Analysis of Iliac Crest Bone Graft Process Measures

PURPOSE: The use of autogenous iliac crest bone graft (ICBG) is considered the gold standard for performing spinal fusions. We conducted a prospective observational study of posterior ICBG harvesting using process measures to establish a normative bone harvesting database for future comparative studies and analysis of bone graft substitutes.

METHODS: Between August 2000 and February 2002, autogenous posterior ICBG was obtained from 36 consecutive patients (29M, 7F) using a separate incision and the “trephine curettage” technique. The average age was 40 years (28-62) while the index procedure included TLIF (25), PSF (4), ASF-PSF (5), PLIF (2). Data collection included estimated blood loss (EBL) for the procedure and the harvest proper, total time for harvest, and total bone harvested. Sacroiliac joint violation was assessed from CT images in which the ICBG site was clearly visualized.

RESULTS: For the index procedure the EBL averaged 681 cc (range 150-1500), and for the ICBG harvest the EBL averaged 66 cc (range 20-200). Average harvest time was 37 minutes (range 20-51) with an average bone harvest volume of 37 cc (range 25-65). The ICBG site/sacroiliac joint was clearly visualized in 26 of 36 patients (72%) with 3 sacroiliac joint violations (12%) . These included the synovial portion of the joint in two cases.

CONCLUSIONS: With emergence of bone graft substitutes, the costs and benefits of autogenous ICBG harvesting will be scrutinized. This database establishes a benchmark for additional EBL, operative time, volume of harvest, and SI joint violation for ICBG harvest. This is the first report of routine post-op CT evaluation for SI joint violation, which may be more common than previously reported.