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.

P-074 BIOMECHANICALLY STABLE INCISIONAL HERNIA REPAIRS WITH DIS CLASS A MESHES ARE DURABLE AFTER A 3 YEAR FOLLOW UP

Aim

Hernia meshes can be classified according to the tackiness towards cyclic load. Meshes with the best adhesiveness are named DIS class A. Are reconstructions with these meshes durable after 3 years?

Material and methods

Biomechanical principles of the reconstruction of the abdominal wall were analyzed ex vivo with cyclic loading common in material sciences. The resulting GRIP concept was clinically applied. The patients were followed in yearly intervals.

Results

A total of 129 patients (68 males and 61 females) were followed for 3 years after treatment for 93 primary and 36 recurrent incisional hernia. Progrip® was used in 53 cases (P), Dahlhausen® Cicat in 76 cases (C). P was used for smaller hernia with lower overlap due to the higher tackiness. Hernia sizes treated with C were significantly larger (u-test: p > 0.001). The mesh-defect area ratio was higher with P compared with C (11.9 vs 5.8). Fixation requirements were lower with 8 points for P and 80 points for C to reach adequate GRIP levels. GRIP was twice that minimally required. Larger hernia took longer OR times (median P: 104 vs. median C: 183 min; p > 0.001). Larger hernias were associated with more postoperative minor complications (6–14%, 1 re-operation for seroma). Length of stay was comparable with 5–6 days. During follow up, no recurrence was detected. Pain levels were low (median NAS = 0 after 3 years; u-test: p = 0.07672).

Conclusion

Incisional hernia can be repaired safely and durably based on biomechanical principles.

P-075 DURABLE REPAIR OF INCISIONAL HERNIA BASED ON BIOMECHANICAL PRINCIPLES – 3 YEAR FOLLOW UP

Aim

Durable composite constructions of polymers follow specific mechanical principles. Incisional hernia can be repaired durably based on biomechanical principles. How are the results after three years?

Material and methods

The biomechanics of the abdominal wall was analyzed ex vivo with cyclic loading common in material sciences. The resulting GRIP concept was clinically applied. The tissue quality of the individual patient was assessed with computed tomography at rest and during Valsalva's maneuver. All patients recieved single-shot antibiosis. Patients were discharged after full ambulation was achieved.

Results

A total of 228 patients (120 males and 108 females) were treated for incisional hernia. Primary hernia was repaired in 166, recurrence in 62 patients. The patients had an average of 1.3 risk factors with most patients grouped as ASA III (n= 119). Emergency repairs were necessary in 11 patients. Hernia orifices were mostly median (N= 141) and lateral (63 patients) with 23 combined cases. Hernia sizes were on average 9 ± 6 cm wide and 13 ± 8 cm long. The mesh-defect area ratio was 7.75. Fixation was necessary with a median of 60 fixation points to reach adequate GRIP levels. A total of 137 patients were followed for three years so far. Four patients died during follow-up (Follow-up rate 100%). One recurrence was detected in a liver transplant patient reconstructed with a sandwich. Pain levels were low (median NAS = 0 at rest and under load, u-test: p = 0.07672).

Conclusion

Incisional hernia can be repaired durably based on biomechanical principles.

OC-089 STANDARDIZED SUTURING OF MEDIAN INCISIONS AND DEFECTS CAN REDUCE SUTURE SLACKENING AND BURST RATES

Aim

Has standardization of criteria of a small-stitch-small-bite suture (SSSB) a significant influence on its durability?

Material and Methods

Porcine abdominal walls and bovine flanks were used as model tissues. We cut a median 15 cm long incision into the tissues. Then we punched an additional round (5–10 cm wide) or rhomboid (5×15 cm) defect in the middle of the incision. Monomax® and Maxon® USP 1 and 2–0 sutures were used in a running technique with a suture to incison lengths above 4:1. The mesh-tissue compounds were investigated on our self-built hydraulic bench test simulating coughs. Cyclic pressure impacts were repeatedly delivered peaking around 210 mmHg. In each of twenty experimental series, ten preparations were loaded 425 times.

Results

Standardized SSSB sutures using 2–0 Monomax® with a suture-incision-ratio of 4.5 : 1 can give a durable closure of a large defect in thin, elastic tissues. Under other conditions, suture lines can reopen. Standardization of the suturing technique significantly increased the durability (p = 0.00008). Defect shape is important since the larger rhomboid defects were easier to close compared to the smaller, 5 cm wide, round defects (SSSB: p = 0.00018; LSLB: p = 0.00906).

Discussion

After standardization, insignificant influences on the durability were exerted by the suture material and diameter, the bite and stitch size (small versus large), the surgeon, the tissue elasticity and tension and the defect size.

Conclusions

A standardized suturing technique was developed. The standardization improved the durability of a suture repair significantly.

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.

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 der traditionellen studentischen Ausbildung in der Chirurgie

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?]

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.

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.

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]

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.

[Computer-based training exemplified by the carotid artery]

The purpose of computer-based training (CBT) is interactive use of multimedia components, such as text, graphics, animation, sound, digital slide shows, and videos. This CD-ROM illuminates different aspects of carotid surgery: cerebrovascular insufficiency, sonographic and neuroradiological diagnostics, indications and results of carotid surgery in the literature, perioperative complications and new developments such as interventional procedures. Digital imaging (60 minutes of video sequences and 250 graphics) especially focus on operative standard procedures (conventional and eversion technique) and alternative methods. CBT is an evolving supplement to improve education programs in vascular surgery.

[Multi-media CD-ROM: a new medium for improving information dissemination]

New media can be used in medicine for effective and prompt imparting of knowledge. We present a multimedia CD-ROM providing up to date congress information.

[Development of a multimedia CD-ROM series for improving surgical education and continuing education]

In the past 4 years, the computer-based training laboratory of the Department of Surgery, University of Heidelberg, has developed a multimedia library, the med.LIVE-series. This CD-ROM series contains 5000 multimedia units with information of a uniform structure that comprises 26 CD-ROMs. These modules contribute significantly to the training and education of medical students and doctors. Furthermore, this multimedia library is intended to aid in the development of a database-supported online information system. Authors interested are encouraged to contribute to the series.

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.

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.

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.

[Detection of the hemodynamic effects of renal artery stenosis with MRI flow measurement]

Data derived from the MR-CINE phase-contrast flow measurement of renal arteries correlates well with the angiographically detected degree of stenosis and scintigraphic measurements. MR data permit the quantitative analysis of altered hemodynamics and MR is a non-invasive substitute for angiography preoperatively and during follow-up. Angiography is indicated only for the evaluation of morphological criteria.

[Development of a computer-assisted learning program for liver transplantation]

The German Society for Surgery recently decided to rename the "video library" as a "multimedia library", which will include also interactive, nonlinear computerised teachware in surgery. We report on the complex interaction of authors, editor, and the computer-based training laboratory, and the pitfalls with respect to data collection, structure, implementation, and technical aspects of the CD-ROM liver transplantation.

[Classification of hemodynamic changes in renal artery stenosis using cine magnetic resonance phase contrast flow measurements]

PURPOSE

To evaluate the use of high-temporal resolution cine MR phase-contrast flow measurements for assessment of flow dynamics in renal artery stenosis (RAS).

MATERIAL AND METHODS

In a dog model, cine MR flow measurements were validated by comparing the MR flow data to an invasive transit-time ultrasound reference technique for different degrees of RAS. Cardiac-gated MR flow curves were recorded in 56 renal arteries of 28 patients with a temporal resolution of at least 32 ms. In all cases RAS was confirmed by digital subtraction angiography (DSA). Abnormalities of flow dynamics were assessed in the calculated flow curves using the MR parameters mean flow, maximum velocity, and time to systolic maximum.

RESULTS

By means of the MR blood flow parameters high-grade stenoses (> 50%, n = 23) were detected with sensitivity of 100% and specificity of 94% with reference to DSA. The overall differentiation between stenoses (n = 37) and non-stenosed vessels (n = 19) revealed a sensitivity of 87% and a specificity of 100%.

CONCLUSION

Analysis of cardiac-gated MR flow curves provides a non-invasive method to assess the hemodynamic significance of RAS and thus allows a functional evaluation in relation to the morphologic characteristics of the stenosis.

[Computer-based training--a new method in surgical education and continuing education]

Computer-based training (CBT) programs teach the material of a specific field and at the same time offer various ways of objectively checking the knowledge gained. The interactive use of multimedia components, such as text, graphics, animation, sound, digital slide shows, videos and quizzes, facilitates the learning process. The aim of this study was the development and evaluation of a CBT program for use by surgeons teaching students. Using SuperCard, a teaching module for distal radius fracture (DRF) was developed, containing detailed clinical information. Video clips and vivid animation 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. In all evaluated criteria (distinctness, detailed description, presentation of materials, structure, motivation to learn, time saved while learning and memory retention), CBT gained 15-20% better scores than the lecture. Although 87% of the students stated that their experience with computers was limited or insufficient, 100% found the use of CBT systems helpful in student teaching. Most of them suggested the use of such programs as a exam preparation/self study method (90%) or as a supplement to a lecture (40%). Based on these evaluations, it is clear that CBT modules are an appropriate future teaching and learning system that will be well accepted. In conclusion, CBT programs should be integrated into medical education as a valuable supplement. With this aim, CBT systems should be developed and used at universities as an information system for the surgical residency program.

Renal artery stenosis: grading of hemodynamic changes with cine phase-contrast MR blood flow measurements

PURPOSE

To analyze the blood flow dynamics in renal artery stenosis with high-temporal-resolution cine phase-contrast magnetic resonance (MR) flow measurements.

MATERIALS AND METHODS

Cine phase-contrast MR flow measurements were invasively validated with real-time intraoperative transit-time ultrasound (US). In 23 patients, 48 renal artery stenoses were confirmed at digital subtraction angiography. Cardiac-gated cine phase-contrast MR flow measurements were obtained in 32-msec intervals, and flow curves were calculated for the whole cardiac cycle. Hemodynamic parameters evaluated included the decrease in mean flow and the delay and reduction in the systolic velocity maximum due to decrease in or absence of the early systolic peak.

RESULTS

Overall differentiation between renal artery stenosis (n = 31) and nonstenosed vessels (n = 17) with cine phase-contrast MR revealed a sensitivity of 90% and specificity of 94% compared with findings at digital subtraction angiography. High-grade stenoses (>50%, n = 19) were detected with cine phase-contrast MR with sensitivity of 100% and specificity of 93%.

CONCLUSION

Quantitative and qualitative analysis of cardiac-gated cine phase-contrast MR flow velocity curves provided a highly accurate method to detect hemodynamic abnormalities in patients with suspected renal artery stenosis.

Morphometry and classification in abdominal aortic aneurysms: patient selection for endovascular and open surgery

PURPOSE

To evaluate the anatomic morphology of abdominal aortic aneurysms (AAAs) and compose a classification system to facilitate patient selection for endovascular graft (EVG) repair.

METHODS

Data on 242 consecutive AAA patients evaluated on a nonemergent basis in a 3.5-year period to July 1996 were prospectively entered into a registry. Patients were examined using sequential intravenous spiral computed tomographic angiography and intraarterial digital subtraction angiography. The data collected and analyzed included: diameters of the supra- and infrarenal aorta, aneurysm, aortoiliac bifurcation, and iliac arteries; lengths of the proximal neck, distal cuff, and aneurysm; degrees of iliac artery tortuosity; and occlusion of the visceral, renal, or iliac arteries.

RESULTS

The 242 aneurysms could be easily grouped into three distinctive categories related to the extent of the aneurysmal disease. Type I AAAs (11.2%) had nondilated, thrombus-free infrarenal (15 mm) necks and distal (10 mm) cuffs appropriate for EVG anchoring. In type II and its subgroups (72.3%), a sufficient proximal neck was present, but the aneurysm extended into the iliac arteries; 56% of these were eligible for a bifurcated endograft. In type III (16.5%), a sufficient proximal neck was missing, independent of distal involvement. In all, 51.7% were good EVG candidates based on AAA morphology. Taking into consideration relevant concomitant vascular diseases, proximal iliac kinking, and iliac, renal, or visceral occlusive disease, only 30.2% of the population were potential candidates for an efficient and secure EVG repair using the devices currently available.

CONCLUSIONS

In contrast to classical open repair, detailed preoperative measurements are recommended for EVG planning. The use of liberal EVG indications may lead to a higher incidence of complications, whereas restrictive morphology-based selection criteria may offer excellent results.

Association of resistance-related protein expression with poor vascularization and low levels of oxygen in human rectal cancer

Rectal carcinomas of previously untreated patients were analyzed for oxygen status using a computerized polarographic needle electrode histograph. Microvessel density and expression of c-jun, vascular endothelial growth factor (VEGF) and several resistance-related proteins (glutathione S-transferase-pi, GST; thymidylate synthase, TS; metallothioneine, MT) were determined using immunohistochemistry. To examine whether a relationship exists between intratumoral vessel density and tumor oxygenation, microvessel counts were determined in a 400x field using factor-VIII-related antigen and were correlated with the corresponding pO2 values. Linear regression analysis revealed a significant relationship between vessel density and oxygenation status of the tumors. Expression of c-jun, VEGF and resistance-related proteins was correlated with microvessel counts and pO2 values. Significantly lower vessel counts were found in GST- and MT-positive tumors and in tumors with overexpression of c-jun and VEGF than in negative tumors. In addition, significantly lower pO2 values were found in c-jun- and VEGF-positive tumors as well as a tendency for pO2 values to be lower in tumors where MT, GST and TS were expressed. These data show that expression of c-jun, VEGF, and resistance-related proteins is linked with poor vascularization and low oxygenation status in rectal cancer.

Association of resistance-related protein expression with poor vascularization and low levels of oxygen in human rectal cancer

Rectal carcinomas of previously untreated patients were analyzed for oxygen status using a computerized polarographic needle electrode histograph. Microvessel density and expression of c-jun, vascular endothelial growth factor (VEGF) and several resistance-related proteins (glutathione S-transferase-pi, GST; thymidylate synthase, TS; metallothioneine, MT) were determined using immunohistochemistry. To examine whether a relationship exists between intratumoral vessel density and tumor oxygenation, microvessel counts were determined in a 400x field using factor-VIII-related antigen and were correlated with the corresponding pO2 values. Linear regression analysis revealed a significant relationship between vessel density and oxygenation status of the tumors. Expression of c-jun, VEGF and resistance-related proteins was correlated with microvessel counts and pO2 values. Significantly lower vessel counts were found in GST- and MT-positive tumors and in tumors with overexpression of c-jun and VEGF than in negative tumors. In addition, significantly lower pO2 values were found in c-jun- and VEGF-positive tumors as well as a tendency for pO2 values to be lower in tumors where MT, GST and TS were expressed. These data show that expression of c-jun, VEGF, and resistance-related proteins is linked with poor vascularization and low oxygenation status in rectal cancer.

Oxygenation of dog liver transplants as an early indicator of graft failure

This study examines the potential value of liver oxygenation as a predictor of early graft function. pO2 measurements were performed on 10 pairs of beagle (donor) and foxhound (recipient) dogs during pentobarbital anesthesis. Two different explantation techniques were used: complete preparation and dissection before perfusion and explantation (group A) or rapid perfusion and explantation with detailed preparation of the liver and dissection of vessels ex situ after explantation (group B). In both groups, the technique of liver perfusion with 1,000 ml arterial and 500 ml portovenous application of ice-cold UW solution was equal. Local oxygen partial pressure values were obtained polarographically with miniaturized needle electrodes. The liver oxygenation directly after laparotomy was comparable in both groups (median values around 54 mm Hg). Prior to the infusion of UW solution, a reduction of the tissue oxygenation values to 24 mm Hg was observed in group A (p < 0.01 compared to postlaparotomy values). In group B, limited preexplantation surgical dissection resulted in a reduced pO2 decline to 42 mm Hg (n.s.). After transplantation, the reduced tissue oxygenation persisted in the livers of the dogs which were completely dissected in situ (group B) as compared to the preexplantation recipient and the donor liver before instrumentation (p < 0.01). In contrast, rapidly perfused livers again exhibited only an insignificant reduction of tissue oxygenation following transplantation. Survival correlated linearly with the liver oxygenation within the observation time after transplantation (p < 0.01). A significant survival advantage was found for the rapid perfusion technique (p < 0.05). We conclude that the tissue oxygenation might provide valuable information on early graft function.

[Prospective preoperative morphometry of abdominal aortic aneurysms: selective patient management for endovascular surgery]

The objective of this prospective clinical investigation of 205 elective abdominal aortic aneurysm (AAA) patients over a 3-year period. 1993-1995, was both to evaluate the morphology and aortic dimensions of AAA as a management decision for patient selection for endovascular grafting and to correctly plan the custom-made TPEG size and shape prior to the procedure.

[Infrarenal abdominal aortic aneurysm: morphological classification as decision aid for therapeutic procedures]

This clinical trial aimed to prospectively investigate the morphological structure of infrarenal abdominal aortic aneurysms (AAA) to establish a valid dataset in the preoperative assessment supporting either the conventional or endovascular (TPEG) surgical approach. Regarding both the general feasibility testing and safe TPEG placing, all the anatomic AAA data must already be measured preprocedurally, due to the necessity for conversion as a frequent consequence of an intraprocedural failure. Between January 1993 and June 1995, all the patients (n = 159) admitted for elective AAA repair, were prospectively analysed. Graded on the basis of these measurements we developed a new AAA classification system supporting the kind of the surgical procedure (standard) approach vs. TPEG). Three different types of AAA were clearly defined. Due to morphological AAA criteria, 86 out of 159 patients (54.1%) might be suitable for TPEG (Type I, IIA and IIB). An infrarenal (proximal) neck < 15 mm, an infrarenal aortic diameter > 24 mm or an extension of the aneurysm to the iliac bifurcation are considered to be exclusion criteria for TPEG placement. In consideration of relevant co-morbidities (e.g. renal artery stenosis, SMA occlusion, iliac occlusive disease, simultaneous operations) only 43 out 159 patients (27.1%) were good candidates for TPEG. In general, smaller AAA are more appropriate for TPEG repair due to better proximal and distal fixation. As a consequence, indication criteria for AAA repair must not be expanded to smaller AAA.

Microsurgical neck dissection for metastasizing medullary thyroid carcinoma

Surgery is the only accepted method for a potentially curative treatment of metastatic medullary cancer of the thyroid (MCT). Between 5/1988 and 2/94 53 patients (mean age 43, 14-65 years) were treated. A total of 24 patients underwent surgery of both sides of the neck whereas 29 patients required only one side. Six months after surgery, a profound reduction in basal serum calcitonin levels (CT) was detected in all patients. Upon pentagastrin stimulation, CT levels remained suppressed in eight patients. A pathological increase of normalized basal CT values was noted in 33 patients. In 12 patients, basal CT concentrations remained elevated after surgery. We conclude that metastatic MCT can be effectively treated by microsurgical modified radical neck dissection.

Intraoperative radiotherapy for primary and recurrent rectal cancer

A total of 40 primary and 20 recurrent adenocarcinomas of the rectum were treated. Intraoperative radiation therapy was combined with pre- or postoperative irradiation and 5-FU and leucovorin treatment. An abdomino-perineal excision was performed in 32 and an anterior resection in 26 cases. A Hartmann's procedure was performed in two patients. Forty-two tumours were completely resected. Residual disease was microscopically detectable in 10 cases. In eight patients, tumour residual was evident macroscopically. Postoperatively, wound infection was observed in six and anastomotic dehiscence in four cases. After a follow-up of 20 months, 46 patients revealed no evidence of disease. Local recurrences and distant metastases were detected in two patients each. Ten patients died of their disease.

[Intraoperative radiotherapy of locally advanced and recurrent rectal cancer]

Intraoperative radiotherapy (IORT) offers a technique to increase radiation dose to the residual tumor or tumor bed while sparing neighboring radiosensitive organs. Beyond the mostly employed dedicated electron beam facilities, the afterloading--'flab'-technique was also used. In first prospective studies IORT was performed in patients with not completely resected locally advanced (T4) or recurrent tumors after complete external beam radiotherapy (50.4 Gy) as an additional boost dose, using small field sizes. This locally restricted dose escalation yielded higher local control and an increased prognosis. Nerves and ureters were dose limited. In our series IORT was performed for rectal carcinomas stages II and III. After an external beam radio- or radio-chemotherapy with 41.4 Gy, shrinking field boost irradiation was done intraoperatively with moderate doses and larger IORT field sizes. Compared to a historical control with high-dose external beam radiotherapy alone local control rate was increased. Radiogenic neuropathy or stenosis of the ureter was not observed. The impact on prognosis must awaited. Randomized studies are required to clearly describe the role of IORT in rectal carcinoma.

Microsurgical neck dissection for occultly metastasizing medullary thyroid carcinoma. Three-year results

BACKGROUND

Medullary thyroid carcinoma (MTC) metastasizes early into the regional lymph nodes, but distant metastases occur late. Modified radical neck dissection might improve the treatment results for occultly metastasizing MTC.

METHODS

The authors report 23 patients after a minimal follow-up of 2 years (median, 36 months). There were 11 female and 12 male patients. The mean age was 43 years (+/- 13 years). The surgical technique included the meticulous dissection of all compartments of the neck, resulting in a unilateral or bilateral modified radical neck dissection with the complete removal of the lymphatic and fatty tissue between important anatomical structures. The surgical boundaries extended cranially to the mastoid, caudally to the brachiocephalic vein involving a transcervical mediastinal dissection, and laterally to the edge of the trapezoid muscle. Ten patients were treated bilaterally and 13 patients unilaterally.

RESULTS

The basal calcitonin values of 18 of the 23 patients were postoperatively normalized with 4 patients having normal basal and pentagastrin-stimulated calcitonin levels. Five patients with persistently elevated basal serum calcitonin values had a marked reduction of the postoperative calcitonin levels compared with their preoperative concentrations. However, in these five patients histologic abnormalities precluded a surgical cure. The permanent complication rates were tolerable (4 of 33 neck dissections).

CONCLUSIONS

The microsurgically extended neck dissection can reduce basal and pentagastrin-stimulated serum calcitonin values to normal levels even after long intervals following primary thyroidectomy.

Medullary carcinoma of the thyroid--therapeutic strategy derived from fifteen years of experience

BACKGROUND

The purpose of this investigation was to analyze our experience with patients treated for medullary carcinoma of the thyroid to identify prognostic factors and to develop a stage-related treatment strategy that might improve cure rates.

METHODS

Between 1970 and 1985 a total of 40 patients with medullary thyroid carcinoma were treated (21 women, 19 men; mean age +/- SEM; 40 +/- 3 years; mean follow-up, 82 +/- 12 months). Initial operation involved total thyroidectomy (28 patients), subtotal resection (11 patients), and a lobectomy (1 patient). The initial lymph node dissection generally consisted of a selective removal of enlarged nodes. Unilateral neck dissection was performed in six cases. Secondary operation for recurrent disease was necessary in 26 patients.

RESULTS

At the end of the follow-up period 10 patients were tumor free, 12 patients were scheduled for further treatment, six patients suffered from persistent but clinically occult disease, and 12 patients had died (mean survival time, 68 +/- 7 months). The paramount prognostic factor was the absence or presence of lymph node involvement at the time of primary operation (p = 0.011). Patients with distant metastases died within 2 years of diagnosis. Women, patients younger than 40 years of age, and those elicited by familial screening programs exhibited increased survival times.

CONCLUSIONS

Because of the prognostic and therapeutic importance we recommend the total thyroidectomy with a complete dissection of the central lymph node compartment as primary treatment. Patients with lymph node involvement or elevated serum calcitonin levels should subsequently be treated by a modified radical neck dissection of the lateral compartments.

[The value of clinical, laboratory and sonographic findings in acute appendicitis--effect of surgical experience and bacteriologic diagnosis on the rate of wound healing disorders]

A total of 361 patients were admitted to the Department of Surgery of the University of Heidelberg between January 1989 and April 1990 for acute appendicitis. Neither the physical examination nor laboratory results were unequivocally diagnostic in a third of the patients. The ultrasonographic visualization of the inflamed appendix could confirm the diagnosis in 50% of the clinically doubtful cases (predictive value: 84%). Further diagnostic procedures were rarely necessary. The perforation rate was independent of the duration of the preoperative hospitalization due to the rapid surgical treatment. Contrary to previous reports, the likelihood of an intraoperatively innocent appendix increased with delayed surgery. Wound infection rates were similar after appendectomies by surgeons in training and by fully qualified surgeons although perforated appendices were typically removed by the latter ones. Antibiotic therapy was usually administered for severely inflamed appendices depending on the intraoperative findings and for perforated appendices and reduced the rate of wound infections if more than two bacteria had been cultured from a routine intraoperative swab. The documentation used in Baden-Württemberg for quality control should include the result of an intraoperative appendiceal swab.

Microsurgical lymph node dissection for metastatic asymptomatic C-cell carcinoma

In persistent, clinically inapparent medullary thyroid carcinoma, microsurgical dissection of all lymph node compartments of the neck was performed. Between August 1988 and September 1991, 28 cases (mean age 43.3 years) were treated with 38 surgical interventions. Twenty patients had the sporadic form and eight patients the familial form. Unilateral neck dissection resulted in normalization of serum calcitonin (CT) levels even after pentagastrin stimulation in two patients whereas 16 patients exhibited abnormal CT stimulation tests. Eight of ten patients who had bilateral neck dissections had positive pentagastrin test results after surgery. The main postoperative complications included loss of local cutaneous sensation, generally temporary, and unilateral recurrent laryngeal nerve paralysis.