Development of Knowledge-Based Engineering System for Structural Size Optimization of External Fixation Device

The development process of the knowledge-based engineering (KBE) system for the structural size optimization of external fixation device is presented in this paper. The system is based on algorithms for generative modeling, finite element model (FEM) analysis, and size optimization. All these algorithms are integrated into the CAD/CAM/CAE system CATIA. The initial CAD/FEM model of external fixation device is verified using experimental verification on the real design. Experimental testing is done for axial pressure. Axial stress and displacements are measured using tensometric analysis equipment. The proximal bone segment displacements were monitored by a displacement transducer, while the loading was controlled by a force transducer. Iterative hybrid optimization algorithm is developed by integration of global algorithm, based on the simulated annealing (SA) method and a local algorithm based on the conjugate gradient (CG) method. The cost function of size optimization is the minimization of the design volume. Constrains are given in a form of clinical interfragmentary displacement constrains, at the point of fracture and maximum allowed stresses for the material of the external fixation device. Optimization variables are chosen as design parameters of the external fixation device. The optimized model of external fixation device has smaller mass, better stress distribution, and smaller interfragmentary displacement, in correlation with the initial model.

Analysis of the lower jaw exoskeleton in finite element programs

A special place in the methods of surgical treatment of bone fractures is occupied by transosseous osteosynthesis using external fixation devices of various designs.Objective: to analyze the lower jaw exoskeleton in finite element programs.Materials and research methods. During the research, 36 human lower jaws were involved from the museum of the Department of Oper-ative Surgery and Topographic Anatomy of the Volgograd State Medical University. They were scanned in 3D. All obtained images were loaded into a virtual scene reconstruction program. Fractures of the lower jaws in the corner area were modeled, an apparatus for external fixation of the lower jaw exoskeleton was installed, and the chewing load on the lower jaw was simulated. The place of application of the force was an area on a small fragment of a repositioned 3D model of the mandibular bone corresponding to the place of attachment of the masseter muscle. The evaluation of virtual studies was carried out according to the results of the stress-strain states of the bones and apparatus, the schedule of displacements of objects and the results of the analysis of the safety factor.Research results and discussion. In the course of evaluating the virtual placement of the mini-fixator wires of the apparatus for external fixation of the lower jaw exoskeleton, it was revealed that the main load is applied to the mini-fixator wires on a large fragment and the bone in the area of the wires. For the possibility of precise positioning of the osteofixers of the external fixation device, a device for the safe installation of the spokes of the lower jaw exoskeleton was also developed.Conclusion. Thus, on the basis of computer mathematical analysis, it can be argued that the developed design of the apparatus for external fixation of the lower jaw exoskeleton works under conditions of the maxillofacial region, performs reposition and fixation of bone fragments of the lower jaw under conditions of chewing functioning of the restored fracture of the lower jaw.

Development of a device for safe spatial orientation of the spokes of an extra-focal osteosynthesis apparatus

A special place in the methods of surgical treatment of bone fractures is occupied by transosseous osteosynthesis using external fixation devices.The aim of the study is to develop a device for the safe spatial orientation of the wires of the extrafocal osteosynthesis apparatus.Materials and methods. To develop a device for the spatial orientation of the external fixation spokes, a 3D model was designed with further reproduction on a 3D printer. The development of the device was carried out by placing the wires of the external fixation apparatus on 36 bones of the human lower jaw, on which a fracture in the angle was simulated.Results and discussion. The device for the spatial orientation of the spokes of the external fixation device for the lower jaw exoselet is partially reproduced using a 3D printer, which allows individualizing the device parts at the stages of preparation for surgery.Conclusions. Effect: control of the depth of immersion of osteofixers over the entire thickness of the bone and simplification of the choice of the optimal angle of mutual spatial orientation during their introduction and the greatest stable fixation of the fragments of the lower jaw during closed extrafocal osteosynthesis.

Adjustable, Skin-Stretching External Fixation Device and Negative Pressure Wound Therapy Application for Infected Full-Thickness Skin Defects: A Case Series Study

Introduction. Skin defects—especially infected, massive full-thickness defects—can be challenging to manage. Traditionally, defects are repaired using free flaps or musculocutaneous flaps. Many side effects and complications are associated with flaps, however, such as infection, pain, donor site pain, and poor cosmesis. Objective. This case series evaluates the use of an adjustable, skin-stretching external fixation device and negative pressure wound therapy (NPWT) to repair soft tissue defects. Materials and Methods. In this retrospective series, 7 patients with skin defects were treated with an adjustable, skin-stretching external fixation device and NPWT between January 2014 and December 2017. All patients were followed until complete healing was achieved. Each patient’s age, sex, defect size, mechanism of injury, healing time, results, and complications were recorded. Results. The average patient age was 37.43 years ± 10.47 SD (range, 26–55 years). The average skin defect area was 14.5 cm2 ± 5.26 * 23.25 ± 9.01 cm2 (range, 7–15 cm2 * 10–30 cm2), and average healing time was 3.29 months ± 1.60 (range, 1–6 months). All defects healed, and 2 patients developed ulcers. Conclusions. This series showed the adjustable, skin-stretching external fixation device and NPWT to be a simple, safe, and effective means of managing skin defects, with minimal complications.

Auto Strut: a novel smart robotic system for external fixation device for bone deformity correction, a preliminary experience

Purpose Several hexapod external fixators are used in the treatment of bone fracture and deformity corrections. One characteristic of all of them is the requirement for manual adjustment of the fixator struts. The purpose of this study was to introduce a novel robotic system that executes automatic adjustment of the struts. Methods Ten patients were treated for various bone deformities using a hexapod external fixator with the Auto Strut system. This new system automatically adjusts the fixator struts according to a hexapod computer-assisted correction plan. During each visit, the progress of the correction was assessed (clinically and radiographically) and reading of the strut scale numbers was performed and compared with the original treatment plan. Results All patients completed treatment during the follow-up period, achieving all planned correction goals, except from one patient who switched to manual struts due to personal preference. The device alarm system was activated once with no device-related adverse events. Duration of distraction ranged between ten and 90 days with a distraction index ranging between eight and 15 days/cm. Regenerate consolidation time between one and seven months. In total, 48 struts of eight patients were recorded and analyzed. In all, 94% of the final strut number readings presented a discrepancy of 0 mm to 1 mm between planned and actual readings, indicating high precision of the automatic adjustment. Conclusion This study presents preliminary results, showing that Auto Strut can successfully replace the manual strut adjustment providing important advantages that benefit the patient, the caregiver and the surgeon. Level of Evidence Level II

CONSOLIDATION OF FEMORAL FRACTURES AT APPLICATION OF DIFFERENT TREATMENT METHODS TAKING INTO CONSIDERATION DURATION OF THE PERIOD FROM TRAUMA TO OSTEOSYNTHESIS

Objective. To study the characteristics and healing duration of the diaphyseal femoral fractures, depending on the technologies used for osteosynthesis and the time between trauma and osteosynthesis. Methods. The study was performed on bred dogs (n=24). In the operating theatre all animals were modeled the transverse fracture of the femoral diaphysis in the middle third using a chisel. The animals were divided into 4 groups (6 per group). Animals of group 1 (one hour after the fracture) underwent transosseousosteosynthesis with a pin-rod external fixation device (PREF). In group 2, PREF was performed on the fourth day after the injury. In group 3 (one hour after the injury) blockable intramedullary osteosynthesis (BIOS) was performed. In group 4, the similar BIOS was performed on the fourth day after the fracture. To assess the results of treatment, the clinical, radiological and laboratory research methods were used. The duration of post-operative observation of the animals was 100 days. Results. It has been found out that the dynamics of osteoreparative processes in the studied groups was similar and did not depend on the time between trauma and osteosynthesis. The median time for the femoral shaft fracture healing in animals of group 1 was 46 days (Q1-Q3: 38-57), in group 2 - 73 days (Q1-Q3: 71-78) (differences between groups are significant at p=0.004); in group 3 - 49 days (Q1-Q3: 44-60), in group 4 - 72 days (Q1-Q3: 70-93) (differences between groups are significant at p=0.008). It is shown that the reason for the increase in fixation terms in dogs with the delayed osteosynthesis is the long-term persistence of the acute phase reaction caused by trauma (using the growth of C-reactive protein as an example). Conclusion. The healing terms of a femoral shaft fracture with the use of PREF technology and BIOS technology are comparable, both in the conditions of urgent and delayed osteosynthesis. What this paper adds It has been determined the similarity of the osteoreparation dynamics in the healing of diaphyseal femoral fractures: under conditions of osteosynthesis with a pin-rod external fixation device (PREF) and blocked intramedullary osteosynthesis (BIOS). For the first time it has been shown that healing terms of a diaphyseal femoral fractures when osteosynthesis performed in 4 days after injury is 1.5 fold longer in comparison with the performance of osteosynthesis within 1 hour after the injury. For the first time it has been shown that in the case of delayed osteosynthesis, the effectiveness of PREF and BIOS is comparable in terms of the duration of the consolidation of the diaphyseal femoral fractures.

Experience of using an original external fixation device in the treatment of pelvic fractures in a patient with polytrauma

The article presents a clinical case of a patient being treated after a road accident in the Kaluga Regional Clinical Hospital of Emergency Medicine named after K. N. Shevchenko, delivered by an ambulance team 1,5 hours later with a diagnosis: Polytrauma. Severe closed head injury. Brain contusion of moderate severity. Fracture of the pelvic bones. Lung contusion. Respiratory failure 1-2. Traumatic shock. Taking into account the severity of the patient’s general condition, we performed minimally invasive osteosynthesis of the pelvic bones with an external fixation device of the original design of spoke arrangement and CITO screw. After 2,5 months, fracture consolidation was diagnosed and the apparatus was dismantled. Then the patient underwent a course of rehabilitation and restorative treatment. At the end of the course of rehabilitation treatment, a good recovery of the patient’s functionality was noted. Key words: polytrauma, external fixation device of the original design, treatment tactics, injury control surgery.

Surgical treatment of transacetabular fractures

The article presents an analysis of the treatment results of patients with transverse acetabulum fractures of type B1.1 according to the AO classification using various surgical tactics/ the most optimistic results were obtained when using the hip joint osteosynthesis with an external fixation device (EFD) «pelvis-hip» in urgent cases. Besides the obvious antishock action, it allows removing the femoral head from the central displacement and in many cases achieving the reposition of the acetabulum, due to ligamentotaxis. After x-ray control in the case of a further incomplete reposition in the EFD, it significantly simplifies the open stage of surgical treatment after the stabilization of the vital functions of the body, which has a positive effect on the long-term results of treatment of this complex category of patients.