Bone augmentation by replica-based bone formation.

OBJECTIVE: The sources of iliac crest bone grafts are limited. Alternatives are evaluated due to the progress in biomaterial sciences. Synthetical hydroxyapatite (HA), ß-tricalcium phosphate (ß-TCP) or biphasic compounds, or even a mélange of HA and ß-TCP will replace bovine ceramics. The goal is maintenance of replica-based-bone formation (RBBF) for bone augmentation. METHODS: 2 female and 2 male patients between 41 and 73 years with 5 sinus elevations were evaluated. Sinus elevations with lateral fenestration, trapezoidal-muco-periosteal flaps and filling with micro-chambered beads (1.5 mm) was performed. A porcine-collagenous membrane and the refixated flap covered the defect. A biopsy program over 20 months was confirm confirm the maintenance of the newly formed bone. RESULTS: A fast bone formation was pronounced. The biopsies revealed mature lamellar bone and full osseointegration of the ß-TCP implant. The biopsy after 20 months showed compact bone with osseointegration of minor rests of the ceramic implant. The defect revealed a mature bone stock already after 5 weeks. SIGNIFICANCE: The introduction of the replica-based-bone formation (RBBF) around micro-chambered beads will change the paradigm of bone augmentation. The next step of the ongoing study has to redefine the interval for implant insertion. The clinical approach confirms the breakthrough to primary mature lamellar bone formation and will permit reduction of placement time for a dental implant.

Formación de hueso esponjoso con esferas microcompartimentales / Primary cancellous bone formation around micro-chambered beads

Objetivo: Analizar el resultado del tratamiento y la evolución de los defectos en el hueso trabecular en pacientes tratados con cerámicas osteoconductivas. Material y métodos: Se estudiaron 10 reconstrucciones efectuadas en 9 pacientes (6 mujeres y 3 hombres) con defectos epifisarios y metafisarios, con una edad media de 49 (rango: 25-65) años en diferentes etiologías, 4 fracturas de tibia, 2 fracturas del calcáneo, una fractura patológica de metatarsiano, un condroma de fémur distal y 2 osteotomías de apertura. Los defectos se rellenaron con esferas de cerámica de _-fosfato tricálcico (_-TCP) e hidroxiapatita, de 4 y 6 mm de diámetro. El tiempo medio de seguimiento fue de 22 (7-48) meses. La evaluación de la reparación se realizó con radiografías y TC. Resultados: En todos los casos observamos la reconstrucción trabecular. Cuando el relleno era completo se observó la formación de hueso; por el contrario, si era incompleto no se apreció la formación de hueso trabecular. Las esferas fueron completamente reabsorbidas o integradas en el momento de la evaluación. Por su parte, las esferas de hidroxiapatita mostraron un mayor contraste en las imágenes, aunque se integraron en el esqueleto óseo. Conclusión: La formación primaria de hueso esponjoso se puede lograr con cerámicas osteoconductivas que se pueden combinar con cualquier tipo de osteosíntesis (AU)

Objectives: The question has been raised whether benign bone defects in patients can be treated with bone forming osteoconductive ceramics achieving primarily a cancellous bone scaffold, which is under load from the beginning Material and methods: Ten reconstructions were performed in 9 patients (6 women and 3 male), with a mean age of 49 (25-65) years, suffering a high variety of epi- and metaphyseal defects, four tibial fractures, two calcaneal fractures, one pathological phalangeal fracture, one chondroma of the distal femur and two open-wedge osteotomies were filled with micro-chambered ceramic beads of 4 and 6 mm in diameter. The mean follow up was 22 (7- 8) months. X-rays and CT-scans formed the basis for the evaluation of the reconstruction of the cancellous bone scaffolds. Results: All cancellous structures were rebuilt, if completely filled with bone-forming elements. If the filling was incomplete, no physiological cancellous bone scaffold resulted. The _-TCP micro-chambered beads were completely reabsorbed or sandwich-like incorporated at the time of evaluation. The HA micro-chambered beads revealed a contrast enhancement and were integrated in the osseous construction of the bone scaffold. Conclusion: Primary cancellous bone formation can be achieved with osteoconductive ceramic micro-chambered beads and can be combined with any osteosynthesis for stable fixation (AU)

[Primary cancellous bone formation around micro-chambered beads]. / Formación de hueso esponjoso con esferas microcompartimentales.

OBJECTIVES: The question has been raised whether benign bone defects in patients can be treated with bone forming osteoconductive ceramics achieving primarily a cancellous bone scaffold, which is under load from the beginning. MATERIAL AND METHODS: Ten reconstructions were performed in 9patients (6women and 3male), with a mean age of 49 (25-65)years, suffering a high variety of epi- and metaphyseal defects, four tibial fractures, two calcaneal fractures, one pathological phalangeal fracture, one chondroma of the distal femur and two open-wedge osteotomies were filled with micro-chambered ceramic beads of 4 and 6mm in diameter. The mean follow up was 22 (7- 8)months. X-rays and CT-scans formed the basis for the evaluation of the reconstruction of the cancellous bone scaffolds. RESULTS: All cancellous structures were rebuilt, if completely filled with bone-forming elements. If the filling was incomplete, no physiological cancellous bone scaffold resulted. The ß-TCP micro-chambered beads were completely reabsorbed or sandwich-like incorporated at the time of evaluation. The HA micro-chambered beads revealed a contrast enhancement and were integrated in the osseous construction of the bone scaffold. CONCLUSION: Primary cancellous bone formation can be achieved with osteoconductive ceramic micro-chambered beads and can be combined with any osteosynthesis for stable fixation.

Primary cancellous bone formation with BMP and micro-chambered beads: experimental study on sheep.

PROBLEM: The physiological reconstruction of cancellous bone defects in surgery of the locomotor system is an unsatisfactorily solved problem. AIMS: The aims of this study are to examine whether micro-chambered ß-tricalcium-phosphate (ß-TCP) beads provide a certain capillary force suctioning in blood and bone marrow thus forming a stable "negative"-replica of the bone marrow spaces. If so, a new approach for osteoconduction would yield primarily a scaffold of lamellar cancellous bone under load without a long-lasting remodeling process. Recombinant human bone morphogenetic protein (rhBMP) might even enhance all processes of defect healing, remodeling and ß-TCP resorption; gentamicin-loaded ε-caprolactone might protect the implant. MATERIAL AND METHODS: Ten sheep were operated on; the patella-groove model and the tibial head were used. A defect of 9.4 × 20 mm was created using wet-grinding-diamond instruments. Micro-chambered ß-TCP-beads of 4-6 mm with 0.35 mg rhBMP-7 + 0.1 g collagen per animal, or 1.5 g demineralized bone matrix (DBM) paste on the contra-lateral side were implanted. Both osteoinduction groups were compared with the defect in the tibial heads where plain micro-chambered ceramic beads were inserted. Added to the beads was 12.5 mg gentamicin sulphate in 12.5 mg ε-caprolactone-carrier. Outward diffusion was prevented using a 1-mm-thick press-fit inserted ceramic lid. The bone healing, remodeling and resorption of the ceramic in a right-left comparison of the patella groove and the tibial head was examined at 6 weeks, 2 and 3 months; one animal in reserve was followed for 14 months. The animals were perfusion-fixed, the vasculature micro-casted with an acrylate and nondemineralized processed, and with µ-CT and microscopically documented. RESULTS: A primary load-bearing spongiosa had developed around the beads, which shortened the remodeling process. The strong micro-chambered, resorbable ß-TCP-beads demonstrate high capillary strength, resorb blood and bone marrow, and represent a stable formative material which, as a carrier for the controlled local release of BMP, that accelerates bone healing, shortens resorption and remodeling compared with plain and DBM loaded implants. CONCLUSION: Micro-chambered beads represent the bone-forming element, BMP yields a fast defect healing and enhanced remodeling of bone and resorption of ß-TCP compared to delayed and incomplete reconstruction and resorption of ß-TCP on the DBM-side, the plain implants reached nearly the same reconstruction, but far later compared with the BMP loaded implants.