Three-year follow-up of the grip concept: an open, prospective, observational registry study on biomechanically calculated abdominal wall repair for complex incisional hernias.

PURPOSE: We studied the effectiveness of biomechanically calculated abdominal wall reconstructions for incisional hernias of varying complexity in an open, prospective observational registry trial. METHODS: From July 1st, 2017 to December 31st, 2020, four hospitals affiliated with the University of Heidelberg recruited 198 patients with complex incisional hernias. Hernias were repaired using biomechanically calculated reconstructions and materials classified on their gripping force towards cyclic load. This approach determines the required strength preoperatively based on the hernia size, using the Critical Resistance to Impacts related to Pressure. The surgeon is supported in reliably determining the Gained Resistance, which is based on the mesh-defect-area-ratio, as well as other mesh and suture factors, and the tissue stability. Tissue stability is defined as a maximum distension of 1.5 cm upon a Valsalva maneuver. In complex cases, a CT scan of the abdomen can be used to assess unstable tissue areas both at rest and during Valsalva's maneuver. RESULTS: Larger and stronger gripping meshes were required for more complex cases to achieve a durable repair, especially for larger hernia sizes. To achieve durable repairs, the number of fixation points increased while the mesh-defect area ratio decreased. Performing these repairs required more operating room time. The complication rate remained low. Less than 1% of recurrences and low pain levels were observed after 3 years. CONCLUSIONS: Biomechanical stability, defined as the resistance to cyclic load, is crucial in preventing postoperative complications, including recurrences and chronic pain.

STRONGHOLD first-year results of biomechanically calculated abdominal wall repair: a propensity score matching.

PURPOSE: Every year around 70,000 people in Germany suffer from an abdominal incisional hernia that requires surgical treatment. Five years after reconstruction about 25% reoccur. Incisional hernias are usually closed with mesh using various reconstruction techniques, summarized here as standard reconstruction (SR). To improve hernia repair, we established a concept for biomechanically calculated reconstructions (BCR). In the BCR, two formulas enable customized patient care through standardized biomechanical measures. This study aims to compare the clinical outcomes of SR and BCR of incisional hernias after 1 year of follow-up based on the Herniamed registry. METHODS: SR includes open retromuscular mesh augmented incisional hernia repair according to clinical guidelines. BCR determines the required strength (Critical Resistance to Impacts related to Pressure = CRIP) preoperatively depending on the hernia size. It supports the surgeon in reliably determining the Gained Resistance, based on the mesh-defect-area-ratio, further mesh and suture factors, and the tissue stability. To compare SR and BCR repair outcomes in incisional hernias at 1 year, propensity score matching was performed on 15 variables. Included were 301 patients with BCR surgery and 23,220 with standard repair. RESULTS: BCR surgeries show a significant reduction in recurrences (1.7% vs. 5.2%, p = 0.0041), pain requiring treatment (4.1% vs. 12.0%, p = 0.001), and pain at rest (6.9% vs. 12.7%, p = 0.033) when comparing matched pairs. Complication rates, complication-related reoperations, and stress-related pain showed no systematic difference. CONCLUSION: Biomechanically calculated repairs improve patient care. BCR shows a significant reduction in recurrence rates, pain at rest, and pain requiring treatment at 1-year follow-up compared to SR.

Standardized suturing can prevent slackening or bursting suture lines in midline abdominal incisions and defects.

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.

Biomechanics applied to incisional hernia repair - Considering the critical and the gained resistance towards impacts related to pressure.

BACKGROUND: Incisional hernia repair is burdened with recurrence, pain and disability. The repair is usually carried out with a textile mesh fixed between the layers of the abdominal wall. METHODS: We developed a bench test with low cyclic loading. The test uses dynamic intermittent strain resembling coughs. We applied preoperative computed tomography of the abdomen at rest and during Valsalva's maneuver to the individual patient to analyze tissue elasticity. FINDINGS: The mesh, its placements and overlap, the type and distribution of fixation elements, the elasticity of the tissue of the individual and the closure of the abdominal defect-all aspects influence the reconstruction necessary. Each influence can be attributed to a relative numerical quantity which can be summed up into a characterizing value. The elasticity of the tissues within the abdominal wall of the individual patient can be assessed with low-dose computed tomography of the abdomen with Valsalva's maneuver. We established a procedure to integrate the results into a surgical concept. We demonstrate potential computer algorithms using non-rigid b-spline registration and artificial intelligence to further improve the evaluation process. INTERPRETATION: The bench test yields relative values for the characterization of hernia, mesh and fixation. It can be applied to patient care using established procedures. The clinical application in the first ninety-six patients shows no recurrences and reduced pain levels after one year. The concept has been spread to other surgical groups with the same results in another fifty patients. Future efforts will make the abdominal wall reconstruction more predictable.

Increasing hernia size requires higher GRIP values for a biomechanically stable ventral hernia repair.

BACKGROUND: Increasing hernia sizes lead to higher recurrence rates after ventral hernia repair. A better grip might reduce the failure rates. MATERIAL AND METHODS: A biomechanical model delivering dynamic intermittent strain (DIS) was used to assess grip values at various hernia orifices. The model consists of a water-filled aluminium cylinder covered with tissues derived from pig bellies which are punched with a central defect varying in diameter. DIS was applied mimicking coughs lasting for up to 2 s with peak pressures between 180 and 220 mmHg and a plateau phase of 0.1 s. Ventral hernia repair was simulated with hernia meshes in the sublay position secured by tacks, glue or sutures as needed to achieve certain grip values. Grip was calculated taking into account the mesh: defect area ratio and the fixation strength. Data were assessed using non-parametric statistics. RESULTS: Using a mesh classified as highly stable upon DIS testing (DIS class A) a reduced overlap without fixation led to early slippage (p < 0.001). With the application of 16 fixation points, transmural sutures were better than tacks with Securestrap® being better than Absorbatack® (p < 0.001). Plotting the likelihood of a durable repair as a function of the calculated grip higher grip values were needed with increasing hernia diameter to achieve biomechanical stability. This is important for clinical work since the calculated grip values both from a registry and from published data tend to drop as hernia sizes increase indicating biomechanical instability. CONCLUSION: The experimental work reported here demonstrates for the first time that higher grip values should be reached when repairing larger ventral hernias.

What is the evidence for the use of biologic or biosynthetic meshes in abdominal wall reconstruction?

INTRODUCTION: Although many surgeons have adopted the use of biologic and biosynthetic meshes in complex abdominal wall hernia repair, others have questioned the use of these products. Criticism is addressed in several review articles on the poor standard of studies reporting on the use of biologic meshes for different abdominal wall repairs. The aim of this consensus review is to conduct an evidence-based analysis of the efficacy of biologic and biosynthetic meshes in predefined clinical situations. METHODS: A European working group, "BioMesh Study Group", composed of invited surgeons with a special interest in surgical meshes, formulated key questions, and forwarded them for processing in subgroups. In January 2016, a workshop was held in Berlin where the findings were presented, discussed, and voted on for consensus. Findings were set out in writing by the subgroups followed by consensus being reached. For the review, 114 studies and background analyses were used. RESULTS: The cumulative data regarding biologic mesh under contaminated conditions do not support the claim that it is better than synthetic mesh. Biologic mesh use should be avoided when bridging is needed. In inguinal hernia repair biologic and biosynthetic meshes do not have a clear advantage over the synthetic meshes. For prevention of incisional or parastomal hernias, there is no evidence to support the use of biologic/biosynthetic meshes. In complex abdominal wall hernia repairs (incarcerated hernia, parastomal hernia, infected mesh, open abdomen, enterocutaneous fistula, and component separation technique), biologic and biosynthetic meshes do not provide a superior alternative to synthetic meshes. CONCLUSION: The routine use of biologic and biosynthetic meshes cannot be recommended.

Bridging with reduced overlap: fixation and peritoneal grip can prevent slippage of DIS class A meshes.

PURPOSE: Ventral hernia repair can be performed safely using meshes which are primarily stable upon dynamic intermittent straining (DIS) at recommended overlap. In specific clinical situations, e.g., at bony edges, bridging of the hernial orifice with reduced overlap might be necessary. To gain insight into the durability of various applications, two different meshes with the best tissue grip known so far were assessed. METHODS: The model uses dynamic intermittent strain and comprises the repetition of submaximal impacts delivered via a hydraulically driven plastic containment. Pig tissue simulates a ventral hernia with a standardized 5 cm defect. Commercially available meshes classified as primarily stable at recommended overlap were used to bridge this defect at recommended and reduced overlap. RESULTS: Using Parietex Progrip®, the peritoneum adds sufficient stability at least to a 2.5 cm overlap. Using Dynamesh Cicat®, four gluing spots with Glubran® are sufficient to stabilize a 3.75 cm overlap. A 2.5 cm overlap is stabilized with eight bonding spots Glubran® and 8 bonding spots combined with four sutures stabilize a 1.25 cm overlap. Here again, an intact peritoneum stabilizes the reconstruction significantly. CONCLUSIONS: Based on a pig tissue model, a total of 23 different conditions were tested. A DIS class A mesh can be easily stabilized bridging a 5 cm hernial orifice with reduced overlap. Caution must be exerted to extend these results to other DIS classes and larger hernial orifices. Further DIS investigations can improve the durability of hernia repair.

Development of a dynamic model for ventral hernia mesh repair.

INTRODUCTION: The adequate way of mesh fixation in laparoscopic ventral hernia repair is still subject to debate. So far, simulation has only been carried out in a static way, thereby omitting dynamic effects of coughing or vomiting. We developed a dynamic model of the anterior abdominal wall. MATERIALS AND METHODS: An aluminium cylinder was equipped with a pressure controlled, fluid-filled plastic bag, simulating the abdominal viscera. A computer-controlled system allowed the control of influx and efflux, thus creating pressure peaks of up to 200 mmHg to simulate coughing and 290 mmHg to simulate vomiting. We tested fixation with tacks (Absorbatack, Covidien Deutschland, Neustadt a. D., Germany). The model was controlled for the friction coefficient of the tissue against the mesh and the physiologic elasticity of the abdominal wall surrogate. RESULTS: The model was able to create pressure peaks equivalent to physiologic coughs or vomiting. Physiologic elasticity was thereby maintained. We could show that the friction coefficient is crucial to achieve a physiologic situation. The meshes showed a tendency to dislocate with an increasing number of coughs (Fig. 4). Nevertheless, when applied in a plain manner, the meshes withstood more cough cycles than when applied with a bulge as in laparoscopic surgery. CONCLUSIONS: The dynamic movement of the abdominal wall, the friction between tissue and mesh and the way of mesh application are crucial factors that have to be controlled for in simulation of ventral abdominal hernia closure. We could demonstrate that patient specific factors such as the frequency of coughing as well as the application technique influence the long term stability of the mesh.

[Evaluation of traditional German undergraduate surgical training. An analysis at Heidelberg University]. / Evaluation der traditionellen studentischen Ausbildung in der Chirurgie. Eine Heidelberger Bestandsaufnahme.

BACKGROUND: The medical faculty of Heidelberg University implemented a new problem-based clinical curriculum (Heidelberg Curriculum Medicinale, or Heicumed) in 2001. The present study analyses the evaluation data of two student cohorts prior to the introduction of Heicumed. Its aim was to specify problems of the traditional training and to draw conclusions for implementation of a new curriculum. METHODS: The evaluation instrument was the Heidelberg Inventory for the Evaluation of Teaching (HILVE-I). The data were analysed calculating differences in the means between defined groups, with the 13 primary scales of the HILVE I-instrument as dependent variables. RESULTS: Teaching method and subject had no systematic influence on evaluation results. Thus, didactic lecture in orthopedic surgery achieved better results than small group tutorials, while the data on vascular and general surgery showed opposite results. Major factors for success were continuity and didactic training of lecturers and tutors. This is convincingly reflected by the results of the lecture course "Differential diagnosis in general surgery". The good evaluation data on small group tutorials resulted largely from the "participation" and "discussion" scales, which represent interactivity in learning. CONCLUSION: The results of the present study suggest the importance of two major pedagogic ideas: continuity and didactic training of lecturers and tutors. These principles were widely implemented in Heicumed and have contributed to the success of the new curriculum.

["Multimedia symposium wares". An enrichment of medical and graduate education?]. / "Multimediale Symposiumsware". Eine Bereicherung der Aus- und Weiterbildung?

The continual development of the internet has supported the spread of surgical knowledge by electronic means. High quality products have to be offered from a software as well as a contents point of view. The question as to whether these new media and their contents have a real value for efficient and motivating use in medical education needed to be answered by first assessing a quality profile for the development of surgical educational modules which were then evaluated on the basis of so-called "symposia ware". First, the reactions and opinions of physicians at 47 universities were assessed by a standardized questionnaire concerning their demands on multimedia teaching/learning modules. Several different aspects of technique, content, presentation, didactics and background knowledge were analyzed. In a second step, their opinions were evaluated concerning two applications (symposia implemented on CD-ROM as a slideshow with original slides and audio) with surgical and gastroenterological contents by standardized questionnaire. Questions concerning personal background such as educational status and experience with computers, e-mail and the internet on one hand and the CD-ROM itself concerning content, relevance for daily clinical work and continuing medical education as well as the quality of the application on the other hand, were evaluated using marks (1 = best, 6 = worst). A total of 320 physicians participated in the first part of the interview. Of these, 93% were equipped with computers in hospital as well as privately. The Internet was used by 90% of them. The majority declined a full text presentation as well as the application of scroll fields. The participants rather favored the integration of text, pictures, animations and videos. Furthermore, 95% demanded the provision on the internet. Thirty-seven colleagues in their 5th (1-11) year of training were interviewed, and of those, 27 were working in a surgical department and 10 in a medical department. Individual computer knowledge was rated with a median of 3. This revealed that 60% were equipped with computers in hospital as well as at home, the remaining 40% had computers either in hospital or at home. All participants used the internet. In total, 57% had experience with "Symposia ware". The rating of the "Symposia ware" itself was positive. Relevance and applicability of a slideshow for imparting knowledge were rated with a median of 2. This showed that 81% would buy the CD-ROM in principle, and 89% would spent up to 50 EUR. Quality, language, content and user-friendliness were all rated 2. Physicians frequently use computers and the internet. All this indicates a high degree of acceptance of electronic teaching/learning modules in medical education. A uniform structure of contents as well as a platform-independent, web-based presentation is appreciated. To enhance illustration, a picture and video-oriented visualization should be chosen. Overall, "symposia ware" is rated positively. It should cost no more than 50 EUR and it represents a valuable source of information for physicians.

A new way for surgical education--development and evaluation of a computer-based training module.

Computer-based training (CBT) programs teach the material of a specific field and at the same time offer various ways of objectively assessing the knowledge gained. The interactive use of multi-media components such as text, graphics, animation, sound, digital slide shows, and videos as well as quizzes can theoretically facilitate the learning process. The aim of this study was the development and evaluation of a CBT-program by surgeons for student training. Using SuperCard, a teaching module for Distal Radius Fracture (DRF) was developed, which contains detailed clinical information. Video clips and vivid animations combine theoretical knowledge with practical experience. Fourth-year medical students (n = 103) were tested after using the module for 90 min. Other students (n = 47) served as the control group. In a 90 min lecture, DRF was discussed. CBT gained in all evaluated criteria (distinctiveness, detailed description, presentation of materials, structure, motivation for learning, time saved learning and memory retention) 15-20% better scores than the lecture. Although 82% of the students stated that their experience with computers was limited or insufficient, 100% found the use of CBT systems useful in student teaching. Most of them suggested the use of such programs as a method of exam preparation/self study (90%) or as a supplement to a lecture (40%). Based on these evaluations, CBT modules are an appropriate future teaching and learning system that is well accepted. In conclusion, the results of this study show that CBT-programs could be a valuable supplement to medical education. In addition, further development of CBT-programs and their use as information systems for surgical residency programs at universities can be suggested.

Renal arteries: optimization of three-dimensional gadolinium-enhanced MR angiography with bolus-timing-independent fast multiphase acquisition in a single breath hold.

PURPOSE: To compare two different three-dimensional (3D) gadolinium-enhanced magnetic resonance (MR) angiographic techniques. MATERIALS AND METHODS: In 26 patients suspected of having renal artery stenosis, results with fast multiphase 3D MR angiography were compared to those with standard 3D MR angiography in 37 patients. With both techniques, 31-second breath-hold acquisitions were performed. Multiphase angiography comprised five discrete 6.4-second acquisitions without bolus timing, and standard angiography comprised a single acquisition based on test-bolus timing. Two readers evaluated images obtained with both techniques in terms of image quality, artifacts, and vessel conspicuity. Accuracy of findings on the multiphase 3D MR angiograms for assessment of renal artery stenosis was determined by comparing them to digital subtraction angiograms and surgical findings. RESULTS: In the early arterial phase, multiphase 3D MR angiograms showed no image degradation by venous overlay, whereas standard 3D MR angiograms depicted at least minor overlay in 53 of 83 renal arteries (P < .001). Less parenchymal enhancement in the early arterial phase resulted in a higher vessel conspicuity for the divisions and segmental arteries (P < .001). Both readers detected and correctly graded 18 of 20 stenoses on the multiphase angiograms with almost perfect interobserver agreement (kappa > 0.89). CONCLUSION: Renal multiphase 3D MR angiography is an accurate technique requiring no bolus timing. The performance of early arterial phase imaging leads to improved depiction, particularly of the distal renovascular tree, compared to that with standard single-phase 3D MR angiography.

[MRI of the kidneys. New diagnostic strategies]. / MR-Bildgebung der Nieren. Neue Ansätze in der Diagnostik.

AIM: New diagnostic strategies for evaluation of the kidney by fast MR imaging techniques. MATERIAL AND METHODS: A comprehensive morphologic and functional evaluation of the kidney is proposed using fast MR imaging of renal morphology, multiphase 3D gadolinium MR angiography, MR urography and MR flow measurements. A single MR examination is designed to grade renovascular disease and assess the hemodynamic and functional significance, detect and characterize renal lesions and evaluate the urinary tract. RESULTS: The combined analysis of morphologic and functional data allows reliable assessment of renal artery stenosis, benign and malignant renal masses and diseases of the renal collecting system and ureters, as well as congenital abnormalities in good agreement to the results of conventional imaging modalities. The improved tissue contrast and additional functional information compensates for the disadvantage of a lower spatial resolution. CONCLUSION: Combined morphologic and functional MR examination represents a reliable, non-invasive and cost-effective alternative imaging modality for comprehensive diagnostic evaluation of renal disease.

Development of a computer based training program for liver transplantation.

The existence and future of every scientific area is directly and indirectly dependent on advanced education in that area and the quality of the work performed. Our aim in developing this program was to improve advanced education in liver transplant surgery and to ensure the quality of the work performed by every surgeon operating in this field. We developed a module that contains extensive information on the pathogenesis, symptoms, diagnosis, X-rays and treatment plans as well as operation-videos and case studies on the most common aspects in liver transplantation. This "teachware" is now on CD-ROM and can be installed on every personal computer without special computer knowledge. The expansion and updating of the material is technically facilitated with the help of an authoring tool.

Prevalence of enteropathogenic bacteria in surgically treated chronic inflammatory bowel disease.

BACKGROUND/AIMS: In order to assess the potential impact of bacterial eradication on recurrence rates, the prevalence of various enteropathogenic bacteria and toxins in chronic inflammatory bowel diseases (CIBD) was prospectively examined. METHODOLOGY: Stool, sera and gut tissue samples from a total of 59 patients (33 males, 26 females; mean age: 42 years +/- 14; 21 Crohn's disease, 14 ulcerative colitis, 24 controls) were examined for the presence of enteropathogenic bacteria by culture, immunoblotting and PCR. RESULTS: Conventional cultures failed to detect obligate pathogenic bacteria. By PCR, mycobacteria were found in 85% of all groups, with mycobacterium paratuberculosis not detected. Yersinia species were observed in 63% of patients with Crohn's disease, in 46% of patients with ulcerative colitis, and in 36% of the control patients. Pathogenic E. coli were identified in stool samples of three patients with ulcerative colitis (21%) by amplifying the EAE-gene, one of whom exhibited shiga-like-toxin as well. CONCLUSIONS: We concluded that mycobacteria do not play a causative role in CIBD. Yersinia species seem to persist in intestinal tissue in CIBD patients without adequate immune response and might, thus, contribute to tissue destruction. E. coli infections contribute to the disease process in a small group of patients with ulcerative colitis and their eradication might eliminate the need for immediate surgical intervention.

Pyruvate kinase and the interaction of amino acid and carbohydrate metabolism in solid tumors.

The interaction between glycolysis, glutaminolysis and tumor growth in WAG/Fra rnu/rnu rats has been investigated. Small tumors are characterized by a low conversion of glucose to lactate whereas the conversion of glutamine to lactate is high. In medium sized tumors the flow of glucose to lactate as well as oxygen utilization are increased whereas glutamine and serine consumption are reduced. At this stage the tumor cells start with glutamate and alanine production. Large tumors are characterized by a low oxygen and glucose supply but a high glucose and oxygen utilization rate. The conversion of glucose to glycine, alanine, glutamate, glutamine, and proline reaches high values and the amino acids are released. Pyruvate kinase increases with tumor weight and is positively correlated with an increase in glucose and oxygen utilization. The shift from glutamate consumption to glutamate production is correlated with an increase in glutamate dehydrogenase and glutamate oxaloacetate transaminase activity.

The partial gluteus maximus musculocutaneous turnover flap. An alternative concept for simultaneous reconstruction of combined defects of the posterior perineum/sacrum and the posterior vaginal wall.

Three cases with posterior perineo-sacral defects are presented. One is a 57-year-old white female following amputation of her rectum for carcinoma, radiation and chemotherapy with a significant residual sacral/perineal defect and loss of the posterior vaginal wall. The two other patients had radical pelvic exenteration after recurrent rectum carcinoma. A new myocutaneous turnover flap as a modification of the conventional gluteus maximus flap was designed to solve the particular reconstructive problems. The flap is based on branches of the inferior gluteal artery. The posterior cutaneous femoral nerve and the motor branches of the inferior gluteal nerve not leading into the muscle portion of the flap are left intact. The skin island can be used for vaginal reconstruction or can be de-epithelialised to fill perineal cavities. This new flap eventually enabled the successful reconstruction of the posterior vaginal wall and appropriate sacral/perineal soft tissue coverage in the first case. In the other patients the flap was used to achieve closure of the deep through-and-through defect acutely in one case, and after a 3-week interval in the other.