When bone graft is taken from the patient's own body as part of a spinal fusion surgery, it is in essence an additional surgery done at the same time as the spinal fusion surgery.
Bone Harvest Approaches
Taking bone from the front of the ilium generally results in more pain and disability than harvesting bone from the back. The most significant pain and disability results when large pieces of bone are harvested from the front. New techniques have been developed for harvesting graft through smaller incisions in an attempt to decrease donor site pain. Minimizing the amount of soft tissue trauma and the use of local anesthetics in bone graft harvest helps to decrease post-operative pain.
Harvesting bone from the back of the pelvis can often be done through the same incision used for the spinal fusion by dissecting between the tissue planes, or through a separate skin incision.
Factors That Influence Post-operative Pain and Morbidity
Regardless of the approach used to harvest the bone graft, there are several potential risks with this part of the spinal fusion surgery, including:
- The sensory nerves that exit in this region (cluneal nerves) may be cut, bruised, or stretched. Injury to these nerves can result in persistent pain. When harvesting bone from the front of the pelvis the nerve at risk is the lateral femoral cutaneous nerve, which supplies sensation to the anterior thigh. Injury to this nerve can also result in significant pain (meralgia paristhetica).
- Blood vessel injury can cause significant blood loss and hematoma formation.
- Violation of the sacroiliac joint (where the pelvis attaches to the spine) can occur during posterior iliac crest harvest (when bone graft is taken from the back).
- Fractures of the front most portion of the ilium (ASIS - anterior superior iliac spine) can result if the graft is taken too close to the anterior iliac spine.