The Fate of Hydroxyapatite Cement Used for Cranial Contouring: Histological Evaluation of a Case

Presentation and short-term evaluation of an all-in-one patient-specific implant for cranial reconstruction: A randomized controlled trial

Cranial reconstruction after bone graft harvesting remains a challenge. A patient-specific implant (PSI) to guide harvesting and reconstruction was evaluated and compared with the use of a free-hand procedure with calcium phosphate cement (C). Patients were randomized to either the PSI or C group. The outcome was measured clinically and radiographically as the primary endpoint. Secondary endpoints were ease of application, patient and surgeon satisfaction, and the complication rate. Twenty patients were randomized to the PSI (n=10) and C (n=10) groups. Two PSI patients were switched to the cement group due to a poor fit of the PSI. There was a non-significant trend towards more successful outcomes in the PSI group. Two PSI patients presented palpable screws, and one cement patient had a palpable dimple. Cone beam computed tomography showed a significantly lower median volume discrepancy in the PSI group (P<0.0001). The total surgical manipulation time was significantly higher in the PSI group. At 10 days postoperative, three PSI and two C patients presented with minor postoperative complications. There was no significant difference in patient or surgeon satisfaction. PSIs are a reliable alternative to cement. This PSI is novel as it also serves as a guide for harvesting the bone blocks required for reconstructive purposes.

Frontal bone remodeling for gender reassignment of the male forehead: a gender-reassignment surgery

Gender-reassignment therapy, especially for reshaping of the forehead, can be an effective treatment to improve self-esteem. Contouring of the cranial vault, especially of the forehead, still is a rarely performed surgical procedure for gender reassignment. In addition to surgical bone remodeling, several materials have been used for remodeling and refinement of the frontal bone. But due to shortcomings of autogenous bone material and the disadvantages of polyethylene or methylmethacrylate, hydroxyapatite cement (HAC) composed of tetracalcium phosphate and dicalcium phosphate seems to be an alternative. This study aimed to analyze the clinical outcome after frontal bone remodeling with HAC for gender male-to-female reassignment. The 21 patients in the study were treated for gender reassignment of the male frontal bone using HAC. The average age of these patients was 33.4 years (range, 21–42 years). The average volume of HAC used per patient was 3.83 g. The authors’ clinical series demonstrated a satisfactory result. The surgery was easy to perform, and HAC was easy to apply and shape to suit individual needs. Overall satisfaction was very high. Therefore, HAC is a welcome alternative to the traditional use of autogenous bone graft for correction of cranial vault irregularities.

Craniofacial reconstruction with bone and biomaterials: review over the last 11 years

This review aims to compare bone grafts and different biomaterials for reconstruction of craniofacial bones in congenital defects, after trauma, and after tumour surgery. A Pubmed search was performed and publications over the last 11 years describing reconstructions of craniofacial bones in non-load-bearing areas were reviewed. Only human studies using bone grafts and biomaterials were included. Studies on skull base reconstruction, distraction osteogenesis, free and pedicled bone flaps and bone-anchored epithesis were excluded. Out of 83 studies, three were prospective, 65 retrospective and 15 studies were case reports. There were seven comparative studies found and some efforts on statistical analysis were made. Except for a few studies, the statistical significant differences in outcomes were found to be related to size and location of bone defects rather than reconstruction method and biomaterial used. An increasing number of alloplastic materials have been available as alternatives to the gold standard autologous bone transplantation for craniofacial bone repair. Comparative studies with statistical analyses on differences in success rates between different biomaterials or bone grafts for specific indications are needed.

Bone graft materials

This article examines each class of bone grafting material based on some of the studies in each of the following categories: safety, animal research, periodontal and maxillofacial applications, skeletal grafting, and attempts to qualify the efficacy of each class of material. The article also examines some of the research being done in "tissue engineering" to get a sense of the future of bone grafting.

Use of Calcium-Based Bone Cements in the Repair of Large, Full-Thickness Cranial Defects: A Caution

BACKGROUND

Calcium-based bone cements have increased in popularity for the correction of craniofacial contour defects. The authors' experience with them in more than 120 patients has resulted in the establishment of strict criteria for their use. Although the authors' overall complication rate with these cements has been low, certain patient groups have an unacceptably high complication rate. The authors describe their experience with the repair of large, full-thickness cranial defects using calcium-based bone cements.

METHODS

The study group comprised 16 patients who underwent correction of large, full-thickness (>25 cm2) skull defects. The surgical technique included reconstruction of the floor of the defect with rigid fixation to the surrounding native bone, interposition of the cement to ideal contour, and closure of the defect.

RESULTS

The mean patient age was 35 years (range, 1 to 69 years). The mean defect area was 66.4 cm2 (range, 30 to 150 cm2). Cases were equally divided between BoneSource and Norian CRS. The mean amount of bone cement used was 80 g. Follow-up varied between 1 and 6 years (mean, 3 years). Major complications occurred in eight of 16 patients, with one occurring as late as 6 years postoperatively. Complications occurred throughout the course of review, indicating that they were not caused by a learning curve.

CONCLUSION

Because of the unacceptably high complication rate with the use of calcium-based bone cements in large skull defects, the authors believe that their use is contraindicated and have returned to using autogenous split skull cranial bone reconstruction for these patients.

Contouring of Cranial Vault Irregularities With Hydroxyapatite Cement: A Clinical and Experimental Investigation

The biocompatible hydroxyapatite cement (HAC) is a welcome alternative to the traditional use of autogenous bone for postoperative corrections of cranial vault irregularities. The authors performed experimental studies to show the safety and osseointegration capacity of HAC on animal models and confirm the osseous replacement without toxic reactions. The purpose of the current study was to analyze the clinical outcome after correction of secondary cranial vault irregularities with HAC. Twenty-one patients were treated for residual cranial frontal bone defects after craniotomy with HAC (Bone Source, Stryker Leibinger GmbH, D-79111 Freiburg, Germany). The average age was 38.5 years (range, 23-57 years). All of the patients were male. The average volume per patient was 53.83 g. The volume implanted ranged from 25 to 125 g; in all cases the dura was covered with bone. Irregularities resulted from sunken bone. The authors' clinical series demonstrates that a satisfactory and aesthetically pleasing result can be achieved in one surgical intervention in patients for surgical correction of postoperative cranial vault irregularities using HAC. It permits osseointegration, which makes it relatively resistant to infection. HAC is easy to apply and shape to suit individual needs. HAC is a welcome alternative to the traditional use of autogenous bone for postoperative corrections of cranial vault irregularities.