Comparison of the Visibility of Canine Menisci before and after Tibial Plateau Leveling Osteotomy: 3D-Printed Model Study

Cranial cruciate ligament (CCL) insufficiency is a common condition in dogs, commonly treated using tibial plateau leveling osteotomy (TPLO). CCL injury often results in secondary abnormalities of the menisci. Arthrotomy is still used by many veterinarians to detect meniscal damage, and also, before TPLO an assessment of the menisci is generally recommended. However, only a limited part of the menisci is visible during arthrotomy of the stifle. Our hypothesis was that the change in tibial plateau position created by TPLO allows a better visual access to the menisci. To verify suspicion, we compared the degree of visibility of the lateral and medial menisci before and after TPLO on 15 identical 3-dimensional (3D)-printed models of a normal canine tibia. On each model, the meniscal area was stained and photographed, and its part visible to the surgeon before and after TPLO was digitally measured and compared. Our modeling showed that before TPLO, without additional instrumentation, e.g., arthroscopy, only approximately 16% of the entire meniscus area was visible. We demonstrated that TPLO increased the visibility of the lateral meniscus to 38–56% (mean ± SD: 46.5 ± 5.4%) of its entire area and of the medial meniscus to 41–70% (mean ± SD: 52.8 ± 7.6%). This increase in the visibility was statistically significant (p < 0.001). We conclude that performing the examination of the menisci after TPLO allows for a review of about 50% of the entire meniscal area, in contrast to examination before TPLO, where only about 16% is visible. The visible area is slightly smaller in the lateral than in the medial meniscus; however, this difference is unlikely to be clinically relevant. Abstract The aim of this study was to compare the degree of visibility of the lateral and medial menisci before and after tibial plateau leveling osteotomy (TPLO) on 3D-printed models created after laser scanning of the right tibia with menisci derived from a fresh cadaver of a 4-year-old adult male golden retriever. The models were produced of white polylactic acid, and the menisci were filled with light-curing red resin. The models showed a similar conformation as the natural specimen harvested from the cadaver, maintaining the same length and width, in addition to reproducing the anatomical structures. From the pre- and post-TPLO radiographs, it was possible to identify the anatomical structures corresponding to the tibial plateau. The preoperative tibial plateau angle was 26.2°, and the postoperative one ranged between 4.0° and 5.3° (4.6 ± 0.4°). In the bird’s-eye photo, the total number of red pixels in the lateral and the medial meniscus was 2,053,995 and 2,140,939, respectively. Before TPLO, only between 14% and 19% of the entire area of the menisci was visible, and the unhidden part of the entire area of the meniscus before TPLO did not differ significantly between the lateral (16.2 ± 1.6%) and the medial (16.4 ± 1.6%) meniscus (p = 0.351). The visible part of the entire meniscus area increased significantly after TPLO both in the lateral and medial menisci (p < 0.001)—mean difference ± SD of 30.3 ± 4.3% (CI 95%: 27.9%, 32.6%) and 36.4 ± 6.4% (CI 95%: 32.9%, 40.0%), respectively. In conclusion, the intraoperative examination and treatment of dog menisci are easier after TPLO.

Accuracy of Instrument Portal Placement Using a Custom-Made 3D-Printed Aiming Device versus Free Hand Technique in Canine Elbow Arthroscopy

Elbow arthroscopy is commonly performed in canine’s orthopedics. During this procedure, two portals are required: one to insert the arthroscope, and the second one for surgical instruments. Establishment of an instrument portal is challenging due to limited visibility (via the arthroscope), and little free space inside the joint. To make this procedure easier, the goal of this study was to create a 3D-printed prototype of a device aiming the needle preceding the portal, and to check its feasibility on 15 canine cadavers of different sizes and breeds. On each cadaver, the procedure was performed on both elbows—one using the prototype, and the second one with a free hand. The two techniques were compared according to the mean number of attempts needed to achieve an optimal position of the instrument portal. We conclude that the use of the prototype increases the likelihood of the needle guiding the portal into entering the joint properly during the first attempt, making the arthroscopy less traumatic. Abstract While the insertion of the arthroscope into the elbow joint is relatively easy based on anatomical landmarks, obtaining a correctly located instrument portal is often difficult. Therefore, the goal of the study was to create a 3D-printed prototype of an aiming device for the guiding needle, and to check its feasibility. The study included fresh cadavers of 15 dogs, 9 males and 6 females, aged from 1 to 6 years (median 4 years) with body weight from 17 to 57 kg (median 30 kg). On each dog, we compared the number of attempts needed to obtain optimal direction of the guiding needle for the portal, using one elbow the prototype, and performing this as control on the opposite joint without the prototype (with a free hand). The number of attempts needed was significantly lower using the prototype (median 1) than on the control elbows (median 2, p = 0.009). The number of attempts was not correlated with the body weight neither in the case of experimental (Rs = 0.18, p = 0.532) nor control elbows (Rs = 0.13, p = 0.642). We conclude that the used prototype seems to be helpful in elbow joint arthroscopy.

Comparison of the Ventral Approach to the Canine Hip Joint Using Gelpi Retractors and an Elastic O-Ring Wound Retractor

Currently, there is an increasing emphasis on modifying surgical techniques to reduce iatrogenic damage to the patient’s tissues. Therefore, the aim of our study was to compare the surface area of the surgical wound bed after implementing the ventral approach to the hip joint using two orthogonally inserted Gelpi retractors and an O-ring elastic wound retractor (O-WR). Self-retaining metal retractors, such as Gelpi retractors, are potentially dangerous and can damage retracting tissues. Unlike Gelpi retractors, the O-WR is an atraumatic, self-retaining retractor. Such a device can be an alternative to metal retractors and other methods of soft tissue retraction such as stay sutures. This study included adult large breed dog cadavers. For each cadaver, two hip joints were accessed via the ventral approach without pectinectomy. After retraction of the wound with the pair of Gelpi retractors or the O-WR, digital photographs were taken, with a ruler placed next to the wound. The final step of the analysis was to compare the surface area of the surgical wound bed obtained after the use of Gelpi retractors and the O-WR. In this study, the O-WR provides the same surgical wound bed area as the most commonly used Gelpi retractors. Abstract This study included 10 fresh adult cadavers of large breed dogs (6 males and 4 females). Their weight ranged from 25 to 45 kg (mean ± SD: 33.9 ± 6.2 kg). The breeds represented were crossbreed dogs (n = 5), German shepherds (n = 2), Bernese mountain dogs (n = 1), American Staffordshire terriers (n = 1), and Gordon setters (n = 1). Access to the target area and identification of the femoral head and neck was achieved with two Gelpi retractors inserted orthogonally and with the O-WR in all procedures. In each dog, the approach to the hip joint was made on the left and right sides. There was no significant difference in the area of the surgical wound bed between the two sides using either the Gelpi retractors (−0.52 ± 1.87 cm²; CI 95%: −1.86, 0.81 cm²; p = 0.398) or the O-WR (−0.27 ± 2.34 cm²; CI 95%: −1.94, 1.41 cm²; p = 0.729). The area of the surgical wound bed was 6.28 ± 1.72 cm² (2.72–9.70 cm²) for the Gelpi retractors and 6.34 ± 1.81 cm² (4.13–10.77 cm²) for the O-WR, and the difference between the Gelpi retractors and the O-WR was not significant (−0.06 ± 1.72 cm²; CI 95%: −0.86, 0.74 cm²; p = 0.879)

Long bone models with artificial soft tissue envelope – MIPO training phantoms development

Minimally invasive plate osteosynthesis (MIPO) is a surgical culture of respect to the bone and soft tissue biology. This means that a bone plate is placed through relatively small skin incisions with as little dissection and stripping of the soft tissue envelope in the fracture’s neighborhood as possible. Minimally invasive plate application and fixation are demanding techniques. Percutaneous fracture fixation employs three basic principles: percutaneous reduction, extraperiosteal placement of the plates and bridging or contact fixation. The MIPO learning curve is steep and mastery of this technique requires training on bone models and cadavers. In present study, surgical phantoms dedicated to simulating MIPO on canine long bones were developed and tested. Based on the results of a CT scans of the large breed dogs’ long bones (humerus, radius and ulna, femur, tibia and fibula) mate for reasons unrelated to this study, using DICOM image segmentation and 3D modeling techniques, accurate models of bone structures were created. The next step was to work on modeling the geometry of the soft tissue envelope, which is the outer layer of the surgical phantoms. Using CT data, soft tissue models were developed and then simplified to enable the creation of casting molds. Using Fused Deposition Modelling (FDM) 3D printing technology, physical models of bone were produced. A high-temperature Nylon-based polymer infused with radiopaque compound to increase the visibility of bone structures during X-ray examination was used. Series of X-rays confirmed good visibility of external shape and internal structures needed for surgical training outcomes assessment. Functional tests were carried out on bone models casted with a polymeric material mimicking soft tissue envelope. The tests included cutting and stretching of soft tissue-alike plastic, drilling, cutting and breaking the bones mimicking models and minimally invasive plate osteosyntheses. In conclusion, it should be emphasized that long bone models with artificial soft tissue envelope can be useful in the process of learning MIPO.

Comparision of ventral approach to hip joint obtained by two gelpi retractors and o-ring elastic wound retractor – canine cadaver study

The ventral approach to the hip joint is useful for open reduction and fixation of femoral head fractures or femoral head and neck ostectomy (FHNO). The goal of this study was to compare the surface area of surgical wound bed after distraction by two orthogonally inserted Gelpi retractors and o-ring elastic wound retractor (O-WR). Fife mature canine cadavers free of coxofemoral joint pathology were used. All dogs were euthanized for reasons unrelated to this study. The weight of dogs ranged from 28 to 38 kg (mean 32,4 kg) and included two females and three males. For each cadaver two hip joints were reached via ventral approach without pectinectomy. The same cadaver was used to evaluate the two wound retraction methods in order to eliminate the variable of tensile strength of tissue between cadavers. After placing cadaver in dorsal recumbency the skin incision was made parallel to pectineus muscle beginning approximately over the hip joint and continuing approximately one-third of the length of the thigh. After freeing the fascia to the level of femoral artery and vein branches, separation between caudal margin of pectineus and adductor longus muscles was made. Subsequently deep wound retraction by two Gelpi retractors 130 mm long (Rudolf, Germany) placed orthogonally, the axial margin of the iliopsoas muscle was identified and elevated. Then the joint capsule was incised to reveal the femoral head and neck. At this point a photo with a ruler was taken. After removing the Gelpis an O-WR 60x70x150 mm (Ring ProtectTM, Grena, UK) was inserted. Tension of the sleeve was established by bringing the outer ring up to the inner one. After retraction of the wound with the O-WR a photo with a ruler was taken. Calibrated photographs made it possible to accurately convert pixels into actual measurement units. The next step was to mark the surgical wound bed area on a transparent layer overlaid on the picture. GIMP 2.10.34 software dedicated to image processing was used for this purpose. The marked area was colored blue, which made it possible to clearly identify the limits of the access and measure it precisely. Next, the calibration of the images was carried out. Based on the 5-cm section of the ruler present in each photo, the number of corresponding pixels was measured. The photos were scaled so that 5 cm corresponded to 500 pixels, which in practice meant that each pixel represented an area of 0.1 mm on a side. Once the images were rescaled, the number of pixels highlighted in blue was measured, which made it possible to precisely define the wound bed. The obtained results were expressed in pixels, but thanks to the previous calibration, they were directly converted to square millimeters. The final step in the analysis was to compare the surface area of the surgical wound bed obtained after use of Gelpis and O-WR. This was expressed as a percentage, allowing a direct understanding of the percentage by which the approach of one type differed from the other. Access to the target site and identification of the femoral head and neck was achieved with Gelpis and O-WR in all procedures. The results obtained were averaged to get mean value for access visibility improvement. Approach using the O-WR, on average, had a surface representing 119% in size with respect to the surface of approach obtained with two Gelpi retractors (representing the basis of the calculation and reference of 100%) - the improvement was therefore 19%. A truncated average was also calculated to obtain a more realistic final value for the improvement in access area. After discarding the extreme high and extreme low values, the surface area of the wound bed using the O-Ring averaged 116% with respect to the surface area obtained with Gelpis (representing the basis of the calculation and reference 100%) - the improvement was therefore 16%. The Gelpi is probably the most versatile self-retaining retractor in small animal surgery. The pointed tips of the blades in a Gelpi push the edges of the wound apart, and retain themselves in it, easing exposure of the surgical field. The blades could be potentially dangerous for vital structures. Pang et al. have described case of a girl with scoliosis who developed a massive hemothorax as a consequence of an injury of intercostal vasculature incurred by the Gelpi retractor used during surgery. One of the authors of this study (PT) has similar experience. While accessing the hip joint by ventral approach the blades of the Gelpi retractor can damage the medial circumflex vasculature. Another issue is that in many cases for good wound retraction the use of two Gelpis inserted orthogonally can be necessary. This makes the wound diamond-shaped, which can restrict access to the wound’s bed. Additionally, arms of Gelpi retractors lying inside the wound can limit the space for use surgical instruments, e.g. osteotomes, bone levers, rongeurs, etc. In contrast to Gelpi retractors once in position O-WR, static circumferential vision was archived with improvement of 16% of surface area of surgical wound bed. The expandable, circular structure of O-WR spreads the tension force evenly around the soft tissues and provides atraumatic retraction and wound protection over 360°. Circumferential elastic retraction maximizes the working area for better visualization and increased exposure. Thin and elastic elements of the retractor lying inside the wound do not interfere with potentially used surgical instruments.

Application of 3D Printing Technology for the Treatment of Intrahepatic Portosystemic Shunt in Dogs

Portosystemic shunt (PSS) is a vascular anomaly of the liver which provides direct communication between the portal venous supply and the systemic circulation, bypassing the liver. This results in a variety of life-threatening biochemical and clinical abnormalities. Congenital PSS most commonly occurs as a single extrahepatic (EHPSS) or intrahepatic (IHPSS) abnormality. EHPSS can be usually visualized by diagnostic imaging and during laparotomy performed in order to attenuate the shunt. In contrast, surgical identification of an intrahepatic shunting vessel can be challenging. This report of 3 cases describes the application of printed 3-dimensional (3D) technology in order to obtain a printed liver model before the surgical treatment of dogs with IHPSS. Three client-owned dogs with IHPSS diagnosed using CT angiography were included in this study. Triangular mesh models obtained by segmenting Digital Imaging and Communications in Medicine (DICOM) CTA images of the patient were preprocessed to prepare files for 3D printing. Through 3D volume and surface rendering, the vascular anomaly of each dog was identified in detail. Then, a patient-specific 3D liver model was printed and used for both preoperative planning, and intraoperative identification of the shunt. The model was manufactured using fused deposition modelling (FDM) technology in the form of lobes in partial cross-section to provide better visibility of the vascular pathology. In each case, the model enabled precise localization of the intrahepatic shunting vessel, which allowed open shunt attenuation using an ameroid constrictor in one dog, and cellophane banding in 2 remaining patients. All three treated dogs showed good recovery without complications. The 3D technology proved to simplify the planning of the surgery, and the intraoperative identification of the shunt made ease in all patients. The use of 3D technologies in small animals has many advantages: bone models, drill and saw guides, etc. In soft tissue surgery 3D patient individual liver models, scaled 1:1 is a helpful tool to facilitate learning and surgical planning and intraoperative navigation for dogs with IHPSS.

Three-Dimensional Models of Liver Vessels for Navigationduring Laparotomic Attenuation of Intrahepatic Portosystemic Shunt in Dogs

Laparotomic attenuation of an intrahepatic portosystemic shunt (IHPSS) is more difficult than an extrahepatic one, and results in a higher risk of complications because the identification of the aberrant vessel in the liver remains often a challenge. Excessive preparation and traction of the parenchyma results in trauma, bleeding, and prolonged surgery, which is what worsens the prognosis. Therefore, based on computed tomographic angiography, we printed 3-dimensional (3D) individual patient liver models, scaled 1:1, and used them for surgery planning and as a guide during intraoperative identification of the shunt in four dogs with IHPSS. The advantages of the 3D technology are simple and precise planning of the surgery, fast intraoperative identification of the shunt, and low invasive dissection of the liver parenchyma. We conclude that 3D technology can potentially raise the recovery rate. To the best of our knowledge, this was the first application of 3D models in the surgery of canine IHPSS.

Impact of 3D Printing Materials on Bone Phantom Features

Bone drilling is a common orthopedic procedure used to produce drill holes for screw insertion to repair fractured bone. Hole quality depends not only on the drill geometry but also on the cutting parameters, drilling force, and drilling technique, therefore, skilled personnel are required to successfully perform bone drilling. The drilling process should limit the generation of heat (thermal energy) to avoid osteonecrosis caused by interrupted blood supply to bone tissue. Studies were performed to determine the optimal material type and infill percentage for fabricating bone phantoms via 3D printing. Phantoms made from PA, PLA, and PET were produced using different infill percentages. Our results show large differences in quality among certain materials and demonstrate that 3D printing can be successfully used for manufacturing bone phantoms.

Study of Physical Properties of Additively Manufactured and Post-processed 3D Porous Structures Intended for Implants

The work aimed to determine the effect of finishing porous three-dimensional structures manufactured with additive technologies such as Selective Laser Sintering (SLS) and Fused Deposition Modeling (FDM) on their physical properties. The work focuses on the influence of the material, type of surface treatment as well as the thickness and height of the strut forming the tested structures on their surface quality, the degree of porosity, and compressive strength. Moreover, the compatibility of the 3D printed porous structure to the developed 3D model designed in the CAD software was also analyzed. The test samples were made of polyamide PA12 (SLS technology) and PLA (FDM technology). Depending on the 3D printing technology used, the impact of different types of finishing was assessed. The scope of the research included: mass measurement, determination of geometrical features, porosity examination by gas pycnometry, macroscopic observations, and static compression test. The analysis of the obtained results showed that with the use of SLS technology, the 3D physical model is characterized by greater accuracy compared to the model manufactured in FDM technology. It was also found that the smaller the strut height and thickness of the porous 3D structure, the more compressive strength the structure has. In the case of finishing 3D printing, it was found that for SLS technology, sandblasting with glass beads is the optimal treatment, while for models printed by the FDM method - annealing.

Accuracy of CAD/CAM and 3D printing in the treatment of feline femoral neck fracture

The aim of this study was to investigate whether a CT scan provides accurate bone surface information for feline bone model development. The second part of study consisted of 3D printing of feline femoral bone models with and without femoral neck fractures (31-B1 and 31-B2 in AO VET classification), as well as the development and 3D printing of drill guides for treatment of femoral neck fractures. The study was carried out on eight models of femoral bones and four drill guides. Initially, trial models of the right and left femurs without neck fractures and trial drill guides were used. Radiographs showed that the use of the prototype guides made it possible to drill holes in the axes of the necks of the femurs. Then, after assessing the correct operation of the guides and improving their adhesion to the bone surface by smoothing the inner surfaces of the guide bases, final bone models without femoral neck fracture, models with fractures 31-B1 and 31-B2, and final drill guides were printed. All models featured a 2.7 × 30 mm positional cortical screw. Radiographs of the models, made after inserting screws, showed that the implants were placed as intended. Also in the longitudinal sections of the heads and necks of the femoral bones of the models without fractures, the implants were positioned in the intended places.

Colored Bone Map - 3D printed bone models representing safety zones for orthopedic training and surgery planning

Two-dimensional data obtained from X-ray or found in scientific articles or books require the surgeon to develop a mental three-dimensional image of the anatomy. 3D printed models can simplify this mental exercise and provide realistic and user-friendly portrayal of radiographic data but also be a handy tool in learning process, as well as reminder used during preparation for the surgery. Properly manufactured models suitable for disinfection or sterilization may be even used during the surgery, placed next to the patient in a role of anatomy map. On a basis of CT scan of healthy dog and cat, three-dimensional models of long bones and pelvises were developed with usage of medical segmentation software. Next, models were virtually colored representing safety zones intended to be used in external fixation surgery planning (long bones) or plates osteosynthesis (pelvises). Dog long bones colored regions were devised on a basis of J.M. Marti and A. Miller articles - Delimitation of safe corridors for the insertion of external fixator pins in the dog 1: Hindlimb & 2: Forelimb. Cat long bones colored regions and both dog and cat pelvises safety zones were developed on a basis of one of the authors knowledge and clinical experience. Virtual models were then printed using commercial multicolor 3D printer modified specifically for this purpose Above work allowed to create physical-colored models in 1:1 scale, suitable for disinfection and usage in medical application – both for learning and training, as well as surgery planning. Further development of manufacturing method allows to create models suitable for steam sterilization in 121°C intended to be used during the surgery as an anatomy map representing safety regions of specific bone

Semi Elastic Pelvis - MPO/DPO Training Development

Cadaveric dissection passed the test of time with its educational value widely accepted by experienced surgeons. Nonetheless, it may be difficult to prepare a set of specimens of the same size, age, sex and race, with the same pathology to provide training for a group of surgeons. Development of 3D printing and biomaterials technologies could potentially provide alternative tools for surgical training. The problem with MPO/DPO surgical training is the availability of puppies’ cadavers which are important for proper procedure simulation due to a need of ischium and pelvic symphysis flexibility. Moreover, simulator should allow to assess procedure outcomes in X-ray imaging, mimicking the images surgeon would obtain on living patient. On a basis of CT scan, pelvis model was segmented and postprocessed to get virtual representation of healthy dog anatomy. Internal structure mimicking cancellous bone and solid shell representing cortical bone was developed to provide density gradient across the model. Highly flexible Nylon with X-ray visibility modifiers was used to manufacture physical artificial bone using 3D printing technology. Further annealing below glass transition temperature of polymeric material allowed to obtain semi elastic model mimicking natural bone. Proper annealing and manufacturing process settings were found crucial to provide not only desired rigidity of the model, but also machining properties – drilling and cutting with surgical instruments without excessive material melting. A series of cuts was performed to verify usability of artificial bone in surgical training – both for MPO and DPO, as well as double sided osteotomy – combined MPO and DPO. Further series of X-rays confirmed good visibility of external shape and internal structures needed for surgical training outcomes assessment.

Tests of Threaded Connections Made by Additive Manufacturing Technologies

The aim of the work was to determine breaking strength of the threaded connection between produced in additive manufacturing technology threaded component (fitting) and steel screw. Samples made in Selective Laser Sintering (SLS) and Multi Jet Fusion (MJF) technologies were used. Depending on method of production, in this research two kinds of materials were applied. Polyamide PA12 and composite material made of polyamide with glass particles PA-GF in volume proportion 70% to 30% were used. The results give a base of the statement, that the printed threaded connection allows to obtain stable and durable connection, enabling practical application of that type of connection.

Comparative approach to knee endoprosthesis stem materials - static analysis of bone-implant system by the means of FEM

The main aim of this work was evaluation of the displacements, strains and stresses in components of knee endoprosthesis by means of Finite Element Method. The semiconstrained knee endoprosthesis instrumented into femur and tibia bones was chosen for the analysis. The first step was preparation of full knee endoprosthesis geometrical model which was developed on a basis of a real model. Using reverse engineering methods containing 3D scanning and post-processing, model was obtained and then modified due to analysis assumptions. To carry out an analysis it was necessary to develop a femur and tibia bone models, which were obtained from MRI scans. Next a grid for finite-element method calculations was generated for the geometrical model. Mesh was next optimized to obtain high quality elements along with simplification of calculations. Subsequently it was necessary to specify and set the edge conditions to reflect appropriately the phenomena taking place in the real system. The system was loaded with axial force from femur proximal joint surface to tibia distal joint surface in range of 500-2000N. Calculations were realized for endoprosthesis components made of chromium alloy for femoral joint surface part, UHMWPE for plastic sliding bearing and five different titanium alloys for endoprosthesis femoral part stem and tibial implant part – Table I. On a basis of obtained results, the highest values of reduced stress in endoprosthesis elements were observed in the stems of both femoral and tibial part. Stress in bone didn’t exceed its compression strength for all of chosen materials. The biomechanical analysis may form the basis for improving the geometry of analyzed endoprostheses and optimizing a selection of the mechanical properties of the material used to manufacture them.

Numerical Analysis of Taylor-Type External Fixator by Means of FEM

The main aim of this work was evaluate the displacements and strains and stresses in components of bone-fixator system using Finite Element Method. The Taylor-type fixator was chosen for the analysis as a one of the most technically advanced and the biggest therapy opportunities giving external fixator. Through the possibility of full and free manipulation of bone fractures (possible displacements and rotations in three independent planes) it is used in complex fractures therapy, complicated bones deformation therapy, distraction osteogenesis and much more. The first step was preparation of Taylor-type fixator geometrical model which was developed on a basis of a real model. To carry out an analysis it was necessary to develop a tibia bone model in which the fracture crack of 1mm breadth was simulated. Next a grid for finite-element method calculations was generated for the geometrical models. Subsequently it was necessary to specify and set the edge conditions to reflect appropriately the phenomena taking place in the real system. The system was loaded with axial force in range 100-1500N. Calculations were realized for fixator made of 316L steel. On a basis of obtained result, the highest values of reduced stress wereobserved in the fixator frame, in elements connecting telescopic strut with holder constrained in fixator full ring. For load F > 1400N the yield stress of frame material was exceeding, what could cause its damage. In turn, stress in bone didn’t exceed its compression strength. The biomechanical analysis may form the basis for improving the geometry of analyzed fixator and optimising a selection of the mechanical properties of the material used to manufacture them.