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Item type:Publication, Access status: with files , Distal cortical notching significantly decreases tibial stability following tibial tubercle osteotomy: an in vitro porcine biomechanical study(Wiley, 2026-07-17); ; ; ; Purpose: Distalizing tibial tubercle osteotomy (dTTO) is an effective treatment for patella alta, yet complications can be severe. This study evaluates the biomechanical effects of distal cut orientation on tibial fracture risk. It was hypothesised that orthogonal cutting and cortical notching reduce tibial stability. Methods: A total of 61 porcine tibiae were tested in three setups. Four distal cut orientations were compared in a load-to-failure analysis (n = 32): oblique (Obl), orthogonal without notch (Orth), orthogonal 2-mm notch (Orth2), orthogonal 4-mm notch (Orth4) (each n = 8). Cyclic loading was evaluated in Obl, Orth and Orth2 (n = 17), followed by comparison of plate versus (2-hole one-third tubular plate) 3.5-mm screw fixation in Orth2 specimens (n = 12). Specimens were embedded in PMMA and axially loaded (MTS Bionix 358). Load-to-failure, stiffness and cycles until failure were recorded. Residual tibial thickness was measured. Linear regression analysed the relationship between residual thickness and failure load. Statistical analysis included t-tests and ANOVA (α = 0.05). Results: Obl showed the highest failure load (784.5 N ± 118.3), although the difference compared to Orth (538.8 N ± 229.5, p = 0.087) did not reach statistical significance. Notching significantly reduced load-to-failure (2-mm: 294.0 N ± 91.8; 4 mm: 274.6 N ± 96.5). In cyclic testing, Obl withstood most cycles until failure (5894 ± 2187) compared to Orth (3142 ± 808; p = 0.004), while Orth2 failed sooner (1400 ± 530, all p < 0.005). Osteosynthesis techniques did not affect failure load (p = 0.802). Stiffness and residual tibial thickness were comparable. Distal tibial thickness was associated with failure load in all groups (all p < 0.05). Conclusion: In this porcine model, cortical notching significantly reduced tibial stability and should be avoided during TTO. Oblique distal cuts demonstrated greater resistance to cyclic loading, while no significant difference was observed in static load-to-failure. Osteosynthesis technique did not affect load-to-failure. Level of Evidence: NA, cadaveric biomechanical study.Publicationtype: Journal Article25 6 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Acromioclavicular joint suture button repair leads to coracoclavicular tunnel wideningPurpose: Biomechanical evaluation of three different suture button devices used in acromioclavicular joint repair and analysis of their effect on post-testing tunnel widening. Methods: Eighteen human shoulder girdles were assigned into three groups with a similar mean bone mineral density. Three different single-tunnel acromioclavicular repair devices were tested: (1) AC TightRope® with FiberWire; (2) AC Dog Bone™ Button with FiberTape; (3) Low Profile AC Repair System. Biomechanical testing was performed simulating the complex movement of the distal clavicle as follows. A vertical load of 80 N was applied continuously. The rotation of the clavicle about its long axis was set at 10° anterior and 30° posterior for 2500 cycles at 0.25 Hz. The horizontal translation of the clavicle was set at 6 mm medial and 6 mm lateral for 10,000 cycles at 1 Hz. The coracoclavicular distance was measured before and after testing. After testing, each sample underwent micro-CT analysis. Following 3D reconstruction, the area of the bone tunnels was measured at five defined cross sections. Results: In TightRope® and Dog Bone™ groups, all samples completed testing, whereas in the Low Profile group, three out of six samples showed system failure. The mean absolute difference of coracoclavicular distance after testing was significantly greater in the Low Profile group compared to TightRope® and Dog Bone™ groups (4.3 ± 1.3 mm vs 1.9 ± 0.7 mm vs 1.9 ± 0.8 mm; p = 0.001). Micro-CT analysis of the specimens demonstrated significant tunnel widening in the inferior clavicular and superior coracoid regions in all three groups (p < 0.05). Conclusion: Significant tunnel widening can be observed for all devices and is primarily found in the inferior parts of the clavicle and superior parts of the coracoid. The Low Profile AC Repair System showed inferior biomechanical properties compared to the AC TightRope® and AC Dog Bone™ devices. Therefore, clinicians should carefully select the type of acromioclavicular repair device used and need to consider tunnel widening as a complication.Publicationtype: Journal ArticleScopus© Citations 5 58 136 - Some of the metrics are blocked by yourconsent settings
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 , Stresses and deformations of an osteosynthesis plate in a lateral tibia plateau fracture(2022-01-01); ; ; ; This study has the aim to investigate the strain and stress in an anterolateral locking plate applied for the fixation of a lateral split fracture. To simulate a complex fracture situation, three segments were separated. With a FEM analysis, representative places for strain and stress measurement were determined. A locked osteosynthesis plate was instrumented with strain gauges and tested on a fractured and a non-fractured Saw Bone model. To simulate different loading situations, four different points of force application, from the center of the condyles to a 15 mm posterior position, were used with a medial-lateral load distribution of 60:40. The simulations as well as the biomechanical tests demonstrated that two deformations dominate the load on the plate: a bending into posterior direction and a bulging of the plate head. Shifting the point of application to the posterior direction resulted in increasing maximum stress, from 1.16 to 6.32 MPa (FEM analysis) and from 3.04 to 7.00 MPa (biomechanical study), respectively. Furthermore, the comparison of the non-fractured and fractured models showed an increase in maximum stress by the factor 2.06-2.2 (biomechanical investigation) and 1.5-3.3 (FEM analysis), respectively.Publicationtype: Journal ArticleScopus© Citations 2 47 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , All-suture anchor pullout results in decreased bone damage and depends on cortical thickness(Springer, 2021-07); ; ; ; Purpose: To evaluate the influence of cortical and cancellous bone structure on the biomechanical properties of all-suture and conventional anchors and compare the morphological bone damage after their failure. The hypothesis of the study is that all-suture anchor pullout is less invasive and that the pullout force is influenced by the cortical thickness. Methods: Thirty human humeri were biomechanically tested as follows: starting with a load cycle from 20 to 50 N, a stepwise increase of the upper peak force by 0.05 N for each cycle at a rate of 1 Hz was performed. Analysis included maximum pullout strength for three different anchor implantation angles (45°, 90°, 110°) of the two anchor types. After anchor pullout, every sample underwent micro-CT analysis. Bone mineral density (BMD) and cortical thickness were determined at the anchor implantation site. Furthermore, the diameter of the cortical defect and the volume of the bone cavity were identified. Results: The maximum pullout strength of all-suture anchors demonstrates a strong correlation to the adjacent cortical thickness (r = 0.82, p ≤ 0.05) with at least 0.4 mm needed to withstand 200 N. No correlation could be seen in conventional anchors. Moreover, no correlation could be detected for local BMD in both anchors. All-suture anchors show a significantly narrower cortical defect as well as a smaller bone cavity following pullout (4.3 ± 1.3 mm vs. 5.3 ± 0.9 mm, p = 0.037; 141 mm3 vs. 212 mm3; p = 0.009). The cortical defect is largest if the anchors are placed at a 45° angle. Conclusion: In contrast to conventional anchors, the pullout force of all-suture anchors depends on the thickness of the humeral cortex. Furthermore, all-suture anchors show a significantly smaller cortical defect as well as decreased bone damage in the case of pullout. Therefore, the clinical implication of this study is that all-suture anchors are advantageous due to their bone preserving ability. Also, intraoperative decortication should not be performed and cortical thickness should be preoperatively evaluated to decrease the risk of anchor failure.Publicationtype: Journal ArticleScopus© Citations 23 180 156 - 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 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Ausriss von All-suture-Ankern verursacht geringere Knochenschäden und ist von der Kortikalisdicke abhängig [All-suture anchor pullout results in decreased bone damage and depends on cortical thickness](2020-09-01); ; ; ; Purpose: To evaluate the influence of cortical and cancellous bone structure on the biomechanical properties of all-suture and conventional anchors and compare the morphological bone damage after their failure. The hypothesis of the study is that all-suture anchor pullout is less invasive and that the pullout force is influenced by the cortical thickness. Methods: Thirty human humeri were biomechanically tested as follows starting with a load cycle from 20 to 50 N, a stepwise increase of the upper peak force by 0.05 N for each cycle at a rate of 1 Hz was performed. Analysis included maximum pullout strength for three different anchor implantation angles (45°, 90°, 110°) of the two anchor types. After anchor pullout, every sample underwent micro-CT analysis. Bone mineral density (BMD) and cortical thickness were determined at the anchor implantation site. Furthermore, the diameter of the cortical defect and the volume of the bone cavity were identified. Results: The maximum pullout strength of all-suture anchors demonstrates a strong correlation to the adjacent cortical thickness (r = 0.82, p ≤ 0.05) with at least 0.4 mm needed to withstand 200 N. No correlation could be seen in conventional anchors. Moreover, no correlation could be detected for local BMD in both anchors. All-suture anchors show a significantly narrower cortical defect as well as a smaller bone cavity following pullout (4.3 ± 1.3 mm vs. 5.3 ± 0.9 mm, p = 0.037; 141 mm3 vs. 212 mm3; p = 0.009). The cortical defect is largest if the anchors are placed at a 45° angle. Conclusion: In contrast to conventional anchors, the pullout force of all-suture anchors depends on the thickness of the humeral cortex. Furthermore, all-suture anchors show a significantly smaller cortical defect as well as decreased bone damage in the case of pullout. Therefore, the clinical implication of this study is that all-suture anchors are advantageous due to their bone preserving ability. Also, intraoperative decortication should not be performed and cortical thickness should be preoperatively evaluated to decrease the risk of anchor failure.Publicationtype: Journal Article119 1 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Biomechanical analysis of conventional anchor revision after all-suture anchor pullout: a human cadaveric shoulder model(2019-12); ; ; ; Hypothesis and background: The possibility of implanting a conventional anchor at the pullout site following all-suture anchor failure was evaluated in a biomechanical cadaveric model. The hypothesis of the study was that anchor revision would yield equal biomechanical properties. Methods: Ten human humeri were obtained, and bone density was determined via computed tomography. After all-suture anchor (n = 5) and conventional 4.5-mm anchor (n = 5) insertion, biomechanical testing was conducted. Following all-suture anchor pullout, a conventional 5.5-mm anchor was inserted at the exact site of pullout (n = 5) and biomechanical testing was reinitiated. Testing was conducted using an initial preload of 20 N, followed by an unlimited cyclic protocol, with a stepwise increasing force of 0.05 N for each cycle at a rate of 1 Hz until system failure. The number of cycles, maximum load to failure, stiffness, displacement, and failure mode, as well as macroscopic observation at the failure site including diameter, shape, and cortical destruction, were registered. Results: The defect following all-suture pullout showed a mean diameter of 4 mm, and conventional revision was possible in each sample. There was no significant difference between the initial all-suture anchor implantation and the conventional anchor implantation or the conventional revision following all-suture failure regarding mean pullout strength, stiffness, displacement, or total number of cycles until failure. Conclusion: Conventional anchor revision at the exact same site where all-suture anchor pullout occurred is possible and exhibits similar biomechanical properties.Publicationtype: Journal Article187 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Conventional rotator cuff versus all-suture anchors — a biomechanical study focusing on the insertion angle in an unlimited cyclic model(Public Library of Science (PLoS), 2019-11-27); ; ; ; This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Purpose The purpose of this study was to compare the biomechanical properties of an all-suture anchor to a conventional anchor used commonly in rotator cuff repairs. Furthermore, the biomechanical influence of various implantation angles was evaluated in both anchor types in a human cadaveric model. Methods 30 humeri were allocated into three groups with a similar bone density. The two different anchor types were inserted at a predefined angle of 45o, 90o or 110o. Biomechanical testing included an initial preload of 20N followed by a cyclic protocol with a stepwise increasing force of 0,05N for each cycle at a rate of 1Hz until system failure. Number of cycles, maximum load to failure, stiffness, displacement and failure mode were determined. Results 27 anchors failed by pullout. There was no significant difference between the conventional and the all-suture anchor regarding mean pullout strength. No considerable discrepancy in stiffness or displacement could be perceived. Comparing the three implantation angles no significant difference could be observed for the all-suture or the conventional anchor. Conclusion All-suture anchors show similar biomechanical properties to conventional screw shaped anchors in an unlimited cyclic model. The exact insertion angle is not a significant predictor of failure.Publicationtype: Journal ArticleScopus© Citations 19 439 366