Peculiarities of bone regenerate formation, structural changes in joint cartridge and tibial nerve in the conditions of 3-mm automatic distraction of the tibia with the Ilizarov method and application of achillotomy (experimental study)

Introduction Reduction of the period of limb lengthening with the Ilizarov method and preservation of limb functions in large elongations are the tasks to be solved by modern traumatology and orthopedics. The aim was to study the functional state of the limb, dynamics of the tibial regenerate formation, histostructural changes in the articular cartilage and the tibial nerve under the conditions of automatic high-frequency elongation of the tibia with the method of transosseous distraction osteosynthesis at a rate of 3 mm using a preliminary Z-shaped achillotomy. Material and methods The 24-hour high-fractional mode provided with automatic distractor was used to lengthen tibiae of 12 adult mongrel dogs with the method of transosseous distraction osteosynthesis. Distraction rate was 3.0 mm per day in 120 steps. To prevent formation of foot equinus, a Z-shaped achillotomy was performed. Methods of light microscopy, morphometry and X-ray electron probe microanalysis were used to study the distraction regeneration in the tibia, the articular cartilage of the medial condyle of the femur and the tibial nerve. Results During the periods of distraction and fixation, the regenerate was characterized by a normotrophic structure with a large proportion of bone component which provided the limb support function after 45 days of the experiment. Thirty days after the removal of the apparatus, a newly formed bone of a typical structure was seen in the distraction gap. Achillotomy helped prevent equinus deformity of the foot and flexion contractures of the knee joint and the metatarsal joint. However, histostructural changes in the articular cartilage were detected at the stages of osteosynthesis. Despite the restoration of the thickness of the cartilage, there was a decrease in the number of isogenic groups and the presence of cells with chondoptosis by the end of the experiment. Not a single case of neuropathy of the tibial nerve was revealed histologically due to prevention of overstretching of the anterior surface of the tibia by an increase in the length of the calcaneal tendon with tenotomy. The proportion of destructively altered nerve fibers in all animals did not exceed 5 %. Necrobiotic changes in the epineural vessels were compensated by hypervascularization of the epineurium and endonevria, as a result of which the majority of nerve conductors retained their normal structure, numeric density, and restored dimensional characteristics at the end of the experiment. Conclusions The conditions of the experiment provide for functional restoration of the limb, promote active reparative osteogenesis and structural adaptation of the tibial nerve, do not cause any gross destructive changes in the articular cartilage and reduce the period with the Ilizarov frame on by 30 % as compared with the classical variant

Survival of percutaneous implants under various mechanical loading to the bone

Objective The purpose of the study was to explore bone formation processes and survival of percutaneous implants under various external compression of the bone. Material and methods 30 chinchilla male rabbits were used in the study. Tibia of the species was amputated at the upper third and an implant was surgically implanted with the distal part extending through the skin. A compression device was attached to the implant and loading provided to the bone next day after surgery. Five magnitudes of compression loading were used for animals subdivided into 5 groups comprising 6 species in each of the groups. Compression device with constantly maintained loading was attached to the limb during 6 weeks. Results Animals of groups I and II showed no case of the implant falling out throughout the whole period of observation. An implant fell out of the bone in one species of Group III after 56-day implantation, two and four species of Groups IV and V, correspondingly, 3 to 4 days after removal of compression device. Osseointegration was shown to improve in species of Groups I and II due to active angiogenesis in peri-implantation area. Conclusion Therefore loads of greater than 105260 Н/m2 applied to the bone result in decreased implant osseointegration whereas less intensive loading tends to improve osseointegratio

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

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

Abstract 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

Infestation of pine (Pinus sylvestris L.) seedlings with the pinewood nematode Bursaphelenchus xylophilus Steiner and Buhrer (Nickle) through wood sawdust

Abstract Key message There are various pathways for infesting pine trees with the pinewood nematode (PWN), Bursaphelenchus xylophilus. As a result of the experiment, we determined that sawdust infested with the nematode can pose a phytosanitary risk. Nematodes actively moved from infested sawdust into root or stem damaged pine seedlings. Context The spread of PWN, Bursaphelenchus xylophilus in pine plantations and forests is caused by beetles of the genus Monochamus, but the nematode can also be introduced via different coniferous commodities. Aims The study objective was to assess the possibility that injured roots and stems of Pinus sylvestris seedlings could be infested with PWN through nematode-infested sawdust. Methods Experiments of PWN infestation of pines were conducted in a climatic chamber at a temperature of 26 °C and moisture content of 60–70%. After a month in the climatic chamber, the seedlings were exposed to PWN through infested sawdust. Results It was determined that PWN actively penetrated seedlings with injured stems when directly exposed to PWN-infested sawdust (83% of seedlings (p < 0.012)). Similar results were obtained in the trial in which during planting, seedlings with damaged roots were exposed to PWN infested sawdust (50% of seedlings (p < 0.008)). The nematodes could not infest seedlings if the sawdust occurred on the soil surface at a distance of 2.5 cm from the seedling stem. Conclusion Our results indicate nematode infestation of pine trees can occur through PWN-infested sawdust