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  • Clinical Outcome and Bone Regenerative Effects from Using Calcium Phosphate-based Implants in Cranial Repair

    Final Number:

    Thomas Engstrand MD, PhD; Lars Kihlstrom; Margarita Trobos PhD; Omar Omar pHD; Håkan Engqvist PhD; Peter Thomsen PhD

    Study Design:
    Clinical Trial

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2016 Annual Meeting

    Introduction: Autologous bone and alloplastic materials used for cranial repair are associated with resorption, infection and extrusion. Materials with regenerative features may improve outcome. A bone regenerative calcium-phosphate based implant was used in the present retrospective study. The primary objective was to determine complication rate, as defined as number of explantations due to infection and/or extrusion. The secondary objective was to uncover evidence of bone formation induced by the implant.

    Methods: 150 patients with cranial defects were treated. The follow-up time was 1-60 months (mean 23 months). In two patients, biopsies were taken 9 and 50 months after surgery, respectively, for gene expression analyses and histological examinations.

    Results: The explantation rate was 5,3 % in the cohort where approximately 40 % of treated patients had a history of previously failed autologous bone flaps or conventional implants. Early postoperative wound dehiscence and infection occurred in 8 cases. Five patients had local revision due to wound dehiscence that healed without implant removal. A majority of failures occurred within 3 months after surgery. Two patients had late onset titanium exposure adjacent to the ceramic implants that necessitated partial revision. Gene expression analyses 9 months postoperatively revealed expression of osteocalcin, type I collagen, osteopontin, calcitonin receptor, and cathepsin K within the reconstructed area, and up-regulation of type I collagen expression in the soft tissue covering the implant. Histological examination 50 months postoperatively revealed vascularized compact bone within the reconstructed area.

    Conclusions: Weak quality of soft tissue covering the implant, caused by irradiation or scars, and smoking are identified as major risk factors. We believe that the process of new bone formation as well as new collagen deposition in neighboring soft tissue induced in situ by the ceramic implant may contribute to a reduction of the number of postoperative complications.

    Patient Care: Increased awareness of the complication rates of cranioplasty and the available options may lead to decreased rates of post-operative complications and less need for revision surgery.

    Learning Objectives: By the conclusion of this session, participants should be able to: 1) Discuss material options for cranial repair from a risk/benefit perspective 2) Understand the time factor involved with cranioplasty complications 3) Differentiate between bioactive and non-bioactive implants for cranial repair


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