Surgical treatment of congenital pseudarthrosis of the tibia bones is accompanied by a significant percentage of complications and refractions. One of the main reasons for the unsatisfactory results of treatment is the violation of the quality of bone tissue in the area of pseudoarthrosis, which is an obstacle to the normal process of fusion of the shin bones. Рurpose - use computed tomography to examine bone density in patients with congenital pseudoarthrosis of the tibia before and after surgery. Materials and methods. CT scans of the tibia of three patients with congenital pseudoarthrosis of the tibia, aged 5 to 7 years. The density in the Hounsfield units of the cortical layer above and below the nonunion zone was determined. Results. Prior to treatment, a significant decrease (p=0.001) in the density of the cortical layer of the tibia of the injured limb along its entire length was determined. One year after surgery, a statistically significant difference in the density of the cortical layer of the tibia remains. The optical density of the cortical layer of the damaged tibia is statistically significantly less than healthy (p=0.001). One year after surgical treatment by osteosynthesis with an intramedullary rod with axial mobility, the difference in the density of the cortical layer of the tibia of the healthy and operated limbs remains statistically significant (p=0.001) less than the bone density of the healthy limb. On the unoperated limb, a significant (p<0.05) increase in optical density of bones was observed in all studied areas. Conclusions. As a result of surgical treatment of congenital pseudoarthrosis of the tibia, there is a statistically significant increase in the density of the cortical layer. The density of the cortical layer of the bones of the operated shin a year after surgery is close to the density of the bones of a healthy limb. The increase in bone density of the operated limb is due not only to the growth of patients, but also occurs due to the possibility of loading the operated limb. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of the participating institution. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the authors.
Congenital pseudarthrosis of the leg bones is accompanied by its shortening and deformation. It’s still unclear what is an optimal method of surgical treatment. Objective. Using a mathematical model, to study the relative deformations of the regenerate (RDR) in the zone of pseudarthrosis bones of the lower leg under different options of osteosynthesis. Methods. The zone of nonunion was modeled of the bones of the lower leg third of tibia and 4 variants of osteosynthesis on were analysed: intramedullary rod and needle (1); rod, spoke and bone graft in the form of a block on the tibia (2) or on both (3) bones; rod, spoke and bone with a graft on both bones of the leg with wrapping titanium mesh (4). A rotationally stable and unstable rod was used. Under the influence of the load on compression and torsion determined the values of RDR in the zone of pseudarthrosis. Results. In the case of osteosynthesis of option 1, intramedullary rods of both types (due to axial mobility of their elements) do not provide minimal deformation regenerates of both bones, so there is a possibility of their growth during the growth of the patient. Bone blocks grafts (options 2 and 3) take over part of the compressive load and the level of the RDR of the bones decreases up to 20 times. Rotationally stable rod is better under conditions of torsional loads, since RDR of the tibia is reduced by 20 times. However, bone graft blocks negate this advantage, providing rotational stability of bone fragments lower legs. The use of titanium mesh provides an additional strength of fixation of fragments of both tibia bones and level RDR of bones is reduced by 10 % compared to models of osteosynthesis with a block of grafts for both loading options. Conclusions. The use of only intramedullary rods that «grow» leads to the greatest deformations of regenerates. A rod with rotational stability is better under torsional loading conditions. Blocks from bone grafts reduce the level of RDR of bones tibia to a level of less than 0.1 % for both loading options, and the titanium mesh to an additional 10 %.
Defects in the establishment and development of the cruciate ligaments are one of the main causes of the instability of the knee joint in congenital longitudinal defects of the development of the lower limbs. This pathology occurs with a frequency of 0.017 per 1000 newborns. The absence of cruciate ligaments leads to a change in the shape of the articular surfaces of the knee joint, and is formed due to hypoplasia of the femoral condyles, the absence of the intercondylar fossa of the femur, and the absence of the intercondylar elevation of the tibia. Purpose - to study the stressed-deformed state of the knee joint with aplasia of the cruciate ligaments before and after reconstructive interventions and to compare the obtained results with the norm. Materials and methods. A basic finite-element model of the lower limb was developed, which was supplemented with collateral and cruciate ligaments of the knee joint. On the basis of the basic model, a model with aplasia of the cruciate ligaments of the knee joint and a model reflecting the state of the knee joint after reconstructive surgery using the SUPER KNEE method according to D. Paley were developed. The model was tested under the influence of a vertical load in the position of bending the knee joint at an angle of 135. Results. The results of the mathematical modeling showed that the aplasia of the cruciate ligaments leads to an increase in the stress level, both in the bone elements of the model and in the elements of the ligamentous apparatus. Restoration of the ligamentous apparatus of the knee joint with artificial materials according to the SUPER KNEE method according to D. Paley allows to reduce the stress level in the bone elements of the model, while the stress in the femur is determined to be lower even compared to the normal model. Ligaments made of artificial material assume the main loads in the knee joint, and ensure an even load of mylar tape on both sides of the joint. The high level of stresses in mylar tape compared to normal ties is due to the higher modulus of elasticity of the material and its lower plasticity. Conclusions. Aplasia of the cruciate ligaments leads to an increase in the stress level, both in the bony elements of the model and in the elements of the ligamentous apparatus. Restoration of the ligamentous apparatus of the knee joint allows to reduce the stress level in the bony elements of the model with ligament aplasia, and brings the values closer to the parameters of the normal model. Tensions in the ligamentous apparatus of the knee joint after its restoration increase significantly, which is due to the mechanical properties of the artificial material that replaces the ligaments. The increased level of stress that occurs in the mylar tape indicates that it firmly holds the load arising in the joint. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of the participating institution. No conflict of interests was declared by the authors.
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