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Item type:Publication, Access status: with files , Biomechanical analysis of fixation methods in acetabular fractures : a systematic review of test setupsPurpose: Optimal anatomical reduction and stable fixation of acetabular fractures are important in avoiding secondary dislocation and osteoarthritis. Biomechanical studies of treatment options of acetabular fractures aim to evaluate the biomechanical properties of different fixation methods. As the setup of the biomechanical test can influence the experimental results, this review aimed to analyze the characteristics, comparability and clinical implications of studies on biomechanical test setups and finite element analyses in the fixation of acetabular fractures. Methods: A systematic literature research was conducted according to the PRISMA guidelines, using the PubMed/MEDLINE and Web of Science databases. 44 studies conducting biomechanical analyses of fixation of acetabular fractures were identified, which met the predefined inclusion and exclusion criteria and which were published in English between 2000 and April 16, 2021. The studies were analyzed with respect to distinct parameters, including fracture type, material of pelvis model, investigated fixation construct, loading direction, loading protocol, maximum loading force, outcome parameter and measurement method. Results: In summary, there was no standardized test setup within the studies on fixation constructs for acetabular fractures. It is therefore difficult to compare the studies directly, as they employ a variety of different test parameters. Furthermore, the clinical implications of the biomechanical studies should be scrutinized, since several test parameters were not based on observations of the human physiology. Conclusion: The limited comparability and restricted clinical implications should be kept in mind when interpreting the results of biomechanical studies and when designing test setups to evaluate fixation methods for acetabular fractures.Publicationtype: Journal ArticleScopus© Citations 6 82 180 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Biomechanical analysis of anterior pelvic ring fractures with intact peripelvic soft tissues: a cadaveric studyPurpose: Biomechanical studies of the pelvis are usually performed using dissected pelvic specimens or synthetic bones. Thereby the stabilising effect of the surrounding soft tissues is analysed insufficiently. Biomechanical data for isolated anterior pelvic ring fractures are currently missing. Therefore, the purpose of this study was to develop a novel testing device for biomechanical analyses of the pelvis and to investigate two different anterior pelvic ring fractures in a cadaveric model with intact peripelvic soft tissues. Methods: A new biomechanical table construction which enables the fixation and testing of complete cadaveric specimens was developed. It was used to investigate the relative motion and stiffness changes due to unilateral osteotomy of the superior and inferior pubic ramus. Five cadavers with a mean age of 55.6 years (± 15.53 years) were included and loaded with a sinusoidal, cyclic (1 Hz), compressive force of up to 365 N over ten cycles for each condition. Results: Biomechanical testing of the pelvis with complete appended soft tissues was feasible. Native stiffness without a pelvic fracture was 64.31 N/mm (± 8.33 N/mm). A standardised unilateral osteotomy of the superior pubic ramus reduced the stiffness under isolated axial load by 2% (63.05 N/mm ± 7.45 N/mm, p = 0.690). Additional osteotomy of the inferior pubic ramus caused a further, statistically not significant, decrease by 5% (59.57 N/mm ± 6.84 N/mm, p = 0.310). Conclusions: The developed test device was successfully used for biomechanical analyses of the pelvis with intact peripelvic soft tissues. In a first study, isolated unilateral fractures of the anterior pelvic ring showed no relevant biomechanical variation compared to the intact situation under isolated axial load. Only 7% of the measured stiffness was created by both unilateral pubic rami. Therefore, the clinical practice to treat unilateral anterior pelvic ring fractures conservatively is supported by the results of this study.Publicationtype: Journal Article389 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Biomechanical aspects of the posteromedial split in bicondylar tibial plateau fractures—a finite-element investigationPurpose: To gain principal insight into fixation techniques of a posteromedial split fragment in bicondylar tibial plateau fractures. Methods: A computer simulation was performed, applying the finite-element method (FEM) to compare four methods of fixation of the posteromedial split fragment: lateral plate (model 1), lateral plate and kickstand screw (model 2), lateral plate and two antero-posterior lag screws (model 3), and lateral and posteromedial plate (model 4). The displacement of the fragment and material stresses in implants and bone under 2500 N axial load were analyzed. Results: Maximal displacement of the posteromedial split fragment of 2.8 mm was found with a sole lateral plate. An added kickstand screw decreased the displacement to 1.46 mm. Added lag screws improved stability by a factor 4, with a maximal displacement of 0.76 mm. The double-plate configuration revealed 0.27 mm, a decrease of the displacement by a factor 10 compared to model 1. An additional analysis of posteromedial fragment displacements with osteoporotic bone, simulated by dividing the elastic modulus of the bone by a factor 2, turned out to be of relevant impact. For model 1, the calculations did not converge. The influence of bone quality was found to be 70% in model 2, 60% in model 3, and 40% in model 4. Conclusions: The results indicate that the additional fixation of a posteromedial split fracture by plate osteosynthesis might be advantageous in bicondylar tibial plateau fractures treated with lateral plating. This might be even more important in patients with low bone quality.Publicationtype: Journal Article109