Biomechanical evaluation of different internal fixation methods based on finite element analysis for Pauwels type III femoral neck fracture

Jiang, Xianbao; Liang, Ke; Du, Gang; Chen, Yuan; Tao, Yu; Geng, Kuihua

doi:10.1016/j.injury.2022.08.038

Cited by 23 publications

(6 citation statements)

References 29 publications

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“…FNS incorporates numerous advantages, including offering excellent angular stability, minimizing vascular damage, dynamic compression, and anti-rotation. At present, there have been numerous finite element analysis experiments [ 14 , 19 , 20 ] studying the immediate stability of FNS and CSS in treating femoral neck fractures. However, there is scarce mechanical analysis available regarding the effects post internal fixation removal.…”

Section: Discussionmentioning

confidence: 99%

“…The conditions set for single-leg standing involved a force exerted on the hip joint that was roughly equivalent to threefold the individual’s body mass, which translates to a measurement of 1800 N [ 12 ]. The stress on the proximal femur was simplified, considering both the direction of force and muscle modeling [ 13 , 14 ]. Finally, in the condition for single-leg standing, deformation and equivalent stress of the model were observed.…”

Section: Methodsmentioning

confidence: 99%

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Biomechanical changes in the proximal femur before and after removal of femoral neck system

Nan,

Liu,

Zhang

et al. 2024

J Orthop Surg Res

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Background As an innovative internal fixation system, FNS (femoral neck system) is increasingly being utilized by surgeons for the treatment of femoral neck fractures. At present, there have been numerous finite element analysis experiments studying the immediate stability of FNS and CSS in treating femoral neck fractures. However, there is scarce mechanical analysis available regarding the effects post internal fixation removal. This study aimed to investigate the alterations in mechanical parameters of the proximal femur before and after the removal of FNS (femoral neck system), and to assess potential distinctions in indicators following the extraction of CSS (Cannulated Screws). Methods A proximal femur model was reconstructed using finite element numerical techniques. The models for CSS and FNS were formulated utilizing characteristics and parametric definitions. The internal fixation was combined with a normal proximal femur model to simulate the healing state after fracture surgery. Within the framework of static analysis, consistent stress burdens were applied across the entirety of the models. The total deformation and equivalent stress of the proximal femur were recorded before and after the removal of internal fixation. Results Under the standing condition, the total deformation of the model before and after removing CSS was 0.99 mm and 1.10 mm, respectively, indicating an increase of 12%. The total deformation of the model before and after removing FNS was 0.65 mm and 0.76 mm, respectively, indicating an increase of 17%. The equivalent stress for CSS and FNS were 55.21 MPa and 250.67 MPa, respectively. The average equivalent stress on the cross-section of the femoral neck before and after removal of CSS was 7.76 MPa and 6.11 MPa, respectively. The average equivalent stress on the cross-section of the femoral neck before and after removal of FNS was 9.89 MPa and 8.79 MPa, respectively. Conclusions The retention of internal fixation may contribute to improved stability of the proximal femur. However, there still existed risks of stress concentration in internal fixation and stress shielding in the proximal femur. Compared to CSS, the removal of FNS results in larger bone tunnels and insufficient model stability. Further clinical interventions are recommended to address this issue.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Biomechanical changes in the proximal femur before and after removal of femoral neck system

Nan,

Liu,

Zhang

et al. 2024

J Orthop Surg Res

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“…This indicates that the most medial screws have a significant impact on the overall pelvic stability and fixation strength after PAO. Therefore, surgeons should carefully consider how to ensure better accurate implantation ( Jiang et al, 2022 ). Furthermore, the failure analysis demonstrated that two-screw internal fixation techniques could provide sufficient capacity for the strain resistance to failure during the early PAO postoperative gait even in high-stress phases, although the TS group showed higher yield load, which is well higher than the gait load.…”

Section: Discussionmentioning

confidence: 99%

Mechanical upside of PAO mainstream fixations: co-simulation based on early postoperative gait characteristics of DDH patients

Yang

Liu

Lin³

et al. 2023

Front. Bioeng. Biotechnol.

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Purpose: To investigate the early postoperative gait characteristics of patients who underwent periacetabular osteotomy (PAO) and predict the biomechanical performance of two commonly used PAO fixation methods: iliac screw (IS) and transverse screw (TS).Methods: A total of 12 patients with unilateral developmental dysplasia of the hip (DDH) (mean age 27.81 ± 4.64 years, 42% male) that were scheduled to undergo PAO surgery were included in this study. Their preoperative CT images and pre- and postoperative gait data were used to create subject-specific musculoskeletal models and complete the inverse dynamics analysis (IDA). Two patients with typical gait characteristics were selected using clustering analysis, and their IDA data were incorporated into finite element (FE) models of IS and TS fixations. Failure simulation was performed by applying iterative steps with increasing gait load to predict yield load. Stress results and yield loads were calculated for each FE model at different phases of the gait cycle.Results: Postoperative gait showed improvement compared to preoperative gait but remained inferior to that of healthy individuals. Postoperative gait was characterized by a lower hip range of motion, lower peri-ilium muscle forces, particularly in the abductors, and a sharper initial peak and flatter second peak of hip joint reaction force (HRF). Finite element analysis (FEA) showed a trend of increasing stress during the second–fourth phases of the gait cycle, with lower stress levels in other phases. At high-stress gait phases, the mean stress of maximum p¯100 differed significantly between IS and TS (p < 0.05) and between coupled and uncoupled muscle forces (p < 0.05). Failure analysis predicted a slightly larger yield load for TS configurations (6.21*BW) than that for IS (6.16*BW), but both were well above the gait load. Coupled and uncoupled groups showed similar results, but uncoupled groups had lower yield loads (5.9*BW).Conclusion: PAO early postoperative gait shows a normalized trend, but abnormalities persist. IS and TS are both capable of resisting mechanical strain failure, with no significant mechanical advantage found for transverse screw fixation during PAO early postoperative gait. Additionally, it is important to note that the TS may have a higher risk of cyclic fatigue failure due to the localized greater stress concentration. Furthermore, the most medial screw is crucial for pelvic stability.

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“…The static hip contact loads in normal walking and climbing cycle gaits were set as follows as to a person weighing 70 kg (Heller et al, 2005;Taheri et al, 2011;Ramos et al, 2016;Cun et al, 2020): the hip joint contact load in the walking gait [(x,y,z) = (647, 236, −1,351)] and in the climbing gait [(x,y,z) = (711, 436, −1,393)], which were 2 times and 2.1 times body weight, respectively. Meanwhile, the dynamic hip contact loads in the two cycle gaits were adopted with curves, as shown in Figure 3 (Chalernpon et al, 2015;Zeng et al, 2020;Jiang et al, 2022).…”

Section: Friction Loading and Boundary Conditionsmentioning

confidence: 99%

Relative instability ratios of bone wall defects in trochanteric hip fractures: A finite element analysis

Yang

Mao

Chang

et al. 2023

Front. Bioeng. Biotechnol.

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Background: For decades, medial and lateral wall fragments of trochanteric hip fractures were considered two pivotal factors that could influence the stability of postoperative femur-implant complex. However, most studies seemed to misunderstand the concept of the posteromedial fragment and equated it with the medial wall, which overlooked vital roles of the anteromedial wall. Roles of the posterior coronal bone fragment were also highlighted in some research. However, influences of the bone walls above the trochanteric fracture instability are yet to be investigated and quantified by means of finite element analysis.Methods: Eight trochanteric fracture fixation models with different wall defects were constructed. Outcome indicators were the von Mises stress of the implant models, the maximum/minimum principal strain, the risky tensile/compressive volume and the volume ratios of the bone models, the femoral head vertex displacement, and the fracture surface gap. Based on these indicator values, the relative instability ratios were computed.Results: Outcome indicators, absolute values, and nephograms of all models showed the same upward and concentrating trends with exerted hip contact loads shifting from static walking to dynamic climbing. Similarly, these indicators also exhibited the same trends when the eight models were solved in sequence. Moreover, the relative instability ratio of the medial wall (100%), particularly the anteromedial part (78.7%), was higher than the figure for the lateral wall (36.6%).Conclusion: The anteromedial wall played relatively pivotal stabilizing roles in trochanteric hip fractures compared with the posteromedial wall and the lateral wall, which indicated that orthopedic surgeons should attach more importance to the anteromedial cortex support in an operating theatre.

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Biomechanical evaluation of different internal fixation methods based on finite element analysis for Pauwels type III femoral neck fracture

Cited by 23 publications

References 29 publications

Biomechanical changes in the proximal femur before and after removal of femoral neck system

Biomechanical changes in the proximal femur before and after removal of femoral neck system

Mechanical upside of PAO mainstream fixations: co-simulation based on early postoperative gait characteristics of DDH patients

Relative instability ratios of bone wall defects in trochanteric hip fractures: A finite element analysis

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