Comparison of the use of biocompatible materials and titanium in the treatment of midshaft clavicle fractures with a patient-specific plate: a finite element analysis study.

BACKGROUND: Clavicular midshaft fractures treated with titanium plates may encounter complications like implant failure. We assess if alternative biocompatible materials suchs as PLA, PLA/HA, PEEK offer comparable stability. Our study evaluates the biomechanical performance of these materials in surgical management of midshaft clavicle fractures. METHODS: We simulated a personalized fixation implant with four different materials and conducted finite element analysis in ANSYS to assess maximum von Mises stress (MvMs). RESULTS: The MvMs occurring on the plates, screws, clavicle, and fracture site were recorded. MvMs on titanium material at the 6th hole level (764.79 MPa) and the 6th screw level (503.38 MPa), with the highest stresses observed at 48.52 MPa on the lateral clavicle at the 1st hole level and 182.27 MPa on the medial clavicle at the 6th hole level. In PLA material analyses, the highest MvMs were observed at the 3rd hole level (340.6 MPa) and the 3rd screw level (157.83 MPa), with peak stresses at 379.63 MPa on the lateral clavicle fracture line and 505.44 MPa on the medial clavicle fracture line. In PLA/HA material analyses, the highest MvMs were at the 3rd hole (295.99 MPa) and 3rd screw (128.27 MPa), with peak stresses at 220.33 MPa on the lateral clavicle and 229.63 MPa on the medial clavicle fracture line. In PEEK material analyses, the highest MvMs were at the 3rd hole (234.74 MPa) and 6th screw (114.48 MPa), with peak stresses at 184.36 MPa on the lateral clavicle and 180.1 MPa on the medial clavicle. CONCLUSION: Our findings indicate that titanium material shows significantly higher stresses on plates and screws compared to those on the clavicle, suggesting a risk of implant failure. PLA and PLA/HA were inadequate for fixation. Although stress on the plate with PEEK material is higher than on the clavicle, it remains lower than titanium, indicating potential stability at fracture site. Further research is needed to confirm these findings.

Relationship between maxillary sinus mucosal cyst and sinus ostium 2D area in three-dimensional volumetric paranasal CT images.

OBJECTIVE: To investigate the relationship between the maxillary sinus ostium 2D area (SOA) and the development of mucosal cysts of the maxillary sinus (MMC). METHODS: Thirty patients (≥ 18 years) with unilateral MMC who underwent paranasal sinus CT (PNsCT) were included in this single-center retrospective study. Non-MMC sinus was used as the control group. Cyst and air volume of the maxillary sinuses, diameter, and 2-dimensional area of the ostium of the patients were calculated in the 3-dimensional volumetric analysis program. Both correlation and linear regression model analyses were performed for the relationship between MMC and SOA. RESULTS: Thirty patients were included (mean age of 42.30 ± 17.62 years). A total of 15/30 (50%) were male. The mean SOA in patients with MMC (8.91 ± 1.10 mm2) was lower than in patients without MMC (12.94 ± 1.35 mm2), which was statistically significant (p < 0.001). The mean sinus ostium diameter in patients with MMC (2.12 ± 0.71 mm) was higher than in patients without MMC (1.91 ± 0.82 mm), which was statistically insignificant (p = 0.295). There was a statistically significant, good level of negative linear correlation between SOA and total cyst volume (TCV) [correlation coefficient (r) = - 0.680, p < 0.001]). As a result, the regression model consisting of "Age, Sinus air volume, and TCV" variables is a good model and has statistically significant relations with SOA. CONCLUSION: In conclusion, small SOAs contribute to the development of MMC. There was a negative correlation between SOA and TCV. In addition, 2D area measurement may be a more accurate method instead of diameter measurement.

Olecranon fractures: A biomechanical comparison of three tension band wiring fixation methods on bone models.

PURPOSE: This study aimed to compare the biomechanical pull-out strength of the three different tension band wiring (TBW) methods employed to fix transverse olecranon fractures on bone models. METHODS: Three different fixation models were created in groups of seven synthetic olecranon fractured bone models. The first technique was fixed the olecranon with the traditional TBW method. The second technique was fixed the olecranon with a large intramedullary screw TBW method. The third technique was fixed the olecranon with the double-screw TBW method. The pull-out force needed for the failure of each specimen under the tensile test device was evaluated, and the results were recorded. RESULTS: We found that the lowest average pull out strength was 55.10 N (range: 35.87-65.85 ± 10.17) in the traditional TBW method, the highest pull out strength was 84.28 N (range: 63.67-117 ± 18.87) in the double-screw TBW method. The pull out strength was 70.80 N (range: 52.60-80.95 ± 10.18) in the intramedullary screw TBW method. In terms of ultimate failure loads, there was no significant difference between the intramedullary screw TBW and the double-screw TBW (p > .05) while there was a significant difference between the traditional TBW and the other two methods (p < .05). CONCLUSION: The use of screw(s) shows higher biomechanical stability than K-wires in the TBW method. Double-screws fixation gives similar results in terms of the biomechanical load to failure compared to a large intramedullary screw fixation. Both screw methods can be used as stable constructs in clinical practice. LEVEL OF EVIDENCE: III, biomechanical trial.

An analytical and numerical approach to the determination of thermal necrosis in cortical bone drilling.

In the process of repairing fractures in the bone region with orthopedic injuries, the application of supporting and strengthening the bone tissue with screws, wires, rods, and plates is a widely preferred internal fixation method. In this treatment process, it is necessary to drill the bone tissue to fix the screws. Due to the heat generated in the drilling process, mechanical and thermal damage occurs in the bone tissue. In this study, it is focused that the effect of different cutting conditions on the temperature distribution and necrosis zones in the drilling of human cortical bone. In this context, by selecting variable drill geometry (diameter, point angle, and helix angle) and variable cutting parameters (cutting speed and feed rate), temperature distribution and necrosis zones were investigated with finite element analyses and analytical calculations. When the findings were evaluated, it was understood that drill diameter and cutting speed did not have a significant effect on temperatures and necrosis zone at low cutting speeds. At high cutting speeds, it was observed that the feed rate and drill point angle had an indeterminate effect on the temperatures. The lowest temperature values were obtained at cutting speed of 750 rpm and a feed rate of 0.1 mm/rev for low cutting speeds, and cutting speed of 1500 rpm, helix angle of 10° and drill bit diameter of 2 mm for high cutting speeds. The narrowest necrosis zones were obtained at cutting speed of 250 rpm and feed rate of 0.1 mm/rev for both drill diameters. As a result, the effects of different drill geometry and cutting parameters were determined in order to obtain low temperature distribution and narrow necrosis zone in cortical bone drilling.

Traction therapy in lumbar disc hernias: A finite element analysis study.

OBJECTIVES: This study aims to evaluate the results of lumbar traction treatment at different traction angles and different traction forces using the finite element analysis (FEA). MATERIALS AND METHODS: Computed tomography (CT) images of a healthy 35-year-old male patient who had no history of trauma or fracture were modeled in three-dimensional (3D) with Mimics® software for the lumbosacral spine model. Ligaments and discs were created on the 3D spine model in the SolidWorks® program. The obtained model was sent to the ANSYS version 18 software, and analyses were done non-linearly. All analyses were performed at different angles and forces from the center of the sacral surface to simulate traction therapy. RESULTS: Traction forces applied in the 0° axial direction decreased the intradiscal pressures by creating a similar tensile stress in the annulus fibrosus regions (anterior, posterior, and lateral) without any significant change in lordotic angle. CONCLUSION: The method used in this study is promising to investigate the benefits of traction therapy. Moreover, individual traction force and direction can be determined to increase the effectiveness of the treatment by using magnetic resonance imaging or CT images in traction therapy.

3D volumetric evaluation of the diagnosis and severity of carpal tunnel syndrome using MRI.

BACKGROUND: Carpal tunnel syndrome (CTS) is the most common nerve compression syndrome. The usage of clinical tests and nerve conduction studies (NCS), as well as ultrasonography and magnetic resonance images (MRI), have recently become widespread to diagnose CTS. This study aims to determine the alteration of the carpal tunnel volume based on disease seriousness by MIMICS 19.0 which is a three-dimensional modeling software. MATERIALS AND METHOD: In this study, 80 wrists of 63 (47 female and 16 male) patients with MRI and NCS results among 1252 patients who applied to our hospital with wrist pain and neuropathic complaints between January 2019 and August 2020 were included in our study. The patients were classified into four groups according to their NCS results as normal, mild CTS, moderate CTS, and severe CTS. Carpal tunnel volumes of the groups were measured with MIMICS 19.0 program using MRI. Three-dimensional carpal tunnel volume averages were statistically compared between the groups. Then, all statistical analyzes were performed using SPSS (Statistical Package for Social Sciences, version 23) software. RESULTS: The results demonstrate the mean carpal tunnel volume values for normal, mild CTS, moderate CTS, and severe CTS are 5.51 cm3 ± 0.20, 5.27 cm3 ± 0.16, 4.86 cm3 ± 0.20, and 4.43 cm3 ± 0.24, respectively. Carpal tunnel volumes were found to be lower in all groups which have CTS compared to the normal group. As the groups with CTS were compared among themselves, a significant difference was found between the groups in terms of carpal tunnel volumes (p < 0.001). CONCLUSIONS: In this study, a significant relationship between 3-dimensional measurements of carpal tunnel volume and the severity of CTS was observed. Therefore, MRI is an applicable method to diagnose and determine the severity of CTS.

The importance of Böhler's angle in calcaneus geometry: A finite element model study.

OBJECTIVES: Calcaneal fractures are the most common tarsal fractures following a foot-ankle trauma. The Böhler's angle is an important measurable angle before, during, and after surgery. In this study, we aimed to investigate correlation between Böhler's angle, calcaneal strength, and subtalar joint stress using a finite element analysis (FEA). PATIENTS AND METHODS: Between January 2016 and December 2016, computed tomography (CT) scans were used with MIMICS® software for FEA. The ankle and foot of a 23-year-old male person with a height of 180 cm and weighing 80 kg was modeled as reference. Raw coronal CT images were obtained in Digital Imaging and Communications in Medicine format with the resolution of 512X512 pixels and 0.3-mm slice intervals in 135 kV. The structures including tibia, fibula and 26 other bones (talus, calcaneus, cuboid, navicular, three cuneiforms, five metatarsals, and 14 components of phalanges), cartilage and ligamentous tissues were modeled to form ankle joint. After determining Böhler's angle as 35 degrees for the reference model, a fracture line was created on calcaneus. Calcaneus was remodeled with the Böhler's angle of 45, 40, 30, 25, 20, 10, and 0 degrees respectively. All models were transferred to ANSYS software for FEA and the loads on the lower extremities with normal posture were applied on models. RESULTS: Analysis of all models based in the reference model revealed that maximum tension values on calcaneus increased, while the Böhler's angle decreased, indicating a statistically significant difference. The decreased Böhler's angle indicated statistically significantly higher maximum tension values (p=0.04). Action force in subtalar joint was evaluated by comparing with the forces in reference model. The increased Böhler's angle was found to be associated with statistically significantly decreased amount of load on subtalar joint. The decreased Böhler's angle was related to the statistically significantly increased amount of load on subtalar joint. CONCLUSION: Our study results suggest that decreased Böhler's angle increases the possibility of subtalar arthrosis, although overcorrection of the Böhler's angle seems not to increase the risk of subtalar arthrosis.

A rare presentation of panitumumab-involved interstitial lung disease: Spontaneous pneumomediastinum.

INTRODUCTION: Developments in targeted molecular therapies have considerably improved patient survival in cancer. Panitumumab is a monoclonal antibody against the epidermal growth factor receptor (EGFR). It is used to treat metastatic colorectal carcinoma. Although panitumumab is well tolerated in most patients, pulmonary toxicity, especially interstitial lung disease (ILD), is a life-threatening condition. The presentation of panitumumab-induced ILD with spontaneous pneumomediastinum and subcutaneous emphysema is rarely reported. CASE REPORT: We describe a 61-year-old male with metastatic colorectal carcinoma treated with FOLFIRI (folinic acid, 5-fluorouracil, irinotecan) and panitumumab. He presented to our hospital with a complaint of severe dyspnea. On the evaluation of dyspnea, the patient was diagnosed with ILD. MANAGEMENT AND OUTCOME: After exclusion of other common causes of pneumomediastinum and subcutaneous emphysema, panitumumab was attributed as a cause of ILD. Oxygen therapy via high flow nasal cannula and intravenous methylprednisolone regimen was started. After two weeks, the patient became asymptomatic with the radiologic amelioration. DISCUSSION: Panitumumab-induced ILD is associated with a poor prognosis and might occur randomly in one year after the drug administration. The possibility of the disease should be considered on every admission. Early recognition, discontinuation of causative medication, and immediate glucocorticoid therapy are essential to reduce mortality.

Comparison of two surgical techniques for the treatment of transverse olecranon fractures: A finite element study.

BACKGROUND: In this study, we aimed to compare the stability of traditional tension band wiring (TBW) and screw combined TBW (SC-TBW) fixation methods performed for a transverse olecranon osteotomy-fracture during different degrees of elbow movement by using finite element analysis. METHODS: Three-dimensional solid modeling of the olecranon was obtained by computed tomography images. Transverse olecranon fracture was created and fixed by TBW and SC-TBW with respect to triceps muscle force. Opening angle, twisting angle and interplanar translation occurring on the fracture line were evaluated at 45° and 90° elbow flexion. RESULTS: Opening angle: 0.71°, 0.87° at 45° and 0.64°, 0.67° at 90° elbow flexion for TBW and SC-TBW, respectively. Twisting angle: -0.01°, -0.19° at 45° flexion and 0.19°, 0.30° at 90° flexion for TBW and SC-TBW, respectively. Interplanar translation: 1.93 mm, 4.65 mm at 45° flexion and 1.78 mm, 3.95 mm at 90° flexion for TBW and SC-TBW, respectively. CONCLUSION: TBW fixation provides more stability than SC-TBW fixation model.

The Effect of 3D-Printed Custom External Nasal Splint on Edema and Ecchymosis After Rhinoplasty.

PURPOSE: The aim of this study was to investigate the effects of traditional thermoplastic splints vs a 3D-printed custom external nasal splint designed to apply pressure to the lateral osteotomy lines and neighboring periorbital region on edema and ecchymosis after rhinoplasty. PATIENTS AND METHODS: Forty patients undergoing open rhinoplasty were included in this prospective randomized controlled study. The patients were divided into 2 groups. In the study group, the new 3D-printed custom external nasal splint was used. In the control group, the thermoplastic external nasal splint was used. Periorbital edema and ecchymosis scores were assessed peroperative before external nasal splint application, postoperatively at the 1st and 4th hours, and 1st, 2nd, 5th, 7th, 10th, and 15th days. RESULTS: There were lower scores of ecchymosis and edema in the study group compared to the control group for all the follow-up controls. There was a significant difference between the 2 groups with respect to the occurrence of ecchymosis for all follow-up controls except for the first postoperative hour and the seventh postoperative day (P < .05). Comparison of the 2 groups with respect to the grade of edema showed a significant difference only in the first and fourth postoperative hours (P < .05). CONCLUSIONS: The study detected less edema and ecchymosis scores using this 3D custom external nasal splint, thus creating a new area of use for 3D printers in the field of facial esthetic surgery. New thermoplastic splints of different shapes and sizes can be produced that can compress the osteotomy lines and the neighboring periorbital region.

Evaluation of Cardiopulmonary Resuscitation Conditions in Turkey: Current Status of Code Blue.

OBJECTIVE: Globally, previously determined teams activated by 'code blue' calls target rapid and organised responses to medical emergency situations. This study aimed to evaluate the cardiopulmonary resuscitation (CPR) conditions in Turkey. METHODS: A web-based survey was sent to anaesthesiologists in Turkey via email. The survey included 36 questions about demographic features and 'code blue' practices and procedures. RESULTS: A total of 180 participants were included. The mean working duration was 16.1±7.5 years. Of the anaesthesiologists who participated, 35% worked in university, 26.1% in education and research, 1.7% in city hospitals, 18.9% in state hospitals and 18.3% in private hospitals; 68.3% had CPR certification. There were code blue systems in 97.6% of the organisations. For code blue calls, 71.9% were activated by calling '2222'. There were 41.5% organisations with code blue teams of 3-4 people, whereas 26.7% had 2-member teams. Among call responders, 68.5% were anaesthesia technicians/paramedics, 60.7% were anaesthesiologists and 42.7% were anaesthesia assistants. In organisations, 66.3% regularly conducted code blue training. In total, 63.3% of the participants stated that the time to reach the location was nearly 2-4 minutes. During CPR, the use of capnography was 18.3%. Of the participants, 73.8% chose endotracheal intubation as priority airway device during CPR. CONCLUSION: Today, code blue practice is an important quality criterion for hospitals. This study shows the current status of 'code blue' according to the results of respondent data completing the survey. To prevent in-hospital cardiac arrest, a chain of preventive measures should be established, including personnel training, monitoring of patients, recognition of patient deterioration, the presence of a call for help system and effective intervention.

Comparison of two methods for coracoclavicular ligament reconstruction: A finite element analysis.

OBJECTIVE: This study aimed to compare two different tendon grafting techniques for coracoclavicular ligament reconstruction from the data obtained using finite element analysis. METHODS: Three different finite element models of the shoulder girdle were formulated using computerized tomography images: the reference model, coracoid loop technique (CLT), and drilling technique (DT) model. In all these models, forces were applied to the clavicle along three axes (x, y, and z) of the trapezius and sternocleidomastoid muscles. Thereafter, data regarding the loading values of the tendon grafts, loads on the coracoid base, and coracoclavicular vertical distance were measured. RESULTS: While the reference model yielded the lowest values for all the loading conditions as well as the shortest coracoclavicular distance, the DT model demonstrated the highest values for all the loading conditions and the largest coracoclavicular distance. CONCLUSION: Different tendon grafting techniques may offer different loading values on both bone surface and tendon graft during coracoclavicular ligament reconstruction. The drilling technique may be associated with increased loading on the tendon graft and bone surface, causing further loss of reduction and consequent complications.

Biomechanical comparison of double versus triple button reconstruction techniques in patients with acromioclavicular joint dislocation.

BACKGROUND: Although many techniques are used to treat the acromioclavicular (AC) joint dislocations, minimal invasive or arthroscopic coracoclavicular ligament reconstructions became popular recently. In this study, authors compared the biomechanical results of double versus triple button reconstruction techniques. METHODS: Three-dimensional solid modeling of the shoulder girdle was carried out using virtual finite element modeling. AC joint dislocation was applied to the reference model, and these models were repaired by double and triple button techniques, respectively. Maximum equivalent stresses on buttons and sutures as well as displacements and reaction forces on AC joint were evaluated. RESULTS: Triple button model was more stable during flexion and abduction when compared with double button technique. CONCLUSION: Mimicking conoid ligament has a crucial mission more particularly against resistance during frontal plane actions, but the absence of the trapezoid ligament causes increasing the posterior displacement of the distal clavicle during the flexion of GH joint.

Hemodynamic effect of bypass geometry on intracranial aneurysm: A numerical investigation.

BACKGROUND AND OBJECTIVE: Hemodynamic analyzes are used in the clinical investigation and treatment of cardiovascular diseases. In the present study, the effect of bypass geometry on intracranial aneurysm hemodynamics was investigated numerically. Pressure, wall shear stress (WSS) and velocity distribution causing the aneurysm to grow and rupture were investigated and the best conditions were tried to be determined in case of bypassing between basilar (BA) and left/right posterior arteries (LPCA/RPCA) for different values of parameters. METHODS: The finite volume method was used for numerical solutions and calculations were performed with the ANSYS-Fluent software. The SIMPLE algorithm was used to solve the discretized conservation equations. Second Order Upwind method was preferred for finding intermediate point values in the computational domain. As the blood flow velocity changes with time, the blood viscosity value also changes. For this reason, the Carreu model was used in determining the viscosity depending on the velocity. RESULTS: Numerical study results showed that when bypassed, pressure and wall shear stresses reduced in the range of 40-70% in the aneurysm. Numerical results obtained are presented in graphs including the variation of pressure, wall shear stress and velocity streamlines in the aneurysm. CONCLUSION: Considering the numerical results for all parameter values, it is seen that the most important factors affecting the pressure and WSS values in bypassing are the bypass position on the basilar artery (Lb) and the diameter of the bypass vessel (d). Pressure and wall shear stress reduced in the range of 40-70% in the aneurysm in the case of bypass for all parameters. This demonstrates that pressure and WSS values can be greatly reduced in aneurysm treatment by bypassing in cases where clipping or coil embolization methods can not be applied.

Evaluation of the plate location used in clavicle fractures during shoulder abduction and flexion movements: a finite element analysis.

PURPOSE: Plate fixation is a commonly used surgical method in clavicular fracture treatment. The main purpose of this treatment is making the painless shoulder girdle and bring the functions to the optimum level. Plate fixation position still remains controversial. We aimed to investigate the effect of the plate position in clavicle midshaft fractures during shoulder movements. METHODS: A normal anatomical shoulder joint was modeled using computed tomography images. A fracture line was created on the clavicle. Plate was placed superior to the clavicle in group 1 and anterior in group 2. The impacts of joints, plates, screws, ligaments and clavicle have been shown during 150° flexion and abduction movements of the shoulder by finite element analysis. Analyzes were made non-linear using ANSYS (version 18) and the same boundary conditions were applied in all models. RESULTS: The load values in the plate, screws, ligaments, and clavicle were higher in group 1 than group 2 during abduction and flexion movements. Especially the load on the ac ligament was excessive. Load value in the glenohumeral joint was found similar both groups. The load values in the flexion movement were higher than the abduction movement in both groups. CONCLUSIONS: Anterior clavicle plating provides less stress on material and shoulder girdle, compared to superior plating, during shoulder abduction and flexion movements.

Comparison of reaction forces on the anterior cruciate and anterolateral ligaments during internal rotation and anterior drawer forces at different flexion angles of the knee joint.

BACKGROUND: Having a complicated anatomy, the knee joint has been further detailed and a new formation defined, the anterolateral ligament (ALL), in recent studies. While the importance of this ligament, which previously was associated with Segond fractures, was explained via clinical, radiologic and biomechanical studies, and basically, is thought to be a fixator structures for the tibia against internal rotation stress. Although in recent studies efficient surgical treatment was applied to patients who underwent anterior cruciate ligament (ACL) operation, some patients having a positive pivot test highlights the clinical importance of the ALL. The aim of this study is to evaluate reaction forces of different flexion angles on the tibia during internal rotation and anterior drawer tests on both the ALL and ACL, and to examine theimportance of this ligament in knee biomechanics by a finite element analysis method. METHOD: In this study, normal anatomy knee joint was modelled using Computed Tomography images from lower extremity length in DICOM format. 0°, 15°,30°,45°,60°,75° and 90° angles of flexion were applied, respectively, to these models and reaction force vectors formed on both ligaments were examined separately and as total vector and size by applying internal rotation and anterior drawer forces on each model. Non-linear analysis was conducted using ANSYS (version 17) with the same limit conditions applied to all models. RESULTS: After all models were examined, in general when comparing reaction forces, those on the ACL were found to be higher. However, when vectoral directions were examined, forces on ALL increased with increased flexion ratio and internal rotation momentum. Beyond 30° flexion, the tensile force on the ALL is increased and compressive overload on the ACL occurs. CONCLUSION: The ALL plays an important role in stability, especially against internal rotation forces, and an increased knee joint flexion ratio increases the stability contribution ratio. In particular, at 30° and higher angles, ACL reflects an antagonist effect and contributes to knee joint stability for rotational and mediolateral transposition.

The relationship between medial meniscal subluxation and stress distribution pattern of the knee joint: Finite element analysis.

BACKGROUND: Degenerative changes of the knee joint and clinical follow-up after meniscal subluxation are well documented. In the current study three-dimensional (3D) finite element analysis (FEA) of human lower limb was used to investigate the effect medial meniscal subluxation on the loadings of the knee structures. METHODS: Apart from the reference model, a total of ten 3D models were created, according to amount of medial meniscal subluxation. ANSYS® 14 was used to analyze the stress/load distribution, that is to say the maximum equivalent stress (MES) (von Mises stress) on bones, cartilages, ligaments and menisci. MES was expressed as Newton/mm(2) = Megapascal (MPa). RESULTS: In a static and standing upright position the MES on all knee structures were evaluated in the reference model. Although MES increased in all structures with the increase of medial meniscal subluxation degree, tibia cartilage was found to be the most affected structure with an increase of 22.73-fold in the 10 mm subluxation model when compared with references values. CONCLUSION: This study showed that medial meniscus subluxation is associated with increased loadings on all knee structures especially the tibia cartilage. Also the degree of the medial meniscal subluxation correlates with distribution and the amount of loadings on tibia cartilage which may be a prominent feature of knee osteoarthritis.

Changes in the loadings on the shoulder girdle in the case of scapulothoracic fusion.

BACKGROUND: Scapulothoracic fusion (STF) may be an alternative and salvage procedure in the treatment of scapular winging. The biomechanical effects of this procedure on the shoulder girdle have not been previously considered. The purpose of this study is to demonstrate the relationship between STF and the stress distribution pattern of the shoulder girdle. METHODS: Three-dimensional solid modeling of the shoulder girdle was carried out using virtual finite element modeling. STF was applied to the reference model obtained in a computer environment. Dynamic and nonlinear analysis was performed. RESULTS: Stress distributions in joints and ligaments were calculated. With respect to loading on the joints, maximum equivalent stresses increased on acromioclavicular (AC) and GH joints in the case of STF during abduction and flexion respectively. CONCLUSION: Results revealed that STF is a non-physiological, static procedure leading to load increase on GH and AC joint cartilages, which may be a cause of potential joint osteoarthritis. Copyright © 2015 John Wiley & Sons, Ltd.

Evaluation of contact characteristics of a patient-specific artificial dysplastic hip joint.

This study addresses the results of the experimental measurements for the contact surface areas and contact pressure distributions of a dysplastic hip joint. The hip joint consists of pelvis, proximal femur and artificial cartilages for both acetabulum and femoral head. The dysplastic hip joint is modeled in three dimensional (3D) form using the computerized tomography (CT) images obtained in vivo of an adult female patient. The modeled hip joint components are manufactured as a non-natural dysplastic hip joint using different materials and manufacturing processes. The dysplastic hip joint produced is subjected to compression forces experimentally to measure the contact surface area and contact pressure distributions between the femoral head and acetabulum using the pressure sensitive Fuji film. Different types of specific fixtures and molds are designed and manufactured to produce the dysplastic hip joint components and perform the experimental studies. The measured results using a non-natural dysplastic hip joint are compared with relevant results reported in current literature considering the peak and mean contact pressure values. Therefore, the obtained results showed that the non-natural dysplastic hip models can be generated and replaced to determine the contact characteristics for an elusive cadaveric model. In conclusion, the artificial models might be useful to understand the contact pressure distributions and potential changes in surface pressure contours and their effects on the stress distributions.

The effect of proximal tibial corrective osteotomy on menisci, tibia and tarsal bones: a finite element model study of tibia vara.

BACKGROUND: Proximal tibial open wedge osteotomy (PTO) is a corrective operation used in the surgery of lower extremities and is applied to patients with varus deformities for sufficient correction. The aim of the study was to evaluate whether the PTO can achieve decreased stress-bearing on the tibia and tarsal bones in addition to correcting the mechanical axis of the lower limb in patients with tibia vara. METHODS: Three-dimensional (3D) solid modelling of the lower extremity was carried out using computed tomography (CT) and magnetic resonance (MR)-containing images of all of the bony elements and non-bony structures. PTO was applied to the obtained deformed model in the computer environment and the correction was carried out. RESULTS: Stress distributions in menisci, tibia and tarsal bones were calculated. With respect to loading on the tarsal bones, the maximum equivalent stresses on all bones decreased except for the navicula in the PTO-simulated model in the current study. CONCLUSION: These results clearly indicate that PTO can achieve decreased stresses on the tarsal bones in patients with tibia vara.