Impact of Transphyseal Elastic Nailing On the Histostructure of the Tibia in Growing Animals (Non-Randomized Controlled Experimental Study).

BACKGROUND: The use of intramedullary elastic nailing is a method of choice for prevention of complications in children with osteogenesis imperfecta. However, the morphology of the growing long bones in the conditions created was not investigated. AIM: The purpose of our experiment was to study the impact of elastic intramedullary nailing on the histostructure of long bones in their physiological growth. METHODS: Six mongrel dogs underwent intramedullary elastic transphyseal nailing of the intact tibia with two titanium wires. Six months after nailing, a light-optical microscopic and histomorphometric study of the operated and contralateral tibiae was performed. RESULTS: It was found that asymmetric lesion of the distal physis induces a decrease in the height of the distal epimetaphysis. Adaptive changes in the hyaline cartilage of both articular ends were revealed corresponding to the initial stage of chondropathy. Intramedullary nailing promotes an increase in the thickness of the compact bone and the volume of the trabecular bone. CONCLUSIONS: Elastic transphyseal nailing of the intact tibia has a shaping effect which is expressed by an increase in the volume of spongy and compact bone, adaptive changes in the hyaline cartilage. Asymmetric damage to growth zones should be avoided to prevent deformities.

Biological activity of the implant for internal fixation.

Early treatment of bone fractures was performed using implants, which are often used in the form of plates of various types, which are fixed on the bone surface (extracellular fixation) and nails that are located in the medullary canal (intracerebral fixation). The goal of this study was to investigate the features of osseointegration of implants for internal fixation (intramedullary or extramedullary) with various bioactive coating techniques. During experimental study on 20 mongrel dogs, the implant model in the form of 1.0-mm plate made of titanium alloy (Ti6Al 4V) was placed in the medullary canal (first series) or under the periosteum (second series): the plates had bioactive coating (hydroxyapatite) produced using the technology of magnetron sputtering (six animals), plasma electrolytic oxidation or microarc oxidation technology (PEO; eight animals), and composite technology (six dogs). Anatomic and histological studies have shown that the process of active osseointegration of porous implants with bioactive coating begins after 7 days: at first, granulation tissue - and then fibrous connective tissue - is formed; after 14 days, the osteogenic substrate can be found, and after 28 days, the entire implant area is covered by the lamellar bone tissue, which creates single implant-bone block. The most active formation of bone tissue is observed around implants with bioactive coating produced using the last two technologies. Low traumatic placement of porous implants with bioactive coating in the medullary canal or subperiosteally provides the stimulation of reparative osteogenesis and rapid (especially with PEO technique) osseointegration of the implant.

Bioactivity and osteointegration of hydroxyapatite-coated stainless steel and titanium wires used for intramedullary osteosynthesis.

A lot of research was conducted on the use of various biomaterials in orthopedic surgery. Our study investigated the effects of nanostructured calcium-phosphate coating on metallic implants introduced into the bone marrow canal. Stainless steel or titanium 2-mm wires (groups 1 and 2, respectively), and hydroxyapatite-coated stainless steel or titanium wires of the same diameter (groups 3 and 4, respectively) were introduced into the tibial bone marrow canal of 20 dogs (each group = 5 dogs). Hydroxyapatite coating was deposited on the wires with the method of microarc oxidation. Light microscopy to study histological diaphyseal transverse sections, scanning electron microscopy to study the bone marrow area around the implant and an X-ray electron probe analyzer to study the content of calcium and phosphorus were used to investigate bioactivity and osteointegration after a four weeks period. Osteointegration was also assessed by measuring wires' pull-off strength with a sensor dynamometer. Bone formation was observed round the wires in the bone marrow canal in all the groups. Its intensity depended upon the features of wire surfaces and implant materials. Maximum percentage volume of trabecular bone was present in the bone marrow canals of group 4 dogs that corresponded to a mean of 27.1 ± 0.14%, while it was only 6.7% in group 1. The coating in groups 3 and 4 provided better bioactivity and osteointegration. Hydroxyapatite-coated titanium wires showed the highest degree of bone formation around them and greater pull-off strength. Nanostructured hydroxyapatite coating of metallic wires induces an expressed bone formation and provides osteointegration. Hydroxyapatite-coated wires could be used along with external fixation for bone repair enhancement in diaphyseal fractures, management of osteogenesis imperfecta and correction of bone deformities in phosphate diabetes.