BONE-GRAFT HARVEST SITE AS A DETERMINANT OF ILIAC CREST STRENGTH

Bone graft harvest site fracture can occur after removal of bone from the anterior iliac crest. No biomechanically proven guidelines for saf e removal of bone exist. Cadaveric hemipelves were tested in a materia ls testing system machine, with the harvest site occurring 15-mm poste rior to the anterosuperior iliac spine in 8 specimens and 30-mm poster ior in 7 specimens. These pelves were then tested to failure by simula ting avulsion fractures caused by the forces of the flexors of the hip . Average force at failure was 783 N (standard deviation, +/-333 N) in the 15-mm group and 1917 N (standard deviation, +/-735) in the 30-mm group. This study provides objective data which demonstrate that harve st 30 mm posterior to the anterosuperior iliac spine weakens the iliac crest less than harvest 15 mm posterior to the anterosuperior iliac c rest. To minimize the possibility of iliac crest fracture after bone g raft harvest, bone should be removed at least 30 mm from the anterior superior iliac spine.