title: Sandwich allografts for long-bone nonunions in patients with osteogenesis imperfecta: a retrospective study.
abstract: BACKGROUND
  Patients with osteogenesis imperfecta often develop nonunions, as internal fixation has limited applicability in this condition. We report the outcomes of a modified "sandwich technique" in the treatment of long-bone nonunions in patients with osteogenesis imperfecta; this technique brings circumferential stabilization and normal collagen to the nonunion site.
  
  
  METHODS
  From May 2003 through February 2012, twelve patients (eight females, four males; median age, 39.0 years; range, eleven to seventy-eight years) who had osteogenesis imperfecta (Sillence type I [three], type III [eight], and type IV [one]) and a combined total of thirteen nonunions (two humeral, two radial, three femoral, four tibial, and two ulnar; median duration, 15.0 months; range, six to 204 months) were treated at our institution with compressed sandwich allograft cortical struts. The struts were fashioned to be wide enough to allow for increased osteoconductive surface area and to approximate a hemicylindrical shape. Treatment history and demographics data were acquired through retrospective chart review. Follow-up radiographs were analyzed by two attending orthopaedic surgeons to determine radiographic findings. The median follow-up time was 4.6 years (range, 2.1 to 10.3 years).
  
  
  RESULTS
  All thirteen nonunions, including one requiring a second graft procedure, healed with abundant, smooth allograft incorporation, resulting in an initial healing rate of 92% because of a refracture in one patient. This patient's nonunion ultimately healed with additional allograft struts and a new intramedullary rod. One patient required removal of prominent screws. The final follow-up examinations revealed no pain or refracture at the original nonunion site. All patients regained their prefracture level of function.
  
  
  CONCLUSIONS
  Sandwich allograft struts constitute a durable, safe method for the stabilization and healing of persistent long-bone nonunions in patients with osteogenesis imperfecta. All patients showed incorporation of the allograft to the native diaphysis.
authors.affiliation: c/o Rachel Box, ELS, Senior Editor and Director, Editorial Services, Department of Orthopaedic Surgery, The Johns Hopkins University, Johns Hopkins Bayview Medical Center, 4940 Eastern Avenue, #A665, Baltimore, MD 21224-2780. E-mail address: rbox1@jhmi.edu.
authors.forename: Varun
authors.initials: V
authors.lastname: Puvanesarajah
authors.affiliation: c/o Rachel Box, ELS, Senior Editor and Director, Editorial Services, Department of Orthopaedic Surgery, The Johns Hopkins University, Johns Hopkins Bayview Medical Center, 4940 Eastern Avenue, #A665, Baltimore, MD 21224-2780. E-mail address: rbox1@jhmi.edu.
authors.forename: Jay R
authors.initials: JR
authors.lastname: Shapiro
authors.affiliation: c/o Rachel Box, ELS, Senior Editor and Director, Editorial Services, Department of Orthopaedic Surgery, The Johns Hopkins University, Johns Hopkins Bayview Medical Center, 4940 Eastern Avenue, #A665, Baltimore, MD 21224-2780. E-mail address: rbox1@jhmi.edu.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Sponseller
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D064591:Allografts / Q000637:transplantation*; D055396:Bone Morphogenetic Protein 2 / Q000627:therapeutic use; D016025:Bone Transplantation / Q000379:methods*; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D005599:Fractures, Ununited / Q000000981:diagnostic imaging / Q000209:etiology* / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010013:Osteogenesis Imperfecta / Q000150:complications* / Q000000981:diagnostic imaging / Q000601:surgery*; D011182:Postoperative Care / Q000379:methods; D011859:Radiography; D011994:Recombinant Proteins / Q000627:therapeutic use; D012189:Retrospective Studies; D014184:Transplantation, Homologous; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D011994:Recombinant Proteins