The use of bone allografts in the spine.

Bone allografts are commonly used in spinal surgery. Structural allografts placed anteriorly in the spine may be used as interbody grafts or as strut grafts spanning multiple segments. Posterior allografts are used to supplement autologous bone for spinal fusions in patients who lack sufficient host bone and to avoid significant donor site morbidity. In this paper the authors review their experience with allograft bone in spine surgery and the results reported in the literature. In the anterior cervical spine, interbody allografts have been used most successfully in single-level fusions. For thoracolumbar deformity, posterior allograft with instrumentation gives satisfactory results in pediatric patients but yields inferior results in adults unless it is combined with an anterior fusion. Fresh-frozen allograft bone has been shown to have higher fusion rates than freeze-dried allograft; ethylene oxide-sterilized allograft has shown uniformly poor results. Structural allografts have been useful for thoracolumbar deformity in both interbody and strut-grafting procedures. In the lumbar spine, allograft has a limited role in posterolateral fusion. For anterior interbody fusions, structural allografts, such as femoral ring allografts, have been used successfully to maintain intervertebral distraction, despite delayed incorporation. Successful use of allograft bone in the spine is dependent on the type of allograft bone used, its anatomic site of fusion, and the age of the patient.