title: Incidence and outcome of graft resorption in anterior lumbar interbody fusion: using femoral ring allografts and recombinant human bone morphogenetic protein-2.
abstract: METHODS
  Retrospective cohort.
  
  
  OBJECTIVE
  To determine the incidence of resorption after anterior lumbar interbody fusion (ALIF) and its effect on outcome.
  
  
  BACKGROUND
  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.
  
  
  CONCLUSIONS
  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.
  
  
  METHODS
  3.
authors.affiliation: *Department of Orthopaedics, Cleveland Clinic, Cleveland, OH; and †Center for Spine Health, Lutheran Hospital, Cleveland, OH.
authors.forename: Mark
authors.initials: M
authors.lastname: Kayanja
authors.forename: Robert Douglas
authors.initials: RD
authors.lastname: Orr
mesh_terms: D000328:Adult; D055396:Bone Morphogenetic Protein 2 / Q000627:therapeutic use*; D001862:Bone Resorption / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D001863:Bone Screws; D016025:Bone Transplantation / Q000009:adverse effects / Q000379:methods*; D003131:Combined Modality Therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods / Q000706:statistics & numerical data; D010147:Pain Measurement; D011859:Radiography; D011994:Recombinant Proteins / Q000627:therapeutic use; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods*; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000627:therapeutic use*; D014184:Transplantation, Homologous
chemical_list: D055396:Bone Morphogenetic Protein 2; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2