Biological aspects to enhance fracture healing

Abstract

The ability to enhance fracture healing is paramount in modern orthopaedic trauma, particularly in the management of challenging cases including peri-prosthetic fractures, non-union and acute bone loss. Materials utilised in enhancing fracture healing should ideally be osteogenic, osteoinductive, osteoconductive, and facilitate vascular in-growth. Autologous bone graft remains the gold standard, providing all of these qualities. Limitations to this technique include low graft volume and donor site morbidity, with alternative techniques including the use of allograft or xenograft. Artificial scaffolds can provide an osteoconductive construct, however fail to provide an osteoinductive stimulus, and frequently have poor mechanical properties. Recombinant bone morphogenetic proteins can provide an osteoinductive stimulus; however, their licencing is limited and larger studies are required to clarify their role. For recalcitricant non-unions or high-risk cases, the use of composite graft combining the above techniques provides the highest chances of successfully achieving bony union.

Keywords: bone graft; bone substitute; fracture healing; non-union.

Figure 1

Autologous cancellous bone graft. (A) Cancellous graft harvested from the posterior iliac crest of the pelvis. (B) Graft harvested from the femoral intramedullary cavity using the RIA device.

Figure 2

Demonstration of the use of a synthetic material Greenbone block for defect treatment of the pelvic iliac crest. (A) Comparison between the tricortical iliac crest harvested for a pubic symphysis fusion with the synthetic greenbone block. (B) Intra-operative picture showing the greenbone next to the iliac crest defect prior to implantation. (C) Cutting with an electric saw the green bone block scaffold to appropriate length. (D) Implantation of the green bone by press fitting application within the iliac crest defect. (E) AP pelvic radiograph showing the integration of the green bone scaffold at 12-month follow-up (red arrow). (F) Pelvic 3D model showing incorporation of the green bone scaffold within the iliac crest defect (red arrow).

Figure 3

Application of calcium sulphate (stimulant) for the treatment of a tibial partial bone defect following debridement for late presentation of infection after union that required also removal of the plate. (A) Intra-opertaive picture showing the footprint of the plate after removal and the defect created following debridement of the infected bone area. (B) Intra-operative picture showing the application of stimulant to the defect area. (C) Intra-operative picture with covering of the defect area with stimulant. (D) AP and lateral tibial radiographs at 8 weeks showing that the defect is healing. (E) AP and lateral tibial radiographs 16 weeks later showing complete healing of the defect area.

Figure 4

Graft materials used for composite grafting. (A) Autologous graft. (B) Allograft. (C) Xenograft (Orthos). (D) BMP-7. (5) Bone marrow aspirate.

Figure 5

Treatment of a tibial defect utilising the polytherapy approach. Implantation of (A) concentrated bone marrow aspirate (progenitor cells), (B) BMP-7, and (C) RIA graft.

Figure 6

Demonstration of enhancing the biological properties of allograft material. (A) Femoral head allograft. (B) Processing of femoral head into bone chips. (C) Loading of allograft chips with autologous PRP and concentrated bone marrow aspirate. (D) Difference in the macroscopic appearance of the allograft after enhancement appearing more viable (red) possessing inductivity and cellularity.

Figure 7

Overview of materials used in the clinical setting based on their properties and limitations of their use.