Study Design. Retrospective cohort.
Objective. To determine the incidence of resorption after anterior lumbar interbody fusion (ALIF) and its effect on outcome.
Summary of Background Data. Recombinant human bone morphogenetic protein-2 (rhBMP-2) used in ALIF has been associated with a 0.5% to 82% incidence of resorption. This has been described as either a complication or part of the natural history. We postulate that early resorption (≤4 mo) in ALIF using femoral ring allograft augmented with rhBMP-2 supplemented with posterior instrumentation has no effect on outcome.
Methods. Institutional review board–approved retrospective 60 chart cohort study of ALIF using femoral ring allograft–augmented rhBMP-2 supplemented with posterior instrumentation from May 5, 2005, to April 6, 2010. Two groups were based upon the presence or absence of early graft resorption (≤4 mo). Patients were seen prior to surgery and postoperatively until 29 ± 20 months (last visit). Follow-up visual analogue scale pain scores and radiographical evidence of fusion were measured and compared between the 2 groups.
Results. Sixty patients, 27 females and 33 males had follow-up for 29 ± 20 months. Group 1 (33 patients, 45 levels) and group 2 (27 patients, 36 levels) were identical in age (P = 0.62), sex distribution (P = 0.43), preoperative pain score (P = 0.63), and in the rhBMP-2 dose per level (P = 0.77). There were no significant group differences in postoperative visual analogue scale scores but a trend to higher fusion rate in group 1 was seen (P = 0.07) at 6 months. There was a 40% incidence of early resorption with no significant differences in visual analogue scale scores or fusion rate between both groups.
Conclusion. There is a 40% incidence of early resorption (≤4 mo) that had no significant effect on pain score or fusion rate. Resorption should be considered part of the fusion process and not necessarily a complication.
Level of Evidence: 3