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Definition

Reduced viability of the graft, defined as death of cells within the graft itself, affects integration of the graft into the host bed.

Risk factors

 Suboptimal handling of the graft

 Prolonged time between harvesting and implantation of the graft

 Lack of a second surgical team to harvest the graft

Pathogenesis

Reduced viability of the graft results from a combination of prolonged time between harvesting and implantation of the graft, dehydration or compaction of the graft, or exposure of the graft to air, saline‐soaked sponges, or antibiotics prior to implantation. Reduced cell survival is attributed to a combination of mechanical damage, desiccation, or osmotic challenge, depending upon the circumstances [10, 11].

Prevention

Cell survival may be maximized by several techniques during harvesting and implantation. A separate surgical team in addition to the surgeons repairing the fracture is advantageous, in order to harvest the cancellous bone graft while the surgical procedure is begun to reduce lag time between harvesting and implantation.

It is recommended to have blood‐soaked sponges ready to store the harvested bone or marrow following collection and prior to implantation (Figure 10.1). Blood may be obtained via intravenous catheter from the jugular or cephalic vein. Exposure of graft tissue to air, coverage with saline‐soaked sponges, or exposure of the graft tissues to antibiotics during harvesting should be avoided. Aseptic technique during implantation is essential for successful incorporation of the graft.

Figure 10.1 Loosely arranged cancellous bone graft in blood‐soaked sponge following collection from tuber coxae.

The bone graft material should be lightly packed into the recipient site to allow for appropriate oxygenation of the graft and to reduce mechanical damage to the cells [1, 10]. Osteogenesis occurs as a result of the activity of viable osteoblasts on the surface of the bone graft. Loosely arranged bone grafts are more desirable due to the greater surface area created, with more living cells available resulting in greater osteogenic activity. Avoiding dehydration and compaction of the bone graft results in a greater number of surviving cells and improved viability of the graft [8].

Diagnosis

Reduced viability of the bone graft may contribute to lack of incorporation of the graft into host tissue, resulting in prolonged fracture repair or increased rate of fracture repair failure. However, lack of viability of the graft itself may not be apparent unless infection of the recipient site occurs or fracture repair failure occurs postoperatively as a result of implant fatigue. Diagnostic imaging (e.g. radiography, ultrasonography or CT) may be utilized to recognize infection or fracture repair failure earlier if indicated based upon clinical signs.