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Item type:Publication, Access status: with files , Experimental determination of the stabbing intensity in an intracranial stabbing death(Springer, 2026); ; ; 9 23 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Biomechanical principles of a permanently durable abdominal wall reconstruction: current status and potential future development(OAE Publishing, Inc, 2023-07-25); ; ; The article reviews the biomechanical principles of durable abdominal wall reconstructions. The aim is to provide insights and conclusions for future research in this area. Incisional hernia repair implies the creation of a compound made of tissue, textile, and fixation elements. A pulse load bench test for incisional hernia repair has been available since 2014, and its influences are evaluated in three different versions of the test stand. Based on these evaluations, a biomechanical concept for long-term durable reconstructions was determined. To apply the concept to individual patients, computed tomography of the abdomen at rest and during the Valsalva maneuver was used. A load limit can be given for every patient based on the hernia defect area (CRIP- critical resistance to impacts related to pressure). By considering the mesh to defect area ratio, the retention strength of a planned reconstruction can be calculated (GRIP-gained resistance to impacts related to pressure). The gripping coefficients for tissues vary significantly, up to 18 fold. About half of the patients have overall tissue distensions up to 350% or more, with potential high regional variations. The surface retention forces for hernia meshes and for different sutures, tacks, and adhesives span a wide range of 14fold. Suturing a defect strengthens the reconstruction up to 3fold. Furthermore, recalculating data taken from multicentric randomized studies on primary sutures reveals that improved GRIP values are associated with reduced rates of incisional hernia. Repairing consecutive incisional hernias according to the GRIP concept results in no recurrence and low pain levels after one year. A future policy for market access of repair materials should include cyclic load bench testing. Moreover, a tailored approach to incisional hernia repair should take into account the biomechanical aspects involved.Publicationtype: Review ArticleScopus© Citations 1 27 113 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Cyclic pulse loads pave the road to the GRIP concept in abdominal wall reconstruction(OAE Publishing, Inc, 2023-07-10); ; ; Aim: Durable reconstruction of the abdominal wall needs to be assessed in a lifelike experimental setting and consider the reconstructed abdominal wall as a coherent compound. Our aim was to evaluate broader possibilities in preclinical testing and to deepen the understanding of the biomechanical influences. Methods: We developed a test bench that allows studying a compound under cyclic, repetitive loads. Pulse loads transmit energy to the abdominal wall repeatedly. The amount of energy is related to the load characteristics. We used porcine bellies with a round central (5 cm) defect. They were bridged in a sublay position with Cicat Dynamesh®. Further defects, located in an additional incision, were sutured in a standardized small-bite technique. We varied the number of loads, the maximum peak pressure, the pressure plateau length, and the impact area size. Results: Increasing the peak pressure by 30 mmHg lowers the durability by about 20 %. Prolonging the plateau phase led to a significant durability decrease. During the first 100 dynamic intermittent strain (DIS) impacts, the major tissue deformation and the majority of failures occur. Beyond the 425th DIS impact, about 10 % more failures occur. Increasing elongation and deformation of the tissue raise the likelihood of failure. Conclusion: If the compound does not establish a strain-stable condition during the period of plastic deformation, failure occurs. The outcome does not only depend on the reconstruction technique but also on the external influences acting on the abdominal wall compound. Considering the biomechanical reality is important for open and minimally invasive abdominal wall reconstruction.Publicationtype: Journal ArticleScopus© Citations 2 23 96 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Biomechanisch stabile Bauchwand-Rekonstruktion : Schritt für Schritt zum Erfolg(Kaden, 2023-03); ; ; ; Publicationtype: Journal Article17 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Cyclic pulse loads generate the new concept in abdominal wall reconstruction: suture closure(OAE Publishing, Inc, 2023); ; ; Aim: Incisional hernias frequently occur after open abdominal surgery. Up to 30% of elective midline laparotomy closures result in an incisional hernia. The properties of a safe abdominal wall reconstruction must be assessed under lifelike conditions to obtain a realistic estimate of the durability. The interplay of the biomechanical qualities determines the long-term stability of a repair. Various suture materials and techniques for optimal closure of the abdominal wall are still under discussion. The results of this experimental study might significantly affect the active discussion about optimal suturing techniques for median abdominal wall closure. Methods: For this purpose, a bench test was developed that delivers repetitive cyclic pressure impacts to the abdominal wall, simulating coughs. This allows the assessment of the reconstructed abdominal wall as a compound. We used stiff porcine abdominal walls and elastic bovine flanks as model tissues. We chose two different types of defects. Type one consisted of a 15 cm long medial incision, whereas for type two, a 5 cm circular defect was added in the center of the incision. The incisions were solely sutured in large-bite (0.8-1.2 mm bites) or small-bite (0.5-0.8 mm bites) technique with Monomax® or PDS® sutures USP 2-0 or USP 1. The suture to wound length (SWL) ratio had to exceed 4:1. After suturing, the tissues were subjected to repetitive cyclic loading on a validated bench test. Results: We found that regardless of technique and material thickness, secure closure of median abdominal wall incisions is feasible by suturing. In larger defects, the small bites technique using Monomax® sutures achieves a safer closure compared to PDS® sutures. Conclusion: Based on the results of this experimental study, a tailored standardized closure technique after midline incision of the abdominal wall, including an optional mesh augmentation, is recommended.Publicationtype: Journal ArticleScopus© Citations 1 20 113 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Standardized suturing can prevent slackening or bursting suture lines in midline abdominal incisions and defects(Springer, 2022-08-23); ; ; ; Purpose: Incisional hernias often follow open abdominal surgery. A small-stitch–small-bite suture might close the incision durably. We analyzed specific details of this closure technique and assessed their influence on the closure stability. Methods: The effects of cyclic loads, simulating coughs were investigated on a bench test. We prepared porcine bellies in the median line and bovine flanks parallel to the muscle fibers with 15 cm long incisions. Then we punched round or rhomboid defects with a diameter of 5–10 cm into the center of the incision. Monomax® 2–0 and Maxon® 1 and 2–0 were used as suture materials. We tested the durability of the closure with pressure impacts of 210 mmHg repeated 425 times. Throughout the experiments, we modified the suturing technique, the surgeon, the tissue tension, the defect size and shape and the suture diameter. Results: Standardizing the suture technique improved the durability of the closure significantly. Any other variations showed minor influences after standardization. All incisions with round defects up to 7.5 cm width withstood 425 impacts using standardized suturing. Unstandardized sutures failed in all cases. When closing an incision with a 10 cm wide defect, the tissues ruptured frequently next to the suture line. We defined criteria to standardize this suturing technique. For the first time, we developed a suture factor related to the durability of a sutured tissue closure. We integrated the suture factor into the concept of biomechanically durable repairs. Conclusions: Suturing the abdominal wall with a standardized suturing technique improves its durability significantly.Publicationtype: Journal ArticleScopus© Citations 7 45 87 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Primary and recurrent repair of incisional hernia based on biomechanical considerations to avoid mesh-related complications(Frontiers Media S.A., 2021-12-15); ; ; ; Aim: Mechanical principles successfully guide the construction of polymer material composites in engineering. Since the abdominal wall is a polymer composite augmented with a textile during incisional hernia repair we ask: can incisional hernia be repaired safely and durably based on biomechanical principles? Material and Methods: Repair materials were assessed on a self-built bench test using pulse loads to elude influences on the reconstruction of the abdominal wall. Tissue elasticity was analyzed preoperatively as needed with computed tomography at rest and during Valsalva's maneuver. Preoperatively, the critical retention force of the reconstruction to pulse loads was calculated and a biomechanically durable repair was designed based on the needs of the individual patient. Intraoperatively, the design was adjusted as needed. Hernia meshes with high grip factors (Progrip®, Dahlhausen® Cicat) were used for the repairs. Mesh sizes, fixation elements and reconstructive details were oriented on the biomechanical design. All patients recieved single-shot antibiosis. Patients were discharged after full ambulation was achieved. Results: A total of 163 patients (82 males and 81 females) were treated for incisional hernia in four hospitals by ten surgeons. Primary hernia was repaired in 119 patients. Recurrent hernia was operated on in 44 cases. Recurrent hernia was significantly larger (median 161 cm2 vs. 78 cm2; u-test: p = 0.00714). Re-do surgery took significantly longer (median 229 min vs. 150 min; p < 0.00001) since recurrent disease required more often transversus abdominis release (70% vs. 47%). GRIP tended to be higher in recurrent repair (p = 0.01828). Complication rates (15%) and hospital stay were the same (6 vs. 6 days; p = 0.28462). After 1 year, no recurrence was detected in either group. Pain levels were equally low in both primary and recurrent hernia repairs (median NAS = 0 in both groups at rest and under load, p = 0.88866). Conclusion: Incisional hernia can safely and durably be repaired based on biomechanical principles both in primary and recurrent disease. The GRIP concept provides a base for the application of biomechanical principles in incisional hernia repair.Publicationtype: Journal ArticleScopus© Citations 13 125 182 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Biomechanical Influences on mesh-related complications in incisional hernia repair(Frontiers Media S.A., 2021-10-29); ; ; ; Aim: Hernia repair strengthens the abdominal wall with a textile mesh. Recurrence and pain indicate weak bonds between mesh and tissue. It remains a question which biomechanical factors strengthen the mesh-tissue interface, and whether surgeons can enhance the bond between mesh and tissue. Material and Methods: This study assessed the strength of the mesh-tissue interface by dynamic loads. A self-built bench test delivered dynamic impacts. The test simulated coughing. Porcine and bovine tissue were used for the bench test. Tissue quality, mesh adhesiveness, and fixation intensity influenced the retention power. The influences were condensed in a formula to assess the durability of the repair. The formula was applied to clinical work. The relative strength of reconstruction was related to the individual human abdominal wall. From computerized tomography at rest and during Valsalva's Maneuver, the tissue quality of the individual patient was determined before surgery. Results: The results showed that biomechanical parameters observed in porcine, bovine, and human tissue were in the same range. Tissues failed in distinct patterns. Sutures slackened or burst at vulnerable points. Both the load duration and the peak load increased destruction. Stress concentrations elevated failure rates. Regional areas of force contortions increased stress concentrations. Hernia repair improved strain levels. Measures for improvement included the closure of the defect, use of higher dynamic intermittent strain (DIS) class meshes, increased mesh overlap, and additional fixation. Surgeons chose the safety margin of the reconstruction as desired. Conclusion: The tissue quality has now been introduced into the concept of a critical and a gained resistance toward pressure-related impacts. A durable hernia repair could be designed from available coefficients. Using biomechanical principles, surgeons could minimize pain levels. Mesh-related complications such as hernia recurrence can potentially be avoided in incisional hernia repair.Publicationtype: Journal ArticleScopus© Citations 13 140 243 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , The grip concept of incisional hernia repair - dynamic bench test, CT abdomen with valsalva and 1-year clinical results(Frontiers Media S.A., 2021-04-14); ; ; ; Incisional hernia is a frequent consequence of major surgery. Most repairs augment the abdominal wall with artificial meshes fixed to the tissues with sutures, tacks, or glue. Pain and recurrences plague at least 10–20% of the patients after repair of the abdominal defect. How should a repair of incisional hernias be constructed to achieve durability? Incisional hernia repair can be regarded as a compound technique. The biomechanical properties of a compound made of tissue, textile, and linking materials vary to a large extent. Tissues differ in age, exercise levels, and comorbidities. Textiles are currently optimized for tensile strength, but frequently fail to provide tackiness, dynamic stiction, and strain resistance to pulse impacts. Linking strength with and without fixation devices depends on the retention forces between surfaces to sustain stiction under dynamic load. Impacts such a coughing or sharp bending can easily overburden clinically applied composite structures and can lead to a breakdown of incisional hernia repair. Our group developed a bench test with tissues, fixation, and textiles using dynamic intermittent strain (DIS), which resembles coughing. Tissue elasticity, the size of the hernia under pressure, and the area of instability of the abdominal wall of the individual patient was assessed with low-dose computed tomography of the abdomen preoperatively. A surgical concept was developed based on biomechanical considerations. Observations in a clinical registry based on consecutive patients from four hospitals demonstrate low failure rates and low pain levels after 1 year. Here, results from the bench test, the application of CT abdomen with Valsalva's maneuver, considerations of the surgical concept, and the clinical application of our approach are outlined.Publicationtype: Journal ArticleScopus© Citations 20 105 180 - 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