Cranioplasty Material Research Articles

Post-operative complications with titanium mesh

Titanium mesh is a commonly used material for cranioplasty. While it is a safe and highly biocompatable material, it can modify the presentation of post-operative complications. This case report details 3 patients (2 recurrent meningiomas and an extradural haematoma) in whom post-operative complications, although not caused by the titanium mesh, were modified in their presentation by the permeability of the material. The permeable nature of the mesh allows intracranial pathological processes to extend extracranially and vice versa.

Broken bioceramic used in a computer-assisted reconstruction of the frontal skull bone

We report a complication occurring after the use of a bioceramic material for a three-dimensional reconstructive cranioplasty. A patient who had a satisfactory aesthetic result after frontal skull bone reconstruction with bioceramic injured his head after falling out of bed. The bioceramic material fragmented and the three fragments migrated over each other to form a lump. The bioceramic material had to be surgically removed. Care must be taken when using the fragile bioceramic material for reconstructive purposes, especially when patients are at risk of frequent falls.

Long-Term Follow-Up Experience with Carbonated Calcium Phosphate Cement (Norian) for Cranioplasty in Children and Adults

Despite the growing popularity of calcium-based bone cements as a cranioplasty material, the long-term success and complication rates of these materials remain largely controversial. The authors reviewed their extended experience with Norian, a carbonated calcium phosphate bone cement, for cranioplasty. A retrospective chart review of all patients who underwent cranioplasty using Norian over the past 9 years was conducted. Patients with less than 1 year of follow-up were excluded. Forty-six patients were studied. Follow-up averaged 43.9 months (range, 12.1 to 109.8 months). The overall complication rate was 26 percent, and included infection (n = 9), seroma (n = 1), or a chronically draining sinus (n = 2). Average time to onset of a complication was 20.2 months (range, 2.3 to 89.2 months). Two of nine infections resolved with oral antibiotics; the remaining complications required surgical intervention for definitive treatment. Factors associated with a statistically increased risk of complications were amounts of Norian used (p < 0.01) and onlay application with a high probability for bacterial contamination (p = 0.001), whereas reconstruction of full-thickness cranial defects larger than 25 cm trended toward worse outcomes (p > 0.05). Norian is well suited for cranioplasty when used in moderate amounts for onlay applications, as evidenced by acceptable complication rates and contouring ability in this setting. Its use in large amounts as an onlay, inlay full-thickness cranial reconstruction of large defects or areas with potential bacterial contamination should be avoided. Complications or construct failure may occur months or even years after implantation, even under ideal circumstances.

Surgical management and outcome of large orbitocranial osteomas

The goal of this study is to review the surgical management and outcome of patients who were treated for large orbitocranial osteomas at Gulhane Military Medical Academy over a period of 7 years. Twenty-one patients with large orbitocranial osteomas were evaluated retrospectively. All patients were male and between 19 and 25 years old. Surgery was performed in all patients. The main surgical procedure was resection of the osteoma using orbitotomy and/or craniotomy followed by orbital reconstruction and cranioplasty. Cranioplasty was performed in 16 patients, using methyl methacrylate in 5 patients (31%) and porous polyethylene in 11 patients (69%). Thin, flexible, porous polyethylene was preferred for orbital reconstruction in 10 patients. The cranioplasty materials were attached to the intact bone using miniplates. There were no severe postoperative complications. Mild transient periorbital ecchymosis was noted in 19 patients. The mean follow-up period was 11.7 months (range 9-24 months) after surgery. No tumor regrowth was observed in any patient at the end of the follow-up period. Large osteomas of the orbitocranial region must be resected for cosmetic and functional reasons. Selection and planning of the surgical technique should be based on the direction of the tumor growth and on the size of the tumor and the structures that are compressed by the tumor.

P.093 A new cranial bone reconstruction technique by biomaterials

Current alloplastic materials such as PMMA, titanium or PEEK don't show relevant bone ingrowth into the implant when used for cranioplasty, ceramic implants have the drawback being brittle. New materials and implant designs are urgently needed being biocompatible, stable enough for cranioplasty and stimulating bone formation. In an in vivo critical size sheep model circular cranial defects (>2.4 cm) were covered with three different types of a 3D-printed porous titanium scaffolds with multidirectional, stochastically distributed architecture (uncoated scaffold, hydroxyapatite-coated scaffold, uncoated scaffold filled with a calcium phosphate bone cement paste containing β-TCP granules). An empty titanium mesh served as control. Among the different investigated setups the hydroxyapatite-coated scaffolds showed a surprisingly favourable performance. Push-out tests revealed a 2.9 fold higher force needed in the hydroxyapatite-coated scaffolds compared to the mesh group. Mean CT density at five different points inside the scaffold was 2385HU in the hydroxyapatite-coated group compared to 1978HU in the uncoated scaffold at nine months. Average lateral bone ingrowth after four months in the hydroxyapatite-coated scaffold group was up to the implant center, 12.1 mm on average, compared to 2.8 mm in the control group covered with mesh only. These properties make the investigated scaffold with multidirectional, stochastically distributed structure superior to all products currently on the market. The study gives a good idea of what future materials for cranioplasty might look like.

Factors affecting graft infection after cranioplasty

The aim of this study was to identify the risk factors associated with bone grafts infection after cranioplasty. Eighty-four cranioplasties were performed on 75 patients between 2002 and 2006. Cryopreserved bone grafts were used as graft material in group 1 and polymethylmethacrylate (PMMA) was used in group 2. Risk factors including age, gender, time intervals between craniectomy and cranioplasty, mechanism of injury, number of procedures, graft material, and the Glasgow Coma Scale score were compared between groups. Swab culture results and bone graft infection were assessed in group 1. Multiple procedures before cranioplasty and an inadequate time interval between craniectomy and cranioplasty increase the risk of infection after cranioplasty. Swab culture results, age, gender, mechanism of injury, graft material and Glasgow Coma Scale score are not related to infection. The use of PMMA was associated with a relatively low risk of infection (6.25%). Risk of graft infection was not associated with the choice of graft material in the present study. Multiple procedures and insufficient time intervals increase the risk of infection. Interrupting the wound healing process may be the cause of infection. PMMA is a safe material for cranioplasty regardless of previous infection.

Use of Cortoss™ as an Alternative Material in Calvarial Defects

A clinical series of 13 patients who underwent cranioplasty using a new quick setting material, namely Cortoss, was done over 3-year period. Thus, the primary objective of this study is to evaluate the role of Cortoss in the treatment calvarial defects which were mainly due to trauma (4 patients), tumor or tumor-like lesions (5 patients), middle cerebral infarction (3 patients), and gun shot wound (1 patient). The surgical technique was found to be simple and effective. Long-term follow-up (mean 24.3 months) demonstrated satisfactory results in terms of surgical (functional) and cosmetic outcomes. None of the patients developed complications including infections, foreign body reactions or material leakage. The results led us to suggest that the use of Cortoss in the case of calvarial defects seems to be safe, effective, quick, and a feasible method for cranioplasty. We conclude that the mechanical, immunologic, and technical-grafting properties of Cortoss, together with its superior esthetic and psychological effects, probably will make it the best material for cranioplasty.

A 12 month in vivo study on the response of bone to a hydroxyapatite–polymethylmethacrylate cranioplasty composite

We investigated the osteoconductivity and biocompatibility in vivo of a new hydroxyapatite–polymethylmethacrylate (HA–PMMA) composite developed for use as an implant material for cranioplasty, which is expected to have the good osteoconductivity of HA together with the strength and ease of handling of PMMA. The HA–PMMA composites were implanted in eight full-grown beagles and then 6, 12, 24 weeks and 1 year after implantation, the animals were sacrificed and the implanted materials removed along with the surrounding tissues. Extirpated specimens were studied using an optical microscope and micro-computed tomography (micro-CT). Fibrous connective tissue was prominent in the interface of the composite at 6 weeks. New bone formation was seen around the implant, 12 and 24 weeks after operation. At 1 year, new bone filled in the interface of the HA–PMMA composite and adhered to the surrounding autogenous bone. Mixing HA and PMMA did not interfere with the osteoconductivity of the HA component. In micro-CT findings, the new bone growing on the HA–PMMA composite could be seen attaching preferentially to HA particles exposed at the composite surface, rather than the PMMA. This study demonstrated that this HA–PMMA composite is a good candidate for cranial bone implants due to its good osteoconductivity and biocompatibility.

Clinical evaluation of the polypropylene-polyester knit used as a cranioplasty material

The paper presents clinical evaluation of the polypropylene-polyester knit used as a cranioplasty material. Between year 1980 and 2002 275 cranioplastic procedures using the polypropylene-polyester plates Codubix were carried out in the Department of Neurosurgery of the Medical University of Łódź. There were 146 patients who primarily sustained head injuries and 129 non-traumatic patients with craniectomies carried out for various other reasons. In the majority of cases, i.e. in 158 patients, cranioplasty was performed later than 6 months after the primary surgery. The largest implant measured 430 cm2. Excellent and good outcome was achieved in 92% of the patients whereas the rate of local infection was 8%. Codubix knitted polypropylene-polyester implant proved to be useful and a safe cranioplastic material.

Antibiotic Elution from Hydroxyapatite Cement Cranioplasty Materials

Hydroxyapatite cements (HAC) are a contemporary material used for multiple cranioplasty applications. In an effort to decrease the risk of postoperative infection, mixing antibiotics into the material during intraoperative application is frequently done. It has been assumed, but never substantiated, that significant antibiotic release from the material occurs after implantation. Using standardized morphologies, a mixture of a specific HAC (Mimix bone void filler) and tobramycin antibiotic was prepared, hydrated in phosphate-buffered saline, and tested in vitro for as long as 22 days after preparation. The results show that the majority of the antibiotic (91%) was released within the first 24 hours, with the balance being eluted during the next 8 days. Overall, the release of tobramycin from Mimix bone void filler appears to fit the pattern of antibiotic release demonstrated to occur from other bioabsorbable ceramic-type carriers.

Measuring Pulsatile Forces on the Human Cranium

The cyclic stresses in the cranium caused by pulsation of the brain play an important role in the design of materials for cranioplasty, as well as craniofacial development. However, these stresses have never been quantified. In this study, the force in the epidural space against the cranium was measured intraoperatively in 10 patients using a miniature force probe. Heart and ventilatory rates computed from the force tracing correlated closely with the corresponding measured values in the patients, confirming that the forces measured were indeed a result of brain pulsation. The mean outward systolic normal and tangential stresses were 54.2 kilo-Pascals (kPa) and 345.4 kPa, respectively. The systolic shear stress was 199.8 kPa. Through mechanotransduction, these stresses play a role in cranial development. The calculated yield stress of a cranioplasty repair was 0.4 MPa, which is within one order of magnitude of the known strength of common calcium-phosphate cements. This indicates a possible relation of these pulsatile forces and occult failure of calcium-phosphate cement cranioplasties through material fatigue.

Biomechanical Testing of Alloplastic PMMA Cranioplasty Materials

Alloplastic cranioplasty techniques using polyfmethylmethacrylate (PMMA) are a common method of restoring lost cranial bone. Numerous compositions of PMMA exist for this application, using either intraoperatively cured solid compositions or preoperatively fabricated porous custom implants. Although all of these PMMA materials feel solid by palpation, the amount of cranial protection that they provide has never been precisely evaluated. Whether differences exist between the differing PMMA cranioplasty materials likewise is unknown. An impact resistance test was performed on uniform-size blocks of differing PMMA materials of representative cranial thickness using American Society of Testing and Materials (ASTM) method D 3029-78. Based on mean failure weights of 3.9 lb (Cranioplast), 4.2 lb (Cranioplexx), and 4.0 lb (HTR polymer), all of these materials are comparatively the same in impact resistance. Precured porous PMMA, despite having 30% to 40% less material, offered no less impact resistance. Based on projections to cranial bone, PMMA materials appear to offer protection similar to that of native osseous tissue.

Bone autografting of the calvaria and craniofacial skeleton: historical background, surgical results in a series of 15 patients, and review of the literature

Background Although the use of autologous bone for reconstruction of the cranial and facial skeleton underwent a partial reappraisal following the introduction of a vast range of alloplastic materials for this purpose, it has demonstrated definite advantages over the last century and, particularly, during the last decade. Methods Fifteen patients underwent cranial and/or cranio-facial reconstruction using autologous bone grafting in the Department of Neurologic Sciences-Neurosurgery and the Division of Maxillo-Facial Surgery of the Rome “La Sapienza” University between 1987 and 1995. This group of patients consisted of 8 females and 7 males whose average age was 29.5 years (range 7.5 to 59 years, mean age 30). In all these patients cranioplasty and/or cranio-facial reconstruction had been performed to repair bone defects secondary to benign tumors or tumor-like lesions (12 cases), trauma (2 cases), or, in the remaining case, to wound infection after craniotomy for a neurosurgical operation. Results The results obtained in a series of 15 patients treated using this method are described with reference to the abundant data published on this topic. Conclusion The mechanical, immunologic, and technical-grafting properties of autologous bone, together with its superior esthetic and psychological effects, probably make it the best material for cranioplasty.

Major Complication in Methyl Methacrylate Cranioplasty-A Case Report

The main purposes of reconstruction of cranium are the protection of the brain from injury and to restore better aesthetic contour. Methyl methacrylate is the most commonly used alloplastic material in cranioplasty. Especially in large cranial defect, it offers the craniofacial surgeons an alternative in cranioplasty when autogenous bone graft is not indicated or not sought by the patient. However its complications such as infection, loosening and extrusion do occur. We present a case of frontal cranioplasty using methyl methacrylate cement with major complication. The complication developed 5 months after methyl methacrylate cranioplasty; forehead overlying skin necrosis and exposure of methyl methacrylate cement was noted. We managed the case with removal the cement, reconstruction of frontal bone with autogenous split-thickness calvarial bone graft, and free radial forearm flap coverage. The aesthetic result was poor. Scarring skin and soft tissue replacement before cranioplasty either with tissue expander or free skin flap transfer may prevent the patient from this major complication.

Biomechanical properties of calvarium prosthesis

There are many materials available for the reconstruction of calvarial defects. Even though their biomaterial properties are well known, the biomechanical properties as part of the calvarium have not been investigated. In this article, calvarial implants are reviewed with their historic development into modern cranioplasty. Materials for trephined skulls are classified by their category. Individual parameters to describe their mechanical properties are collected and revealed in detail. The laboratory testing methodology for cranioplasty material is introduced to understand each parameter. At last, we discuss an engineering technique to look into the implant behavior. Since there is no standard goal for the biomechanical and biomaterial point of view for cranioplasty, this article suggests the finite element method for evaluation of the implant behavior and the degree of damage upon the impact injury. [Neurol Res 2001; 23: 267-276]

Cranioplasty: why throw the bone flap out?

Patients who undergo decompressive craniectomy for intracranial hypertension often require interval cranioplasty. Many cranioplasty agents are currently in use. The authors suggest that storage of the patient's own bone flap in the subcutaneous tissue of the abdominal wall, is a safe, efficacious and cost-effective alternative to use of synthetic cranioplasty materials.

A Method of Cranioplasty Using Coralline Hydroxyapatite

Introduction: Current cranioplasty materials include autologous or homologous bone grafts, wire mesh and methyl methacrylate, either alone or in combination. However, each material has its own unique disadvantages. Although hydroxyapatite has been used extensively in other specialties as a bone substitute, the coralline form has rarely been used to repair cranial bone defects. Coralline hydroxyapatite, similar to that found in bone, provides a matrix on which living tissue can form and grow. Because it is an ideal bioimplant, a method of cranioplasty using coralline hydroxyapatite was employed. Methods: The hydroxyapatite granules are mixed with Avitene and autologous blood to form a paste which can be countoured as needed. Results: Over the past few years, we have used hydroxyapatite either alone or in combination with tantalum mesh in 19 pediatric patients for a variety of conditions. The cosmetic results were good to excellent. Furthermore, postoperative CT scans have documented bony substitution of the hydroxyapatite granules. Follow-up ranged from 1 to 43 months with a mean of 26 months. Conclusion: In neurosurgical procedures when a bone substitute is needed, hydroxyapatite is an effective alternative to other currently available materials.

Experimental cranioplasty and skeletal augmentation using an α-tricalcium phosphate/dicalcium phosphate dibasic/tetracalcium phosphate monoxide cement: a preliminary short-term experiment in rabbits

Calcium phosphate cement consisting of α-tricalcium phosphate ( α-TCP), dicalcium phosphate dibasic (DCPD) and tetracalcium phosphate monoxide (TeCP) was implanted into surgically created full-thickness defects in the cranial bone (bone defect experiment) and directly onto the cranial bone under the periosteum (augmentation experiment). Three months after the implantation, the implants were retrieved with the surrounding tissues and studied histologically and micrographically to evaluate if the cement can be used as a cranioplasty and skeletal augmentation material. In the bone defect experiment, successful reconstruction of the defect was seen in 8 out of 12 specimens. Four specimens, where bleeding control was difficult at the time of implantation, showed partial loss of the cement. Histological and microradiographic studies of the successfully implanted cement revealed that new bone surrounded the implant nearly completely and united directly with the cement surface. In the augmentation experiment, the augmented area maintained the hemispherical shape and was connected tightly with the host bone. Histology and microradiography demonstrated that new bone formation was seen in the gap between the cement and the host bone, and on the outer surface (periosteum side) of the cement at the edge of the implant. From this preliminary short-term study, it could be concluded that the cement is a promising material for cranioplasty and skeletal augmentation with indications that it has good osteoconductivity.

Cranioplasty

We present our clinical experience in cranioplasty with autograft as follows: conchal cartilage for losses up to 2 cm2, outer table grafts for defects up to 100 cm2, and, for larger defects still, split rib grafts, which may be combined with outer table grafts. We conclude that autograft is superior to alloplastic material in cranioplasty.

Early Single-Stage Repair of Complex Craniofacial Trauma

The traditional surgical management of complex craniofacial injuries is performed in three stages: immediate craniotomy, orbitofacial repair in 7 to 10 days, and cranioplasty delayed 6 to 12 months because of the perceived risks of infection and prolonged anesthesia in the head-injured patient. Cosmetic considerations have always played a secondary role; however, there are reports that suggest that bone fragments and grafts can be safely placed even in contaminated wounds. In addition, advances in neuroanesthetic technique allow for prolonged administration of anesthesia without untoward effects on the patient. The purpose of this prospective study was to determine if early single-stage repair of complex craniofacial injuries could be accomplished with acceptable morbidity and mortality. In this study, 13 patients (9 men, 4 women) ranging in age from 3 to 53 years, with Glascow Coma Scale scores of 10 to 15, all had a combined single-stage repair of their complex craniofacial injuries within 24 hours of their trauma. After initial assessment and resuscitation, all patients were evaluated with computerized tomography of the face and head before surgery. Bicoronal skin flaps were used for maximum exposure for frontal sinus exenteration as well as dural repair, cortical debridement, and calvarial reconstruction. Dural grafts were necessary in 12 of 13 patients (92%), and supplementary bone grafting was required in 9 of 13 patients (69%), of which 3 of the 9 (33%) had iliac bone grafts, where split calvarial grafts were used in the other 6 of 9 (67%). No artificial cranioplasty material was used.(ABSTRACT TRUNCATED AT 250 WORDS)