Iliac Crest Bone Graft Harvest and Fusion Techniques

Approximately 250,000 bone grafting procedures are performed annually in the United States for spinal surgery. Anterior and posterior autologous iliac crest bone grafts (A/PICG) are commonly used in spinal surgery for spinal reconstruction and to obtain fusion. The clinical outcome of autologous iliac crest bone graft usage is more predictable compared to other grafting materials, including allograft, xenograft, and synthetic materials. The basic principles of an anterior cervical discectomy (ACD) or corpectomy (ACC) and fusion procedure includes decompression followed by restoration of the anterior column with a structural graft to achieve a biologic bony union. A structural cortical autologous bone graft has intrinsic stability and provides support while autologous cancellous bone provides cells and protein important for fusion success and a substrate for osteoconduction. However, it contributes no biologic support or structural stability. Autologous cancellous bone is frequently harvested from either the anterior or posterior iliac crest and is placed either anteriorly in a structural cage or posteriorly along the posterolateral cerical masses or intertransverse processes. Autologous tricortical AICBGs used in ACDF and ACCF procedures are widely used for this purpose throughout the civilized world. These structural grafts are used to achieve several goals, including load bearing following decompression, reconstitution of spinal alignment (lordosis), and a solid bony fusion. In posterior lumbar intertranverse fusions, a larger amount of bone graft is often needed as compared to a oneor two-level anterior spinal interbody procedure. This often requires significant (>45 cc) cancellous bone harvesting, potentially leading to postoperative donor site morbidity. Even with known morbidities due to its use, superior fusion outcomes using autologous iliac crest grafts have been well documented when compared to allograft or synthetic grafts. This is attributed to its superior osteoinductive and osteoconductive properties. Furthermore, a closer matching of the graft modulus to the host bone is obtained with autologous bone graft sources, which minimizes possible graft subsidence and cutout. An autologous bone graft source also obviates the risk of disease transmission and graft rejection compared to allograft bone. Unfortunately, harvesting iliac crest bone graft is not without a significant risk of donor site morbidity. Methods to decrease this morbidity have focused on either avoiding autologous graft harvesting or minimizing the amount of procured graft using smaller incisions and preserving as much of the cortical architecture of the native iliac crest. Minimal incision bone graft procurement strategies are primarily designed to minimize soft tissue disruption as well as to preserve as much as possible the cortical boundaries of the iliac crest harvest site. This may improve both shortand long-term outcomes related to bone graft donor site morbidity. This chapter discusses the pearls and pitfalls of harvesting the anterior or posterior iliac crest through various minimally invasive approach strategies.