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.

Regulation of hematopoiesis in rats exposed to antiorthostatic, hypokinetic/hypodynamia: I. Model description.

This paper provides baseline information regarding the regulation of hematopoiesis in antiorthostatic, hypokinetic/hypodynamic ("suspended") laboratory rats. The object of the study was to compare the hematological effects of suspension with those seen following space flight in man and/or rats. Observed in man after exposure to microgravity and in the suspended rats was a reduced red blood cell mass, suppressed erythropoiesis, a transient increase in hematocrit due to a reduction in plasma volume, a post-exposure hematocrit decrease, a weight loss (or failure to thrive) and a reduction in food and water consumption. A rightward shift in the oxyhemoglobin dissociation curve, observed in the rat "model", has been predicted to occur during manned space flight but has not yet been measured. Suppression of hematopoiesis is a common feature of rats during both space flight and suspension. Platelet counts showed no significant change in rats after suspension or in man during space flight. Unlike man in space but similar to space flight-exposed rats, no significant change in leukocyte number or reactivity to PHA in vitro, or in red blood cell shape distribution were observed in the suspended rats. At least in a gross sense, the rat "model" seems to reproduce many of the known hematological effects of space flight and offers promise as a 1 X g analog for understanding hematopoietic effects similar to those found in space flight.