Ultrasound shear wave elastography effectively predicts integrity of ventral hernia repair using acellular dermal matrix augmented with platelet-rich plasma (PRP).

BACKGROUND: Complications of ventral hernia repair (VHR) may be investigated by computed tomography or ultrasound (US) but neither modality gives a quantifiable metric of repair quality short of identifying hernia recurrence. Platelet-rich plasma (PRP), a growth factor-rich autologous blood product, has been shown to improve incorporation of native tissue with bioprosthetics. In this study, we investigate the effect of PRP on the incorporation and mechanical integrity of a non-crosslinked porcine acellular dermal matrix (pADM) in a rodent model of VHR and the correlative ability of ultrasound shear wave elastography (US-SWE) to assess repair quality. METHODS: PRP was isolated from whole blood of Lewis rats. Twenty-eight Lewis rats underwent chronic VHR using either pADM alone or augmented with autologous PRP prior to non-invasive imaging assessment and specimen harvest at either 3 or 6 months. US-SWE was performed to estimate the Young's modulus prior to histological assessment and data from PRP-treated rodents were compared to controls. RESULTS: Implanted pADM was easily distinguishable by US-SWE imaging in all cases analyzed in this study. The mean Young's modulus measured was 1.78 times and 2.54 times higher in PRP-treated samples versus control at 3-month and 6-month time points respectively (p < 0.05). At 3 months, qualitative and quantitative histology revealed decreased inflammation and improved incorporation in PRP-treated samples along the implant/abdominal wall interface. At 6 months, the PRP cohort had no hernia recurrence and preserved ADM integrity from immunologic degradation, while all control animals suffered hernia recurrence (4/6) or extreme ADM thinning (2/6). CONCLUSION: This study confirms both the efficacy of PRP in augmenting VHR using pADM, as well as the reliability of US-SWE to non-invasively predict the quality of VHR. Although further human studies are necessary, this work supports PRP use to improve VHR outcomes and US-SWE potential for bedside non-invasive hernia characterization.

Comparison of Radiation Exposure from Fixed Table Fluoroscopy to a Portable C-Arm During Ureteroscopy.

INTRODUCTION: Current treatment practices within the field of endourology require the routine use of radiation exposure to provide adequate imaging during urologic procedures. One such procedure requiring repeated radiation exposure during treatment is ureteroscopy. We set out to compare estimated fluoroscopic radiation exposures employing fixed table and portable C-arm fluoroscopy. MATERIALS AND METHODS: A cross-sectional dosimetry phantom model was placed supine on both fixed fluoroscopy and standard operating room tables. The models were then exposed to three separate 5-minute runs of fluoroscopic exposure. Metal oxide semiconductor field effect transistor dosimeters were utilized in organ-specific locations to determine specific radiation exposure dosages. Absorbed radiation was determined for each organ location for both fluoroscopy units. Organ dose volumetric corrections were performed for skin and red bone marrow, to correct for the nonirradiated portion. Organ dose rate (ODR, mGy/s) and effective dose rate (EDR, mSv/s) were calculated, with values reported as mean ± standard deviation. RESULTS: There were found to be statistically significant elevations for both total EDR and organ-specific dose rates with the use of fixed table fluoroscopy compared with C-arm fluoroscopy. EDR was found to be 0.0240 ± 0.0019 mSv/s for the fixed table unit and 0.0029 ± 0.0005 mSv/s for the C-arm unit (p = 0.0024). Internal organs exposed to the most radiation during fixed table fluoroscopy included the gall bladder and stomach in comparison to C-arm fluoroscopy, which found elevated exposure in the kidneys, pancreas, and spleen. CONCLUSION: The routine use of fixed table fluoroscopy results in significantly elevated estimated organ doses and EDR when directly compared with C-arm fluoroscopy in model trials. This difference should be taken into consideration by practicing urologists when patient treatment requires the use of fluoroscopy to maintain radiation exposure as low as reasonably achievable.

Characterization of ventral incisional hernia and repair using shear wave elastography.

BACKGROUND: To assess the integrity of hernia repair, imaging modalities such as computed tomography or ultrasound (US) are commonly used. Neither modality has currently the capacity to simultaneously image the mesh and quantify a prosthetic and surrounding tissue stiffness. In this pilot study, we hypothesize that US shear wave elastography (SWE) can be used to identify a polyester mesh and a biologic graft and to assess their stiffness noninvasively in a rat model of bridging hernia repair. METHODS: Lewis rats underwent hernia creation and repair with Parietex or Strattice at 30 d. After 3 mo, the animals were euthanized, and the Young's Modulus was measured using SWE. Three-dimensional reconstructions of the hernia pre- and post-repair were performed using in-house image processing algorithms. RESULTS: SWE was capable of accurate and real-time assessment and diagnosis of the hernia defects in vivo. Young's Modulus of Parietex meshes and Strattice grafts as estimated from the shear wave elastograms were found to be statistically different from each other (P < 0.05). Accurate three-dimensional reconstructions of the hernia defects pre- and post-repair were generated. CONCLUSIONS: In this study, we demonstrate the feasibility of using US SWE to detect ventral hernias and evaluate mesh repair in vivo. Our results indicate that the presence of a hernia and repair can be reliably visualized by SWE and three dimensionally reconstructed. Thus, this technique may provide both structural and functional information regarding the hernia and the repair.

Biomimetic collagen/elastin meshes for ventral hernia repair in a rat model.

Ventral hernia repair remains a major clinical need. Herein, we formulated a type I collagen/elastin crosslinked blend (CollE) for the fabrication of biomimetic meshes for ventral hernia repair. To evaluate the effect of architecture on the performance of the implants, CollE was formulated both as flat sheets (CollE Sheets) and porous scaffolds (CollE Scaffolds). The morphology, hydrophylicity and in vitro degradation were assessed by SEM, water contact angle and differential scanning calorimetry, respectively. The stiffness of the meshes was determined using a constant stretch rate uniaxial tensile test, and compared to that of native tissue. CollE Sheets and Scaffolds were tested in vitro with human bone marrow-derived mesenchymal stem cells (h-BM-MSC), and finally implanted in a rat ventral hernia model. Neovascularization and tissue regeneration within the implants was evaluated at 6weeks, by histology, immunofluorescence, and q-PCR. It was found that CollE Sheets and Scaffolds were not only biomechanically sturdy enough to provide immediate repair of the hernia defect, but also promoted tissue restoration in only 6weeks. In fact, the presence of elastin enhanced the neovascularization in both sheets and scaffolds. Overall, CollE Scaffolds displayed mechanical properties more closely resembling those of native tissue, and induced higher gene expression of the entire marker genes tested, associated with de novo matrix deposition, angiogenesis, adipogenesis and skeletal muscles, compared to CollE Sheets. Altogether, this data suggests that the improved mechanical properties and bioactivity of CollE Sheets and Scaffolds make them valuable candidates for applications of ventral hernia repair. STATEMENT OF SIGNIFICANCE: Due to the elevated annual number of ventral hernia repair in the US, the lack of successful grafts, the design of innovative biomimetic meshes has become a prime focus in tissue engineering, to promote the repair of the abdominal wall, avoid recurrence. Our meshes (CollE Sheets and Scaffolds) not only showed promising mechanical performance, but also allowed for an efficient neovascularization, resulting in new adipose and muscle tissue formation within the implant, in only 6weeks. In addition, our meshes allowed for the use of the same surgical procedure utilized in clinical practice, with the commercially available grafts. This study represents a significant step in the design of bioactive acellular off-the-shelf biomimetic meshes for ventral hernia repair.

Platelet-rich plasma: a biomimetic approach to enhancement of surgical wound healing.

Platelets are small anucleate cytoplasmic cell bodies released by megakaryocytes in response to various physiologic triggers. Traditionally thought to be solely involved in the mechanisms of hemostasis, platelets have gained much attention due to their involvement wound healing, immunomodulation, and antiseptic properties. As the field of surgery continues to evolve so does the need for therapies to aid in treating the increasingly complex patients seen. With over 14 million obstetric, musculoskeletal, and urological and gastrointestinal surgeries performed annually, the healing of surgical wounds continues to be of upmost importance to the surgeon and patient. Platelet-rich plasma, or platelet concentrate, has emerged as a possible adjuvant therapy to aid in the healing of surgical wounds and injuries. In this review, we will discuss the wound healing properties of platelet-rich plasma and various surgical applications.

Radiation Dosimetry for Ureteroscopy Patients: A Phantom Study Comparing the Standard and Obese Patient Models.

PURPOSE: To determine the effect of obesity on radiation exposure during simulated ureteroscopy. METHODS: A validated anthropomorphic adult male phantom with a body mass index (BMI) of approximately 24 kg/m(2), was positioned to simulate ureteroscopy. Padding with radiographic characteristics of human fat was placed around the phantom to create an obese model with BMI of 30 kg/m(2). Metal oxide semiconductor field effect transistor (MOSFET) dosimeters were placed at 20 organ locations in both models to measure organ dosages. A portable C-arm was used to provide fluoroscopic x-ray radiation to simulate ureteroscopy. Organ dose rates were calculated by dividing organ dose by fluoroscopy time. Effective dose rate (EDR, mSv/sec) was calculated as the sum of organ dose rates multiplied by corresponding ICRP 103 tissue weighting factors. RESULTS: The mean EDR was significantly increased during left ureteroscopy in the obese model at 0.0092 ± 0.0004 mSv/sec compared with 0.0041 ± 0.0003 mSv/sec in the nonobese model (P < 0.01), as well as during right ureteroscopy at 0.0061 ± 0.0002 and 0.0036 ± 0.0007 mSv/sec in the obese and nonobese model, respectively (P < 0.01). EDR during left ureteroscopy was significantly greater than right ureteroscopy in the obese model (P = 0.02). CONCLUSIONS: Fluoroscopy during ureteroscopy contributes to the overall radiation dose for patients being treated for nephrolithiasis. Obese patients are at even higher risk because of increased exposure rates during fluoroscopy. Every effort should be made to minimize the amount of fluoroscopy used during ureteroscopy, especially with obese patients.

Evaluation of Novel Ball-Tip Holmium Laser Fiber: Impact on Ureteroscope Performance and Fragmentation Efficiency.

PURPOSE: A novel ball tip (BT) holmium laser fiber has recently been developed, which features a modified rounded tip. The modification is purported to aid in insertion and minimize damage to the ureteroscope working channel. We evaluated this laser fiber with regard to stone comminution, tip degradation, insertional force into the ureteroscope, and impact on ureteroscope deflection. MATERIALS AND METHODS: A 242 µm BT fiber and a standard flat tip (SF) fiber were compared. Four kilojoules was delivered to a BegoStone over a constant surface area using settings of 0.2/50, 0.6/6, 0.8/8, and 1 J/10 Hz. Fiber tip degradation was measured at 1 and 4 kJ. Ureteroscope deflection was measured with the Olympus URF-P5, URF-P6, and URF-V. Insertion force into a 270° angled ureteroscope sheath model was measured. RESULTS: A sample size of five fibers was used for each comminution energy setting. Comminution increased with pulse energy without significant difference between fibers. No significant differences in tip degradation were observed. Both fibers reduced deflection (10°-30°) in all ureteroscopes without significant differences between fibers. Four new fibers paired with new sheath models were used to test insertion force. The BT insertion forces were approximately one-third of the SF. One SF fiber caused significant damage to the sheath and could not be advanced completely. CONCLUSIONS: The BT fiber has comparable comminution, tip degradation, and ureteroscope deflection performance compared with the SF fiber while exhibiting reduced insertion force within an aggressively deflected working sheath. The new tip design is likely protective of the working channel without loss of performance.

Evaluation of the osteoinductive potential of a bio-inspired scaffold mimicking the osteogenic niche for bone augmentation.

Augmentation of regenerative osteogenesis represents a premier clinical need, as hundreds of thousands of patients are left with insufficient healing of bony defects related to a host of insults ranging from congenital abnormalities to traumatic injury to surgically-induced deficits. A synthetic material that closely mimics the composition and structure of the human osteogenic niche represents great potential to successfully address this high demand. In this study, a magnesium-doped hydroxyapatite/type I collagen scaffold was fabricated through a biologically-inspired mineralization process and designed to mimic human trabecular bone. The composition of the scaffold was fully characterized by XRD, FTIR, ICP and TGA, and compared to human bone. Also, the scaffold microstructure was evaluated by SEM, while its nano-structure and nano-mechanical properties were evaluated by AFM. Human bone marrow-derived mesenchymal stem cells were used to test the in vitro capability of the scaffold to promote osteogenic differentiation. The cell/scaffold constructs were cultured up to 7 days and the adhesion, organization and proliferation of the cells were evaluated. The ability of the scaffold to induce osteogenic differentiation of the cells was assessed over 3 weeks and the correlate gene expression for classic genes of osteogenesis was assessed. Finally, when tested in an ectopic model in rabbit, the scaffold produced a large volume of trabecular bone in only two weeks, that subsequently underwent maturation over time as expected, with increased mature cortical bone formation, supporting its ability to promote bone regeneration in clinically-relevant scenarios. Altogether, these results confirm a high level of structural mimicry by the scaffold to the composition and structure of human osteogenic niche that translated to faster and more efficient osteoinduction in vivo--features that suggest such a biomaterial may have great utility in future clinical applications where bone regeneration is required.

Antiretropulsion devices.

PURPOSE OF REVIEW: Stone migration during the treatment of ureteral stones can prove frustrating and increases both healthcare cost and patient morbidity. Antiretropulsion devices have been engineered to prevent stone migration. RECENT FINDINGS: Improvements in antiretropulsion devices allow for efficient prevention of stone migration during ureteroscopic lithotripsy with minimal adverse effects or complications. Multiple devices are now available each with advantages and disadvantages. New devices are currently engineered to prevent stone migration and maintain ureteral access. Antiretropulsion devices appear to be cost-effective to prevent stone migration during intracorporeal lithotripsy. SUMMARY: Antiretropulsion devices have been safely and effectively used during ureteroscopic procedures. These tools increase stone-free rates, decrease morbidity and new studies have demonstrated their cost-effectiveness.