Biomechanical evaluation of type p condylar head osteosynthesis using conventional small-fragment screws reinforced by a patient specific two-component plate

Abstract Background The aim of this study was to evaluate via finite element analysis (FEA) the biomechanical behavior of conventional small-fragment screws reinforced by a patient-specific plate in type p condylar head. Methods A finite element model of the mandible was created using Mimics 12.1 software. A type p condylar head fracture was simulated in the right condyle, and the left condyle was used as a control. Two patterns of fixation were investigated: conventional two-screw fixation and the same fixation system reinforced with a small, patient-specific plate. Surface models were imported into the software Ansys 5.7for further volume mesh generation. Results The highest stress gradients were observed in the cortical layer of the lateral fragment, located near the screw. The conventional fixation method resulted in equivalent stresses 2 to 10 times greater than the reinforced method. Rigidity of fixation in the reinforced method increased up to 1.25–3 times compared to the conventional two-screw technique. Conclusion This study’s findings suggest significant benefits in unfavorable biomechanical conditions from reinforcement of the standard two-screw fixation of condylar head fractures with a small, patient-specific plate acting as a washer.

Download Full-text

Biomechanical evaluation of type p condylar head osteosynthesis using conventional small-fragment screws reinforced by a patient specific two-component plate

10.21203/rs.3.rs-22506/v1 ◽

2020 ◽

Author(s):

Tetiana Pavlychuk ◽

Denis Chernogorskyi ◽

Yurii Chepurnyi ◽

Andreas Neff ◽

Andrii Kopchak

Keyword(s):

Finite Element ◽

Screw Fixation ◽

Cortical Layer ◽

Fixation Method ◽

Patient Specific ◽

Small Fragment ◽

Element Analysis ◽

Biomechanical Behavior ◽

Condylar Head ◽

Small Patient

Abstract Background. The aim of this study was to evaluate via finite element analysis (FEA) the biomechanical behavior of conventional small-fragment screws reinforced by a patient-specific plate in type p condylar head.Methods. A finite element model of the mandible was created using Mimics 12.1 software. A type p condylar head fracture was simulated in the right condyle, and the left condyle was used as a control. Two patterns of fixation were investigated: conventional two-screw fixation and the same fixation system reinforced with a small, patient-specific plate. Surface models were imported into the software Ansys 5.7 for further volume mesh generation.Results. The highest stress gradients were observed in the cortical layer of the lateral fragment, located near the screw. The conventional fixation method resulted in equivalent stresses 2 to 10 times greater than the reinforced method. Rigidity of fixation in the reinforced method increased up to 1.25–3 times compared to the conventional two-screw technique.Conclusion. This study’s findings suggest significant benefits in unfavourable biomechanical conditions from reinforcement of the standard two-screw fixation of condylar head fractures with a small, patient-specific plate acting as a washer.

Download Full-text

The Patient-Specific Brace Design and Biomechanical Analysis of Adolescent Idiopathic Scoliosis

Journal of Biomechanical Engineering ◽

10.1115/1.3049843 ◽

2009 ◽

Vol 131 (4) ◽

Cited By ~ 17

Author(s):

Wen-Zhong Nie ◽

Ming Ye ◽

Zu-De Liu ◽

Cheng-Tao Wang

Keyword(s):

Finite Element ◽

Measurement System ◽

Element Model ◽

Biomechanical Study ◽

Biomechanical Analysis ◽

Patient Specific ◽

Sacral Slope ◽

Element Analysis ◽

Biomechanical Behavior ◽

Idiopathic Adolescent Scoliosis

Brace application has been reported to be an effective approach in treating mild to moderate idiopathic adolescent scoliosis. However, little attention is focused on the biomechanical study of patient-specific brace treatment. The purpose of this study was to propose a design method of personalized brace and to analyze its biomechanical behavior and to compare the brace forces with the I-Scan measurement system. Based on a three-dimensional patient-specific finite element model of the spine, rib cage, pelvis, and abdomen, a parametric patient-specific model of a thoracolumbosacral orthosis was built. The interaction between the torso and the brace was modeled by surface-to-surface contact interface. Three standard strap tensions (20 N, 40 N, and 60 N) were loaded on the back of the brace to simulate the strap tension. The I-Scan distribution pressure measurement system was used to measure the different region pressures, and the equivalent forces in these regions were calculated. The spinal curve changes and the forces acted on the brace generated by the strap tension were evaluated and compared with the measurement. The reduction in the coronal curvature was about 60% for a strap tension of 60 N. The sacral slope and the lordosis were partially reduced in this case, but the kyphosis had no obvious change. The brace slightly modified the axial rotation at the apex of the scoliotic curve. The forces generated in finite element analysis were approximately in good agreement with the measurement. The design and biomechanical analysis methods of patient-specific brace should be useful in the design of more effective braces.

Download Full-text

Biomechanical Evaluation of a Carbon Fibre Epoxy Composite Plate in an Injured and Healed Femur Using Infrared Thermography and Finite Element Analysis

10.32920/ryerson.14660766 ◽

2021 ◽

Author(s):

Faisal Sharaf Siddiqui

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Carbon Fibre ◽

Fracture Fixation ◽

High Energy ◽

Metal Plate ◽

Fixation Method ◽

Element Analysis ◽

Femur Fractures ◽

Biomechanical Behavior

Femur fractures are caused by high energy trauma or by musculoskeletal impairments, such as osteoporosis. The presence of total hip replacement (THR) superior to a femoral mid-shaft fracture greatly complicates fixation and treatment. The most conventional fracture fixation method is internal fixation by metal plate and screws. However, metal being stiffer than bone, causes stress shielding and bone resorption. The goal of this study was to evaluate the performance of a less stiff carbon fibre epoxy plate as fracture fixation in an injured and healed femur. IR thermography validated by finite element analysis (FEA) was used to investigate the stress patterns of an injured and healed femur under an average cyclic loading of 800 N at an adduction angle of 7 degrees to simulate the single-legged stance phase of walking. The average stiffness of an injured femur with carbon/epoxy plate was 532.1 N/mm (static) and 625.3 N/mm (dynamic) respectively, that increased to 597.6 N/mm (static) and 697.9 N/mm (dynamic) for the metal plate. For the healed femur, the average stiffness increased from 1660.3 N/mm (static) and 2010.0 N/mm (dynamic) for the carbon/epoxy plate to 1704.4 N/mm (static) and 2070.4 N/mm (dynamic) for the metal plate. IR stress maps for carbon/epoxy and metal plate (injured femur) showed an overall difference of 29.2% for the anterior and posterior sides. This is the first study to assess experimentally and computationally the biomechanical behavior of injured and healed synthetic femur with two different plates construct.

Download Full-text

Use of transilial pinning for the treatment of sacroiliac separation in 25 dogs and finite element analysis of repair methods

Veterinary and Comparative Orthopaedics and Traumatology ◽

10.1055/s-0037-1616586 ◽

2007 ◽

Vol 20 (01) ◽

pp. 38-42 ◽

Cited By ~ 5

Author(s):

D. Comiskey ◽

B. MacDonald ◽

W. T. McCartney

Keyword(s):

Finite Element ◽

Surgical Intervention ◽

Screw Fixation ◽

Weight Bearing ◽

Fixation Method ◽

Element Analysis ◽

Free Weight ◽

Micro Motion ◽

And Migration ◽

Minor Injuries

SummaryA retrospective study of 25 cases of sacroiliac separation showed that transilial pinning is an effective method of repair for sacroiliac separations. Only 8% of cases of sacroiliac separation had transilial pinning as the sole surgical intervention as other concomitant minor injuries, such as fractured ischium or pubis, did not require surgery. Even though pin loosening and migration along with local soft tissue irritation occurred in all cases, 92% of the cases had ‘good’ or ‘excellent’ outcomes. Sacroiliac separation heals by fibrosis, not directly by bone healing, and therefore can heal sufficiently in four weeks to allow pain free weight bearing in four weeks. Additionally, finite element modelling was undertaken to analyse micro-movement of repaired sacroiliac separations. The micro-motion analysis showed that the lag screw fixation method was more stable than the transilial fixation method since the relative motion between the two indicated that the latter allowed more unsupported iliac movement.

Download Full-text

Biomechanical Assessment of Vertebroplasty Combined with Cement-Augmented Screw Fixation for Lumbar Burst Fractures: A Finite Element Analysis

Applied Sciences ◽

10.3390/app10062133 ◽

2020 ◽

Vol 10 (6) ◽

pp. 2133 ◽

Cited By ~ 2

Author(s):

Yueh-Ying Hsieh ◽

Yi-Jie Kuo ◽

Chia-Hsien Chen ◽

Lien-Chen Wu ◽

Chang-Jung Chiang ◽

...

Keyword(s):

Finite Element ◽

Screw Fixation ◽

Burst Fracture ◽

Fixation Method ◽

Finite Element Models ◽

Lateral Bending ◽

Hybrid Fixation ◽

Element Analysis ◽

Biomechanical Assessment ◽

Burst Fractures

A hybrid fixation method, using a combination of vertebroplasty and cement-augmented screws, has been demonstrated as a useful technique for securing osteoporotic burst fractures. The purpose of this study was to assess changes in the range of motion (ROM) and stress in the spine after treating a lumbar burst fracture with this hybrid method. Five finite element models were developed: (a) intact lumbar spine (INT), (b) INT with vertebroplasty at L3 (AwC), (c) two-segment fixation of AwC (AwC-TSF), (d) AwC-TSF model with cement-augmented screws (AwC-TSF-S), and (e) INT with an L3 burst fracture treated with two-segment fixation (TSF). After loading, the models were evaluated in terms of the ROM of each motion segment, stiffness of fusion segments, and stresses on the endplates and screws. The results showed that the TSF model has a larger ROM at the instrumented segments than both the AwC-TSF and AwC-TSF-S models. The stiffness at L2–L4 under extension and lateral bending in AwC-TSF, AwC-TSF-S and TSF was approximately nine times greater than the INT model. In conclusion, the hybrid fixation method (AwC-TSF-S) results in a stiffer construct and lower ROM at instrumented segments, which may also reduce the risk of fracture of adjacent vertebrae.

Download Full-text

Biomechanical Evaluation of a Carbon Fibre Epoxy Composite Plate in an Injured and Healed Femur Using Infrared Thermography and Finite Element Analysis

10.32920/ryerson.14660766.v1 ◽

2021 ◽

Author(s):

Faisal Sharaf Siddiqui

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Carbon Fibre ◽

Fracture Fixation ◽

High Energy ◽

Metal Plate ◽

Fixation Method ◽

Element Analysis ◽

Femur Fractures ◽

Biomechanical Behavior

Femur fractures are caused by high energy trauma or by musculoskeletal impairments, such as osteoporosis. The presence of total hip replacement (THR) superior to a femoral mid-shaft fracture greatly complicates fixation and treatment. The most conventional fracture fixation method is internal fixation by metal plate and screws. However, metal being stiffer than bone, causes stress shielding and bone resorption. The goal of this study was to evaluate the performance of a less stiff carbon fibre epoxy plate as fracture fixation in an injured and healed femur. IR thermography validated by finite element analysis (FEA) was used to investigate the stress patterns of an injured and healed femur under an average cyclic loading of 800 N at an adduction angle of 7 degrees to simulate the single-legged stance phase of walking. The average stiffness of an injured femur with carbon/epoxy plate was 532.1 N/mm (static) and 625.3 N/mm (dynamic) respectively, that increased to 597.6 N/mm (static) and 697.9 N/mm (dynamic) for the metal plate. For the healed femur, the average stiffness increased from 1660.3 N/mm (static) and 2010.0 N/mm (dynamic) for the carbon/epoxy plate to 1704.4 N/mm (static) and 2070.4 N/mm (dynamic) for the metal plate. IR stress maps for carbon/epoxy and metal plate (injured femur) showed an overall difference of 29.2% for the anterior and posterior sides. This is the first study to assess experimentally and computationally the biomechanical behavior of injured and healed synthetic femur with two different plates construct.

Download Full-text