Improved 'local' strategies in terms of tissue engineering and gene therapy, or even 'systemic' enhancement of bone repair, are under intense investigation, in an effort to overcome the limitations of the current methods, to produce bone-graft substitutes with biomechanical properties that are as identical to normal bone as possible, to accelerate the overall regeneration process, or even to address systemic conditions, such as skeletal disorders and osteoporosis

The Synergistic Effect of Autograft and BMP-7 in the Treatment of Atrophic Nonunions

Combining autologous bone graft and recombinant human bone morphogenetic protein-7 (BMP-7) to treat long-bone fracture aseptic atrophic nonunions theoretically could promote bone healing at higher rates than each of these grafting agents separately. We retrospectively reviewed prospectively collected data on patient general characteristics, clinical outcomes, and complications over 3 years to determine the healing rates and the incidence of complications and adverse events of this “graft expansion rationale.” There were 45 patients (32 male) with a median age of 43 years (range, 19–76 years). Minimum followup was 12 months (mean, 24.5 months; range, 12–65 months). There were seven humeral, 19 femoral, and 19 tibial nonunions. The median number of prior operations was two (range, 1–7). All fractures united. Clinical and radiographic union occurred within a median of 5 months (range, 3–14 months) and 6 months (range, 4–16 months), respectively. Thirty-nine (87%) patients returned to their preinjury occupation at a mean of 4.2 months (range, 3–6 months). The median visual analog scale pain score was 0.9 (range, 0–2.8; maximum 10), and the median functional score was 86 (range, 67–95; maximum 100) at the final followup. BMP-7 as a bone-stimulating agent combined with conventional autograft resulted in a nonunion healing rate of 100% in these 45 patients