This article aims to compare and analyze the biomechanical differences between wing-shaped titanium plates and traditional titanium plates in fixing acetabular anterior column and posterior hemi-transverse (ACPHT) fracture under multiple working conditions using the finite element method. Firstly, four sets of internal fixation models for acetabular ACPHT fractures were established, and the hip joint stress under standing, sitting, forward extension, and abduction conditions was calculated through analysis software. Then, the stress of screws and titanium plates, as well as the stress and displacement of the fracture end face, were analyzed. Research has found that when using wing-shaped titanium plates to fix acetabular ACPHT fractures, the peak stress of screws decreases under all working conditions, while the peak stress of wing-shaped titanium plates decreases under standing and sitting conditions and increases under forward and outward extension conditions. The relative displacement and mean stress of the fracture end face decrease under all working conditions, but the values are higher under forward and outward extension conditions. Wing-shaped titanium plates can reduce the probability of screw fatigue failure when fixing acetabular ACPHT fractures and can bear greater loads under forward and outward extension conditions, improving the mechanical stability of the pelvis. Moreover, the stress on the fracture end surface is more conducive to stimulating fracture healing and promoting bone tissue growth. However, premature forward and outward extension rehabilitation exercises should not be performed.
Titanium ; Bone Plates ; Humans ; Acetabulum/surgery* ; Fracture Fixation, Internal/methods* ; Biomechanical Phenomena ; Finite Element Analysis ; Bone Screws ; Fractures, Bone/surgery* ; Stress, Mechanical ; Working Conditions

OBJECTIVE: To compare the biomechanical properties of personalized Y-shaped plates with horizontal plates, vertical plates, and traditional Y-shaped plates in the treatment of distal humeral intra-articular fractures through finite element analysis, and to evaluate their potential for clinical application. METHODS: The study selected a 38-year-old male volunteer and obtained a three-dimensional model of the humerus by scanning his upper limbs using a 64-slice spiral CT. Four types of fracture-internal fixation models were constructed using Mimics 19.0, Geomagic Wrap 2017, Creo 6.0, and other software: horizontal plates, vertical plates, traditional Y-shaped plate, and personalized Y-shaped plate. The models were then meshed using Hypermesh 14.0 software, and material properties and boundary conditions were defined in Abaqus 6.14 software. AnyBody 7.3 software was used to simulate elbow flexion and extension movements, calculate muscle strength, joint forces, and load torques, and compare the peak stress and maximum displacement of the four fixation methods at different motion angles (10°, 30°, 50°, 70°, 90°, 110°, 130°, 150°) during elbow flexion and extension. RESULTS: Under dynamic loading during elbow flexion and extension, the personalized Y-shaped plate exhibits significant biomechanical advantages. During elbow flexion, the peak internal fixation stress of the personalized Y-shaped plate was (28.8±0.9) MPa, which was significantly lower than that of the horizontal plates, vertical plates, and traditional Y-shaped plate ( P<0.05). During elbow extension, the peak internal fixation stress of the personalized Y-shaped plate was (18.1±1.6) MPa, which was lower than those of the other three models, with significant differences when compared with horizontal plates and vertical plates ( P<0.05). Regarding the peak humeral stress, the personalized Y-shaped plate model showed mean values of (10.9±0.8) and (13.1±1.4) MPa during elbow flexion and extension, respectively, which were significantly lower than those of the other three models ( P<0.05). Displacement analysis showed that the maximum displacement of the humerus with the personalized Y-shaped plate during elbow flexion was (2.03±0.08) mm, slightly higher than that of the horizontal plates, but significantly lower than that of the vertical plates, showing significant differences ( P<0.05). During elbow extension, the maximum displacement of the humerus with the personalized Y-shaped plate was (1.93±0.13) mm, which was lower than that of the other three models, with significant differences when compared with vertical plates and traditional Y-shaped plates ( P<0.05). Stress contour analysis showed that the stress of the personalized Y-shaped plate was primarily concentrated at the bifurcation of the Y-shaped structure. Displacement contour analysis showed that the personalized Y-shaped plate effectively controlled the displacement of the distal humerus during both flexion and extension, demonstrating excellent stability. CONCLUSION The personalized Y-shaped plate demonstrates excellent biomechanical performance in the treatment of distal humeral intra-articular fractures, with lower stress and displacement, providing more stable fixation effects.
Humans ; Male ; Adult ; Healthy Volunteers ; Finite Element Analysis ; Tomography, Spiral Computed ; Models, Anatomic ; Biomechanical Phenomena ; Humeral Fractures, Distal/surgery* ; Fracture Fixation, Internal/instrumentation* ; Bone Plates ; Computer Simulation ; Precision Medicine/methods* ; Elbow Joint/surgery* ; Elbow/surgery* ; Humerus/surgery* ; Torque ; Stress, Mechanical ; Intra-Articular Fractures/surgery* ; Prosthesis Design/methods* ; Imaging, Three-Dimensional ; Range of Motion, Articular

OBJECTIVE: To investigate whether adding 1 transverse screw (TS) to the triangular parallel cannulated screw (TPCS) fixation has a mechanical stability advantage for Pauwels type Ⅲ femoral neck fractures by conducting finite element analysis on four internal fixation methods. METHODS: Based on CT data of a healthy adult male volunteer's femur, three Pauwels type Ⅲ femoral neck fracture models (Pauwels angle 70°, Pauwels angle 80°, and Pauwels angle 70° combined with bone defect) were constructed using Mimics 21.0 software and SolidWorks 2017 software. Four different internal fixation models were built at the same time, including TPCS, TPCS+TS, three cross screws (TCS), and TPCS+medial buttress plate (MBP). The mechanical stability of different models under the same load was compared by finite element analysis. RESULTS: The femoral model established in this study exhibited a maximum stress of 28.62 MPa, with relatively higher stress concentrated in the femoral neck. These findings were comparable to previous studies, indicating that the constructed femoral finite element model was correct. The maximum stress of internal fixation in finite element analysis showed that TCS was the lowest and TPCS+MBP was the highest in Pauwels angle 70° and 80° models, while TPCS+TS was the lowest and TCS was the highest in Pauwels angle 70° combined with bone defect model. The maximum displacement of internal fixation in each fracture model was located at the top of the femoral head, with TCS having the highest maximum displacement of the femur. The maximum stress of fracture surface in finite element analysis showed that TCS was the lowest and TPCS was the highest in the Pauwels angle 70° model, while TPCS+MBP was the lowest and TPCS/TCS were the highest in the Pauwels angle 80° model and the Pauwels angle 70° combined with bone defect model, respectively. The maximum displacement of fracture surfece analysis showed that TPCS+MBP was the lowest and TCS was the highest in Pauwels angle 70° and 80° models, while TPCS+TS was the lowest and TCS was the highest in Pauwels angle 70° combined with bone defect model. CONCLUSION For Pauwels type Ⅲ femoral neck fractures, the biomechanical stability of TPCS+TS was superior to that of TPCS alone and TCS, but it has not yet reached the level of TPCS+MBP.
Finite Element Analysis ; Humans ; Femoral Neck Fractures/diagnostic imaging* ; Bone Screws ; Fracture Fixation, Internal/instrumentation* ; Male ; Bone Plates ; Stress, Mechanical ; Biomechanical Phenomena ; Tomography, X-Ray Computed ; Adult ; Femur Neck/surgery*

OBJECTIVE: To investigate the effects of bone density, plate bending degree and proximal screw type on the stress fracture of clavicle hook. METHODS: Three sows weighing between 45 and 50 kg were selected, from which a total of 40 rivs were collected. The 15 ribs of sows were divided into 3 groups according to bone density and bone hardness with 5 rivs in each group. And then the 3 groups were fixed with 6-hole collarbone hook plates and 3 locking screws. Measure the maximum torsion force when the ribs were fractured by force. The same size 15 rids were divided into 3 groups, named forward bending group, 0° group(the angle between the plate surface and the rib surface) and reverse bending group. All fixed with 6-hole collarbone hook plates and locking screws to measure the maximum torsion force of rib stress fracture. Then the same size 10 rids were divided into 2 groups, the normal screw group and the locking screw group with 5 ribs in each group. Both groups were fixed with 6-hole collarbone hook plates and screws. The normal screw group was a normal screw, fixed in proximal end, and two locking screws. The locking screw group was fixed by locking screws. Measure the maximum torsion force of the two groups when the ribs fracture by force. RESULTS: In the bone density experiment, the torque force of hard bone group (104.51±6.27) N was greater than the normal bone group (75.04±3.81) N(t=8.979, P<0.05). The force of normal bone group was greater than the osteoporosis group (49.99±2.12) N(t=12.832, P<0.05). In the bending collarbone hook experiment, the order of the torque force generated by each group as follow:the forward bending group (343.59±6.18) N greater than the 0° group (106.01±5.29) N(t=65.279, P<0.05) greater than the reverse bending group (95.82±4.12) N(t=3.398, P<0.05). The force of the normal screw group (98.68±0.70) N was greater than the locking screw group (50.20±0.95) N(t=91.484, P<0.05). The data comparisons of each group were statistically significant. CONCLUSION Bone density, plate bending degree and proximal screw type had an impact on stress fracture of clavicle hook plate. Higher bone density, forward bending of the steel plate, and ordinary screws in proximal end can reduce the rates of stress fractures of clavicle hooks.
Animals ; Bone Plates ; Clavicle/surgery* ; Swine ; Fractures, Stress/etiology* ; Female ; Risk Factors ; Fracture Fixation, Internal/instrumentation* ; Bone Screws ; Biomechanical Phenomena ; Bone Density

OBJECTIVES: This study aims to analyze the biomechanics of three kinds of rigid internal fixation methods for condylar head fractures. METHODS: A three dimensional finite element model of the normal mandible was constructed. It was then used to prepare condylar head fracture finite element model and three kinds of rigid internal fixation finite element model (unilateral tension screw, bilateral tension screw, tension screw+titanium plate). The mechanical characteristics and changes of the mandible condyle under the same mechanical conditions were compared among the three different rigid internal fixation methods. RESULTS: The maximum equivalent stress and displacement of the non-free end of condyle under the rigid internal fixation method of unilateral tension screw were 71.03 MPa and 4.72 mm, respectively. The maximum equivalent stress and displacement of the free end of condyle were 78.45 MPa and 4.50 mm, respectively. The maximum stress of fracture suture was 3.27 MPa. The maximum equivalent stress and displacement of the non-free end of condyle under the rigid internal fixation method of bilateral tension screw were 70.52 MPa and 4.00 mm, respectively. The maximum equivalent stress and displacement of the free end of condyle were 72.49 MPa and 3.85 mm, respectively. The maximum stress of fracture suture was 2.33 MPa. The maximum equivalent stress and maximum displacement of the non-free end of condyle under the rigid internal fixation method of tension screw+titanium plate were 67.26 MPa and 2.66 mm, respectively. The maximum equivalent stress and maximum displacement of the free end of condyle were 69.66 MPa and 2.50 mm, respectively. The maximum stress of fracture suture was 2.18 MPa. CONCLUSIONS The tension screw+titanium plate rigid internal fixation method is the most conducive to biomechanical distribution for condylar head fractures.
Fracture Fixation, Internal/instrumentation* ; Mandibular Condyle/surgery* ; Biomechanical Phenomena ; Bone Screws ; Finite Element Analysis ; Humans ; Mandibular Fractures/surgery* ; Bone Plates ; Titanium ; Stress, Mechanical

PURPOSE: The treatment and outcome of tibial stress fractures concomitant with knee osteoarthritis (OA) are complicated. The aim of this study was to evaluate the functional and radiological outcome of total knee arthroplasty with long tibial stem as a treatment for patients having knee OA and tibial stress fracture. METHODS: Patients who were diagnosed to have proximal tibia stress fracture along with knee OA at our institution between June 2013 and November 2018 were included in our study. All patients underwent total knee arthroplasty with long tibial stem. Preoperative and postoperative functional assessments were done according to range of movement of the knee joint, knee society score and knee injury and OA outcome score. Descriptive analysis was carried out by mean and standard deviation for quantitative variables, frequency and proportion for categorical variables. RESULTS: Twelve patients were included in the study. All patients were found to have stress fractures in the proximal half of tibia and extra-arthrosis. Four patients had non-union/delayed union, and 8 patients had acute fractures. The average preoperative range of movement was 88.1°, which improved to 116.3° at 3 months following surgery. It was found that the fracture has healed in all cases. Mean knee society score improved from 32.9 preoperatively to 89.3 at 1 year follow-up. Knee injury and OA outcome score improved from a mean score of 28.3 preoperatively to 81.1 at 1 year follow-up. CONCLUSION Stress fractures can occur in the proximal tibia in patients with knee OA. Total knee arthroplasty with tibial stem provides a suitable solution for both conditions. Additional plating or bone graft is unlikely to be required.
Humans ; Arthroplasty, Replacement, Knee/adverse effects* ; Osteoarthritis, Knee/surgery* ; Tibia/surgery* ; Fractures, Stress/surgery* ; Tibial Fractures ; Knee Joint ; Knee Injuries/surgery* ; Treatment Outcome

OBJECTIVE: To analyze the biomechanical mechanism of mandibular symphyseal fracture combined with bilateral intracapsular condylar fractures using finite element analysis (FEA). METHODS: Maxillofacial CT scans and temporomandibular joint (TMJ) MRI were performed on a young male with normal mandible, no wisdom teeth and no history of TMJ diseases. The three-dimensional finite element model of mandible was established by Mimics and ANSYS based on the CT and MRI data. The stress distributions of mandible with different angles of traumatic loads applied on the symphyseal region were analyzed. Besides, two models with or without disc, two working conditions in occlusal or non-occlusal status were established, respectively, and the differences of stress distribution between them were compared. RESULTS: A three-dimensional finite element model of mandible including TMJ was established successfully with the geometry and mechanical properties to reproduce a normal mandibular structure. Following a blow to the mandibular symphysis with different angles, stress concentration areas were mainly located at condyle, anterior border of ramus and symphyseal region under all conditions. The maximum equivalent stress always appeared on condylar articular surface. As the angle between the external force and the horizontal plane gradually increased from 0° to 60°, the stress on the mandible gradually concentrated to symphysis and bilateral condyle. However, when the angle between the external force and the horizontal plane exceeded 60°, the stress tended to disperse to other parts of the mandible. Compared with the condition without simulating the disc, the stress distribution of articular surface and condylar neck decreased significantly when the disc was present. Compared with non-occlusal status, the stress on the mandible in occlusal status mainly distributed on the occlusal surface, and no stress concentration was found in other parts of the mandible. CONCLUSION When the direction of external force is 60° from the horizontal plane, the stress distribution mainly concentrates on symphyseal region and bilateral condylar surface, which explains the occurrence of symphyseal fracture and intracapsular condylar fracture. The stress distribution of condyle (including articular surface and condylar neck) decreases significantly in the presence of arti-cular disc and in stable occlusal status when mandibular symphysis is under traumatic force.
Finite Element Analysis ; Humans ; Male ; Mandible ; Mandibular Condyle/diagnostic imaging* ; Mandibular Fractures/diagnostic imaging* ; Stress, Mechanical ; Temporomandibular Joint/diagnostic imaging* ; Temporomandibular Joint Disorders

Fracture is a common physical injury. Its healing process involves complex biological activities at tissue, cellular and molecular levels and is affected by mechanical and biological factors. Over recent years, numerical simulation methods have been widely used to explore the mechanisms of fracture healing, design fixators and develop novel treatment strategies, etc. This paper mainly recommend the numerical methods used for simulating fracture healing and their latest research progress, which helps people better understand the mechanism of fracture healing, and also provides direction and guidance for the numerical simulation research of fracture healing in the future. First, the fracture healing process and its relationship with mechanical stimulation and biological factors are described. Then, the numerical models used for simulating fracture healing (including mechano-regulatory model, biological regulatory model and mechano-biological regulatory model) and corresponding modeling techniques (mainly including agent-based techniques and fuzzy logic controlling method) were summarized in particular. Finally, the future research directions in numerical simulation of fracture healing were preliminarily prospected.
Computer Simulation ; Fracture Healing ; Fractures, Bone ; Humans ; Models, Biological ; Stress, Mechanical

A bone stress injury (BSI) means that the bones cannot tolerate repeated mechanical loads, resulting in structural fatigue and local bone pain. A delay in BSI diagnosis can lead to more serious injuries, such as stress fractures that require longer treatment periods. Therefore, early detection of BSI is an essential part of management. Risk factors for BSI development include biological and biomechanical factors. Medical history and physical examination are the basics for a BSI diagnosis, and magnetic resonance imaging is helpful for confirming and grading. In this paper, the authors review the overall content of BSI and stress fractures which are common in runners. Through this review, we hope that interest in stress fractures will be raised in Korea and that active researches will be conducted.
Diagnosis ; Fatigue ; Fractures, Stress ; Hope ; Korea ; Magnetic Resonance Imaging ; Physical Examination ; Risk Factors

Atypical fractures associated with prolonged bisphosphonate (BP) therapy rarely occur outside the femur, and the diagnostic criteria, appropriate treatment principles, and fixation methods for atypical ulnar fractures have not been established. The authors experienced the use of internal fixation with a metal plate and a new internal fixation method with an intramedullary nail in the treatment of an atypical ulnar fracture in a patient who had been on BP therapy for 10 to 20 years. This paper reports findings along with a review of the relevant literature.
Femur ; Fractures, Stress ; Humans ; Methods ; Osteoporosis ; Ulna