title: Correction of large (>25 cm(2)) cranial defects with "reinforced" hydroxyapatite cement: technique and complications.
abstract: BACKGROUND
  Hydroxyapatite cement is both biocompatible and osteoconductive, and it lacks significant toxic or immunogenic properties, making it an ideal substrate for the repair of cranial defects. However, with its putty-like composition, the repair of large cranial defects can be difficult because significant settling occurs as the cement hardens. We describe a technique in which we use hydroxyapatite cement, reinforced with tantalum mesh and titanium miniplates, for the repair of large (>25 cm(2)) cranial defects.
  
  
  METHODS
  After the margins of the cranioplasty are delineated, tantalum mesh is placed under the edges of the defect. Titanium miniplate single-hole bars are used to criss-cross the defect and are then secured to the surrounding bone with screws. The mesh is secured to the bars with 28-gauge stainless steel wire. Hydroxyapatite cement is applied in the defect and contoured appropriately.
  
  
  RESULTS
  We performed nine cranioplasties in eight patients ranging in age from 1.5 to 35 years (mean, 12.2 +/- 10.1 yr). The reasons for cranioplasty included cranial defect from prior trauma (n = 4), fibrous dysplasia (n = 2), infected bone flaps (n = 2), and tumor (n = 1). The cranioplasties ranged in size from 40 to 196 cm(2) (mean, 128.3 +/- 56.9 cm(2)). Follow-up ranged from 2 to 33 months (mean, 11.4 +/- 12.8 mo). Two cranioplasty constructs were removed at 1 and 3 months postoperatively owing to infection.
  
  
  CONCLUSIONS
  The use of hydroxyapatite cement with mesh and miniplates provides internal structural support and increased stability of the construct. Although this technique provides an excellent cosmetic result and no evidence to date of bony resorption, the rate of infection is alarmingly high in these large constructs.
authors.affiliation: Department of Neurosurgery, Oregon Health and Science University, Portland 97201-3098, USA.
authors.forename: Susan R
authors.initials: SR
authors.lastname: Durham
authors.forename: J Gordon
authors.initials: JG
authors.lastname: McComb
authors.forename: Michael L
authors.initials: ML
authors.lastname: Levy
mesh_terms: D000293:Adolescent; D000328:Adult; D001672:Biocompatible Materials; D001843:Bone Cements; D001860:Bone Plates; D002648:Child; D002675:Child, Preschool; D003399:Craniotomy / Q000379:methods*; D017886:Durapatite; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D016348:Osseointegration / Q000502:physiology; D011183:Postoperative Complications / Q000473:pathology / Q000601:surgery; D011474:Prosthesis Design; D019919:Prosthesis Implantation; D012086:Reoperation; D012886:Skull / Q000473:pathology; D013526:Surgical Mesh; D013635:Tantalum; D014025:Titanium
chemical_list: D001672:Biocompatible Materials; D001843:Bone Cements; D013635:Tantalum; D017886:Durapatite; D014025:Titanium