Understanding Bony Safety Zones in the Posterior Iliac Crest

Abstract

Morphometric analysis of the human ilia obtained from the Hamann-Todd Collection at Cleveland Museum of Natural History. To identify whether gender and pelvis size affect the distances between anatomic landmarks of the posterior pelvis. The iliac crest bone harvest is commonly performed in orthopedic, neurosurgic, and maxillofacial surgery. Morbidity from the bone graft harvest is well described (Arrington et al, Clin Orthop Relat Res 1996:300-9; Ebraheim et al, J Am Acad Orthop Surg 2001;9:210-8; Hu and Bohlman, Clin Orthop Relat Res 1994;208-13; Kahn, Clin Orthop Relat Res 1979;204-7; Kurz et al, Spine 1989;14:1324-31; Lim et al, Spine 1996;21:2376-8; Sasso et al, J Bone Joint Surg Am 1998;80:631-5; St. John et al, A J Orthop (Belle Mead NJ) 2003;32:18-23; Summers and Eisenstein, J Bone Joint Surg Br 1989;71:677-80). Several studies have advanced our understanding of the bony, vascular, and neurologic anatomy of the posterior iliac crest (Ebraheim et al, J Am Acad Orthop Surg 2001;9:210-8; Xu et al, Spine 1996;21:1017-20). There is no literature documenting the measurement of this region on a large, statistically significant scale. An anatomic study was undertaken using the Hamann-Todd collection. The bilateral human ilia were examined from 50 men and 50 women between 18 and 80 years of age. Age, gender, and side were recorded. Four parameters were recorded: the shortest distance from the posterior superior iliac spine to the sciatic notch (PN), the shortest distance from posterior superior iliac spine to the sacroiliac joint (PS), the anterior-posterior length of the sciatic notch (P90), and the maximum length of the sacroiliac joint (SI). The right and left ilia were compared, and no significant difference was found. The mean for all 4 measurements was slightly larger in men and statistically significant (PN: men 43.7 +/- 4.6 mm vs. women 39.7 +/- 5.8 mm; PS: 21.5 +/- 7.8 mm vs. 16.9 +/- 5.3 mm; P90: 16.7 +/- 3.8 mm vs. 15.3 +/- 3.6 mm; SI: 60.0 +/- 5.9 mm vs. 55.2 +/- 5.8 mm). The ranges and distribution of data within the ranges were compared. Men had higher maximum limits although the lower limits were similar (PN: men 28.7-62.7 mm vs. women 28.0-51.0 mm; PS: 7.3-43.3 mm vs. 4.7-34.3 mm; P90: 9-25.3 mm vs. 7.7-22.7 mm; SI: 42.3-69 mm vs. 50.0-79.0 mm). This study defines distances in the posterior iliac crest beyond which the risk of injuring important structures is present (2.80 cm for 100% of the population or 3.00 cm for > or = 90%).