title: Enhancing dermal and bone regeneration in calvarial defect surgery.
abstract: BACKGROUND
  To optimize the functional and esthetic result of cranioplasty, it is necessary to choose appropriate materials and take steps to preserve and support tissue vitality. As far as materials are concerned, custom-made porous hydroxyapatite implants are biomimetic, and therefore, provide good biological interaction and biointegration. However, before it is fully integrated, this material has relatively low mechanical resistance. Therefore, to reduce the risk of postoperative implant fracture, it would be desirable to accelerate regeneration of the tissues around and within the graft.
  
  
  OBJECTIVE
  The objective was to determine whether integrating growth-factor-rich platelet gel or supportive dermal matrix into hydroxyapatite implant cranioplasty can accelerate bone remodeling and promote soft tissue regeneration, respectively.
  
  
  METHODS
  The investigation was performed on cranioplasty patients fitted with hydroxyapatite cranial implants between 2004 and 2010. In 7 patients, platelet gel was applied to the bone/prosthesis interface during surgery, and in a further 5 patients, characterized by thin, hypotrophic skin coverage of the cranial lacuna, a sheet of dermal matrix was applied between the prosthesis and the overlying soft tissue. In several of the former groups, platelet gel mixed with hydroxyapatite granules was used to fill small gaps between the skull and the implant. To confirm osteointegration, cranial computed tomography (CT) scans were taken at 3-6 month intervals for 1-year, and magnetic resonance imaging (MRI) was used to confirm dermal integrity.
  
  
  RESULTS
  Clinical examination performed a few weeks after surgery revealed good dermal regeneration, with thicker, healthier skin, apparently with a better blood supply, which was confirmed by MRI at 3-6 months. Furthermore, at 3-6 months, CT showed good biomimetism of the porous hydroxyapatite scaffold. Locations at which platelet gel and hydroxyapatite granules were used to fill gaps between the implant and skull appeared to show more rapid integration of the implant than untreated areas. Results were stable at 1-year and remain so to date in cases where follow-up is still ongoing.
  
  
  CONCLUSIONS
  Bone remodeling time could be reduced by platelet gel application during cranioplasty with porous hydroxyapatite implants. Likewise, layering dermal matrix over such implants appears to promote dermal tissue regeneration and the oshtemo mimetic process. Both of these strategies may, therefore, reduce the likelihood of postsurgical fracture by promoting mechanical resistance.
authors.affiliation: Neurosurgery Clinic, University of Udine, Reggio Emilia, Italy.
authors.forename: Bruno
authors.initials: B
authors.lastname: Zanotti
authors.affiliation: Department of Plastic and Reconstructive Surgery, University of Udine, Reggio Emilia, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Zingaretti
authors.affiliation: Department of Plastic and Reconstructive Surgery, University of Udine, Reggio Emilia, Italy.
authors.forename: Daria
authors.initials: D
authors.lastname: Almesberger
authors.affiliation: Neurology Unit, Free University of Neuroscience "Anemos", Reggio Emilia, Italy.
authors.forename: Angela
authors.initials: A
authors.lastname: Verlicchi
authors.affiliation: Neurosurgery Clinic, A.O. Spedali Civili, Brescia, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Stefini
authors.affiliation: Urologic Clinic, Catholic University Medical School of Rome, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Ragonese
authors.affiliation: Department of Plastic and Reconstructive Surgery, University of Udine, Reggio Emilia, Italy.
authors.forename: Gianni Franco
authors.initials: GF
authors.lastname: Guarneri
authors.affiliation: Department of Plastic and Reconstructive Surgery, University of Udine, Reggio Emilia, Italy.
authors.forename: Pier Camillo
authors.initials: PC
authors.lastname: Parodi
keywords: Biomaterials integration; bone regeneration; cranioplasty; dermal matrix; platelet gel