Concern about iliac crest bone graft (ICBG) harvest site morbidity has helped create a massive bone graft substitute industry and prompted many spine surgeons to use local bone graft and bone graft substitutes instead of ICBG, despite ICBG resulting in better fusion rates. The major concern relates to ICBG harvest site pain, though increased blood loss, operating time, hematoma formation, infection, and the potential for injury to surrounding structures are other reasons cited to avoid ICBG. While ICBG harvest site morbidity has traditionally been accepted as fact, more recent research suggests that long-term pain or other major complications are in fact quite rare when harvest is performed through the same midline incision used for lumbar fusion. In order to better assess ICBG harvest site pain, Lehr and colleagues from The Netherlands performed a prospective, patient-blinded study in which ICBG was randomly harvested from either the right or left iliac crest and patients were asked to identify from which side the graft was taken and to rate their midline back pain and bilateral iliac crest pain at baseline and then at four follow-up visits out to one year. This study was performed as part of a larger investigation comparing calcium bone graft substitute to ICBG. Ninety-two patients underwent instrumented lumbar fusion for degenerative conditions, with the fusion extending to the lower lumbar spine (L3 or more caudal). The majority (87%) underwent one or two level fusion. All patients had ICBG harvested and placed in one lateral gutter, with the calcium bone graft substitute placed on the contralateral side. The ICBG was harvested by creating a unicortical iliac crest window and removing the cancellous bone with gauges. Median harvested bone graft volume was 6 cc. Following surgery, 49% of patients reported that they did not know from which side the ICBG was harvested or answered inconsistently across the four follow-up visits. Of the 51% who felt they could identify which crest was harvested and answered consistently at all follow-up visits, 48% identified the correct harvest site and 52% identified the wrong crest. Overall, 24% of patients consistently and correctly identified the ICBG site over the first year following surgery. There were no significant differences in median iliac crest pain scores between the harvested and intact iliac crests at any follow-up point, and iliac crest pain scores correlated with midline low back pain scores. Based on this, the authors concluded that ICBG harvest did not result in increased pain at the harvest site, and that concern about harvest site pain should not be the main reason to avoid ICBG harvest.
The authors have done an elegant study and compelling analysis, which strongly suggests that most patients do not experience prolonged ICBG harvest site pain. The study design was appropriate, though it does have a few significant limitations. The amount of bone graft harvested seems very low (median of 6 cc), and most surgeons traditionally harvest more than this. A more extensive bone graft harvest could result in higher levels of graft site pain. The authors did not report any complications related to bone graft harvest or discuss any increase in blood loss associated with the procedure. While rare, complications related to graft site harvest do occur (i.e. hematoma, infection, injury to structures in the sciatic notch), and any additional surgical work increases blood loss. They also note that median bone graft harvest only took 7.5 minutes, which might be related to the low volume of graft obtained. A more thorough harvesting technique, irrigation, control of bleeding bone, and closure typically takes longer than that. Despite these limitations, the current study and recent literature suggests that pain and morbidity associated with ICBG harvest is much lower than suggested by the historical literature on the topic. The earlier studies frequently included harvest through a separate incision and removal of the entire outer cortex of iliac crest. At this point, surgeons may be avoiding ICBG harvest more out of an effort to reduce time in the operating room than out of concern for harvest site morbidity. However, this study and others suggest that ICBG should be strongly considered as a graft option given its better osteoinductive properties and low morbidity associated with its harvest.
Please read the article on this topic in the April 15 issue. Does this change your view about the morbidity of ICBG harvest? Let us know by leaving a comment on The Spine Blog.
Adam Pearson MD, MS
Associate Web Editor