Evaluation of usage of silicon-doped hydroxyapatite ceramics for treatment of fragmented bone fractures in dogs

Abstract

None of the methods of osteosynthesis provides the consolidation of bone fragments which have lost contact with soft tissues. It makes extremely difficult treating of this type fractures. Bone defect between the fragments and absence of a primary biological matrix complicates revascularization, causes long-term life of the connective tissue and cells of cartilaginous phenotype in the fracture zone. It is leads to a long-term consolidation of the fracture. Composites of hydroxyapatite and calcium phosphates are considered as bioactive and therefore the most promising for bone defects replacing. The aim of this investigation was clinical, radiological and hematological evaluation using of silicon-doped ceramics for fragmented bone fractures in dogs. For study was chosen dogs with accidental fragmented fractures of tubular bones which treated by extracortical osteosynthesis method. Animal was divided into two groups. A bone defects were filled with ceramics (GTlKg-3) for experimental animal group (n = 7), while no filling of bone defects in control animal group(n = 7) was performed. Protocol of anesthesia included medetomidine, butorphanol tartrate and epidural anesthesia with 2 % lidocaine solution. Animals of the control group began to lean on the injured limb from the 12–15th day after surgery, while the animal of research group from the 8-9th day. Complete limb repair in dogs of the control group occurred on the 38–42th day, but such period for experimental group animals was shorter – 25–27th day after the osteosynthesis. X-ray investigation (60th day) of experimental group dogs showed new formed bone tissue with osteosclerotic zones without a periosteal reaction, bone tissue, with a normal view of the epiphyseal areas and the bone marrow cavity. This is evidence of localized reparative osteogenesis (within bone trauma only), and completed fracture consolidation. At the same time in cases of the control group we found lower X-ray density of new bone, periosteum was thickened with excessive proliferation of the endosteum, especially below the site of bone injury. Thus, in case the absence of hydroxyapatite matrix in bone defects there were compensatory increasing proliferation of periosteum and endoosteum. Fragmented fractures of tubular bones in dogs have occurred by erythrocytopenia, that quickly disappear due to the reparative osteogenesis in dog of experimental group. These animals have had leukocytosis increasing due to the first three days after osteosynthesis as a reaction to the implantation of a calcium-phosphorus composite material. Dogs of control group have had second wave of leukocytosis increasing on forty-second day associated with elongated remodeling process. Areparative osteogenesis can be accelerated in 1.5 times in case of replacement of bone defects with silicon doped hydroxyapatite ceramics. It is possibility realized thru moderate reduction of active phase of inflammation and acceleration of proliferative phase, mainly from endosteum side with early mineralization of bone regenerate. The dynamics of hematology parameters is a typical for the tubular bone consolidation that indicates about moderate inflammation and demonstrate biological tolerance of silicon-doped hydroxyapatite ceramics.