Introduction
Evidence & Methods
With the introduction of bone graft substitutes, the morbidity of iliac crest bone graft harvesting for lumbar fusions has become an area of interest. Some have suggested that backfilling of iliac crest graft defects with osteoconductive or inductive materials may be of clinical benefit after bone graft harvesting, possibly reducing pain or adding structural integrity to the pelvis.
The authors report the results of a randomized control trial (RCT) using Medtronic's Mastergraft to backfill the iliac donor site versus no backfill (ie, passive hematoma evolution with time). They found no differences in donor site pain or cortical defect repair between the two groups. They did note fewer persistent medullary defects in the Mastergraft group.
While the authors speculate that fewer medullary defects might afford use of the same area for subsequent graft harvest and better fixation of instrumentation, should either be needed in the future, these outcomes were not specifically studied, and thus valid conclusions cannot be drawn. At this point, surgeons and payors may weigh whether the speculative benefits justify the costs in the absence of apparent clinical benefit.
—The Editors
The use of autogenous iliac crest has long been the gold standard in spinal arthrodesis and other orthopedic fusion procedures. Usually, ample bone is available in one posterior crest for one procedure, but frequently, patients will require multiple procedures with bone grafting, thus exhausting the supply. Additionally, the harvest of posterior crest bone will occasionally preclude the use of that ilium for fixation purposes in future spinal procedures.
There are many substances now approved as bone-void fillers by the Food and Drug Administration for use in humans. Various studies of hydroxyapatite alone [1], [2] or in a biphasic composition with beta tricalcium phosphate [3], [4] have shown good incorporation of ceramic into the host bone.
MASTERGRAFT (Medtronic Corporation, Memphis, TN, USA) is a biphasic tricalcium phosphate-hydroxyapatite ceramic approved by the Food and Drug Administration as a bone-void filler in humans. It is produced in two separate formulations: 60% hydroxyapatite and 40% beta tricalcium phosphate or 15% hydroxyapatite and 85% beta tricalcium phosphate. Biphasic ceramic compounds such as MASTERGRAFT have been shown to be safe and effective in animal [5], [6] and human studies [7] when used as a bone-void filler.
We hypothesize that the use of an osteoconductive substance to fill a defect in an iliac crest will allow for bone regeneration within that defect. Additionally, we hope to understand what impact this has on pain at the donor site.