A glass fiber-reinforced composite - bioactive glass cranioplasty implant: A case study of an early development stage implant removed due to a late infection.

This case study describes the properties of an early development stage bioactive glass containing fiber-reinforced composite calvarial implant with histology that has been in function for two years and three months. The patient is a 33-year old woman with a history of substance abuse, who sustained a severe traumatic brain injury later unsuccessfully treated with an autologous bone flap and a custom-made porous polyethylene implant. She was thereafter treated with developmental stage glass fiber-reinforced composite - bioactive glass implant. After two years and three months, the implant was removed due to an implant site infection. The implant was analyzed histologically, mechanically, and in terms of chemistry and dissolution of bioactive glass. Mechanical integrity of the load bearing fiber-reinforced composite part of the implant was not affected by the in vivo period. Bioactive glass particles demonstrated surface layers of hydroxyapatite like mineral and dissolution, and related increase of pH was considerably less after two and three months period than that for fresh bioactive glass. There was a difference in the histology of the tissues inside the implant areas near to the margin of the implant that absorbed blood during implant installation surgery, showed fibrous tissue with blood vessels, osteoblasts, collagenous fibers with osteoid formation, and tiny clusters of more mature hard tissue. In the center of the implant, where there was less absorbed blood, only fibrous tissue was observed. This finding is in line with the combined positron emission tomography - computed tomography examination with (18F)-fluoride marker, which demonstrated activity of the mineralizing bone by osteoblasts especially at the area near to the margin of the implant 10 months after implantation. Based on these promising reactions found in the bioactive glass containing fiber-reinforced composite implant that has been implanted for two years and three months, calvarial reconstruction with the presented material appears to be a feasible method.

Paediatric cranial defect reconstruction using bioactive fibre-reinforced composite implant: early outcomes.

BACKGROUND: In children, approximately half of cryopreserved allograft bone flaps fail due to infection and resorption. Synthetic materials offer a solution for allograft bone flap resorption. Fibre-reinforced composite with a bioactive glass particulate filling is a new synthetic material for bone reconstruction. Bioactive glass is capable of chemically bonding with bone and is osteoinductive, osteoconductive and bacteriostatic. Fibre-reinforced composite allows for fabricating thin (0.8 mm) margins for implant, which are designed as onlays on the existing bone. Bioactive glass is dissolved over time, whereas the fibre-reinforced composite serves as a biostable part of the implant, and these have been tested in preclinical and adult clinical trials. In this study, we tested the safety and other required properties of this composite material in large skull bone reconstruction with children. METHOD: Eight cranioplasties were performed on seven patients, aged 2.5-16 years and having large (>16 cm(2)) skull bone defects. The implant used in this study was a patient-specific, glass-fibre-reinforced composite, which contained a bioactive glass particulate compound, S53P4. RESULTS: During follow-up (average 35.1 months), one minor complication was observed and three patients needed revision surgery. Two surgical site infections were observed. After treatment of complications, a good functional and cosmetic outcome was observed in all patients. The implants had an onlay design and fitted the defect well. In clinical and imaging examinations, the implants were in the original position with no signs of implant migration, degradation or mechanical breakage. CONCLUSIONS: Here, we found that early cranioplasty outcomes with the fibre-reinforced composite implant were promising. However, a longer follow-up time and a larger group of patients are needed to draw firmer conclusions regarding the long-term benefits of the proposed novel biomaterial and implant design. The glass-fibre-reinforced composite implant incorporated by particles of bioactive glass may offer an original, non-metallic and bioactive alternative for reconstruction of large skull bone defects in a paediatric population.

Outcomes of cranioplasty with synthetic materials and autologous bone grafts.

OBJECTIVE: Using current surgical methods, cranioplasty is associated with a high complication rate. We analyzed if there are preexisting medical conditions associated with complications and compared the effect of different implant materials on the degree of complications. METHODS: A retrospective review of the medical records of all patients who underwent cranioplasty for cranial bone defects during the period 2002-2012 was conducted, and 100 consecutive cranioplasty procedures that met eligibility criteria were identified. Patients were analyzed in 4 groups, which were created based on the cranioplasty material: autograft (n = 20), bioactive fiber-reinforced composite (n = 20), hydroxyapatite (n = 31), and other synthetic materials (n = 29). Survival estimates were constructed with Kaplan-Meier curves, and the differences between categorical variable levels were determined using a log-rank test. Multiple comparisons were adjusted using a Sidák correction. RESULTS: During a median follow-up time of 14 months (interquartile range 3-39 months), 32 of 100 patients (32.0%) developed at least 1 complication. A minor complication occurred in 13 patients (13.0%), whereas 19 patients (19.0%) developed a major complication, which required reoperation or removal of the implant. In the autograft subgroup, 40.0% of patients required removal of the cranioplasty. The 3-year survival of the autograft subgroup was lower compared with other subgroups of synthetic materials. In hydroxyapatite and bioactive fiber-reinforced composite groups, fewer complications were observed compared with the autograft group. CONCLUSIONS: Based on these results, synthetic materials for cranial bone defect reconstruction exhibit more promising outcomes compared with autograft. There were differences in survival rates among synthetic materials.

Craniofacial bone reconstruction with bioactive fiber-reinforced composite implant.

BACKGROUND: A novel, bioactive, fiber-reinforced composite implant is a solution to address the shortcomings in craniofacial bone reconstruction. A longitudinal clinical investigation with a follow-up time of 4 years was conducted. METHODS: A cranial bone reconstruction with the implant was performed on 12 patients. In these patients, the reasons for craniotomies resulting in craniofacial bone defects were traumatic and spontaneous intracranial bleeding as well as infections to the primary reconstruction material. The implant material consisted of a supporting fiber-reinforced framework, porous inner layers, and a bioactive glass (BG; S53P4) filling. The framework and the porous layers were made of a bisphenol-a-glycidyl methacrylate and triethyleneglycoldi-methacrylate (pBisGMA-pTEGDMA) resin matrix, which was reinforced with silanized E-glass. RESULTS: In clinical examinations and skull X-rays, the implants were in original positions providing the expected functional and aesthetic outcome at all time points. CONCLUSION: The implants functioned appropriately, which would provide a potential solution for craniofacial bone reconstruction in the future.

Novel composite implant in craniofacial bone reconstruction.

Bioactive glass (BAG) and polymethyl methacrylate (PMMA) have been used in clinical applications. Antimicrobial BAG has the ability to attach chemically to surrounding bone, but it is not possible to bend, drill or shape BAG during the operation. PMMA has advantages in terms of shaping during the operation, but it does not attach chemically to the bone and is an exothermic material. To increase the usefulness of BAG and PMMA in skull bone defect reconstructions, a new composite implant containing BAG and PMMA in craniofacial reconstructions is presented. Three patients had pre-existing large defects in the calvarial and one in the midface area. An additive manufacturing (AM) model was used preoperatively for treatment planning and custom-made implant production. The trunk of the PMMA implant was coated with BAG granules. Clinical and radiological follow-up was performed postoperatively at 1 week, and 3, 6 and 12 months, and thereafter annually up to 5 years. Computer tomography (CT) and positron emission tomography (PET-CT) were performed at 12 and 24 months postoperatively. Uneventful clinical recovery with good esthetic and functional outcome was seen. CT and PET-CT findings supported good clinical outcome. The BAG-PMMA implant seems to be a promising craniofacial reconstruction alternative. However, more clinical experience is needed.

Monitoring microvascular free flaps with tissue oxygen measurement and PET.

Tissue oxygen measurement and positron emission tomography (PET) were evaluated as methods for predicting ischemia in microvascular free flaps of the head and neck. Ten patients with head and neck squamous cell cancer underwent resection of the tumour followed by microvascular reconstruction with a free flap. Tissue oxygenation of the flap (P(ti)O(2)) was continuously monitored for three postoperative (POP) days and the blood flow of the flap was assessed using oxygen-15 labelled water and PET. In three free flaps a perfusion problem was suspected due to a remarkable drop in P(ti)O(2)-values, due to two anastomosis problems and due to POP turgor. No flap losses occurred. During the blood flow measurements with PET [mean 8.5 mL 100 g(-1) min(-1 )(SD 2.5)], the mean P(ti)O(2) of the flaps [46.8 mmHg (SD 17.0)] appeared to correlate with each other in each patient (p<0.05, n=10). Tissue oxygenation measurement is a feasible monitoring system of free flaps. The perfusion-study with PET correlates with P(ti)O(2)-measurement.

Bioactive glass hydroxyapatite in fronto-orbital defect reconstruction.

BACKGROUND: Synthetic bioactive ceramics and glasses have osteoconductive properties. These materials are capable of chemically bonding to the bone tissue. In addition, special bioactive glasses do not favor microbial growth. In this study, the clinical outcome of bioactive glass and hydroxyapatite in head and neck surgery was evaluated. METHODS: In a retrospective series of 150 patients, 62 patients underwent reconstruction with frontal sinus obliteration after chronic frontal sinusitis, 65 patients were operated on for fronto-orbital traumas, and 23 patients underwent reconstruction after fronto-orbital tumor resections. These patients were evaluated for surgical procedures, reconstruction materials, complications, and functional outcomes. RESULTS: Three of the 62 frontal sinus occlusions underwent operation (4.8 percent) during the follow-up of 5 years. The reoperations were caused by a new mucocele. In fronto-orbital reconstructions, we have reoperated on the orbital floor in four cases (7 percent). All 12 benign tumor patients and six of 11 malignant tumor patients survived during a follow-up of 3 years. Two of the 23 (9 percent) complicated tumor and trauma patients underwent reoperation because of a local mucocele. CONCLUSIONS: Treatment of severe head and neck defects with biomaterial is a suitable alternative to conventional methods. Bioactive materials seem to be stable and reliable at clinical follow-up. The reconstructions with bioactive glass and hydroxyapatite are associated with good functional and aesthetic results without donor-site morbidity. However, more long-term outcomes of studied biomaterials are needed to determine whether they are capable of competing with traditional tissue grafts.

Functional evaluation of microvascular free flaps with positron emission tomography.

BACKGROUND: The aim of this study was to assess blood flow (BF) of microvascular free flaps studied with positron emission tomography (PET) in patients with head and neck squamous cell cancer (HNSCC) undergoing major radical surgery 3-4 weeks after high-dose radiotherapy. METHODS: Five patients underwent resection of the HNSCC of the oral cavity followed by microvascular reconstruction with a radial forearm flap. Regional BF in oral and neck tissues was measured with PET using radiolabelled water ([15O]H2O) twice (1-2 and 12-14 days, respectively) following radical surgery. RESULTS: In the first postoperative PET study, the median BF in the cutaneous flap area was 5.1 mL/100 g/min, and in the muscle contra-lateral to the recipient site 19.9 mL/100 g/min. A low flap-to-muscle BF ratio appeared to correlate with circulatory incongruity, and thus with poorer flap success. The follow-up study on the second postoperative week supported the results of the primary PET scan. CONCLUSIONS: This pilot study suggests that PET using [15O]H2O is a feasible method to quantitatively evaluate BF of the whole free flap in patients operated on for oral