Porcine Cadaver Research Articles

Universal non-circular cone beam CT orbits for metal artifact reduction imaging during image-guided procedures

Innovation in image-guided procedures has been driven by advances in robotic Cone Beam Computed Tomography (CBCT) systems. A fundamental challenge for CBCT imaging is metal artifacts arising from surgical tools and implanted hardware. Here, we outline how two universal non-circular imaging orbits, optimized for metal artifact reduction, can be implemented in real-time on clinical robotic CBCT systems. Demonstrating potential clinical utility, the universal orbits were implemented during a pedicle screw cervical spine fixation and hip arthroplasty performed on a porcine and ovine cadaver respectively. In both procedures, the universal non-circular orbits noticeably reduced the metal artifacts surrounding the implanted orthopedic hardware, revealing anatomy and soft tissue obscured in current conventional CBCT imaging. This work represents a key step in clinically translating universal orbits, unlocking high quality in-room procedural verification to increase broader use of robotic CBCT systems and reduce the occurrence of secondary corrective surgeries.

A novel training session: mixed reality evisceration surgery webinar.

Evisceration surgery is an important part of an ophthalmologist's skillset but is an uncommon procedure. Therefore, it is important for training ophthalmologists to have adequate knowledge and confidence in this procedure to maximise learning opportunities. Mixed reality involves the intertwining of real and virtual environments and has been used successfully in surgical training. To improve participants' knowledge of the relevant anatomy, steps and confidence in performing evisceration surgery using an extended reality online webinar coupled with conventional teaching. The teaching session comprised of a short lecture introducing evisceration and explaining mixed reality technology including the Microsoft HoloLens headset. This was followed by a 3D demonstration of the orbit and globe, then the live evisceration procedure on a porcine cadaver, with the surgeon's point of view via the headset. There was expert live running commentary during the procedure with the use of virtual signposts on relevant anatomy. Participants were encouraged to be interactive and given the ability to share their annotations on-screen. Ten doctors ranging from Foundation year 1 to Ophthalmology specialist training year 3 attended the 90-min session and completed pre- and post- session questionnaires (5-point Likert scales). Results showed statistically significant improvements in the knowledge, steps and confidence in performing the evisceration surgery (paired two-sample T-tests, SPSS version 29). This study has demonstrated that utilisation of mixed reality with conventional teaching methods can provide a useful initial learning experience which may facilitate effective further learning of the evisceration surgery in a wet-lab or patient setting.

Use of a Porcine Cadaver Model as a Human Surrogate for Behind Armor Blunt Trauma

Abstract Current body armor design evaluation is based on legacy backface deformation criteria for protection, despite limited medical basis. This uniform protection approach, which does not account for anatomical and physiological variability within the torso, may result in heavy armors that limit Warfighter mobility. To optimize armor design, live animal experimentation must be conducted to assess regional injury tolerances; however, the animal and human must first be compared to determine the animal model's viability as a surrogate for thoracoabdominal behind armor blunt trauma (BABT) response. Here, 74 BABT impacts were conducted using ten mid-sized male post-mortem human subjects (PMHS) and ten 40-kg porcine cadavers in matched testing conditions over the lungs, liver, and sternum. Injury risk functions were generated from experimental data and compared across surrogates at each body region. The PMHS and 40-kg porcine cadaver correlated well for chest wall injuries in the lung region, and similarities were noted in high-severity impacts to the liver. Further, assessment of the backface intrusion injury risk function showed regional tolerance differences between anatomical regions, highlighting the need for separate region-specific design criteria. These results indicate that the 40-kg porcine cadaver was an appropriate torso surrogate for certain PMHS regions, such as the ribcage overlaying the lungs and the unprotected liver, in BABT conditions. As this study used cadaveric tissue, future studies should investigate the physiological components of BABT-induced injury in a live animal model, focusing on quantifying regional injury tolerances toward armor design optimization.

Utility of Cadaveric Porcine Heads for Teaching Oral Surgical Procedures in an Australian Dental School: A Pilot Study.

Background/Objectives: Cadaveric models have traditionally been a mainstay of dental and medical education worldwide since their inception. In Australia, educators at dental schools were among the first to use cadaveric porcine heads in formal teaching in oral surgery. This practice has since fallen out of favour in most modern dental curricula. The aim of this pilot study was to determine the utility of cadaveric porcine models for oral surgery training from a student perspective (Griffith University, Gold Coast, Australia). Methods: Thirty participants who were all third-year dental students attended a two-hour session comprising a 30 min lecture followed by a 90 min practical workshop. The lecture outlined the steps and supervision of students during the practical and was provided by a consultant maxillofacial surgeon. At the conclusion of the workshop, participants were asked to anonymously complete a printed questionnaire with eight questions related to their experience. Results: Prior to the workshop, two-thirds (61%) of participants felt that they had been taught the surgical procedure for raising mucoperiosteal flaps adequately in their dental school curriculum during their third year, although only 43% of students had assisted specialty residents in raising a mucoperiosteal flap and 14% reported having performed the procedure themselves. Almost all students (96%) agreed that the porcine model was useful for their dental education and that they would practice the exercise using the model again if provided with the opportunity. The questionnaire had a 93.33% completion rate. Conclusions: This pilot study indicates that porcine heads present a useful, low-cost adjunct in the learning of basic oral surgical procedures.

Evaluation of the MMI Symani® robotic microsurgical system for coronary-bypass anastomoses in a cadaveric porcine model

The MMI Symani® is a recently approved robotic microsurgical system for surgical procedures in adults. The system enables the surgeon to create microanastomoses. Clinical applications so far include lymphatic vessels surgery and the creation of special flap plastics. The use of the system in coronary arteries has not yet been assessed. The aim of this preclinical study was to evaluate the applicability of the Symani® surgical system in the creation of coronary anastomoses a cadaveric porcine model. A total of 12 anastomoses were performed by three senior cardiovascular surgeons on the left main coronary artery of three porcine hearts. Artificial bypasses (diameter 1 mm) were performed to the left main trunk. The anastomoses were performed with the Symani® surgical system. Evaluation included procedure times and anastomosis leakage. All anastomoses could be successfully performed. The procedure time decreased due to the learning curve between the first anastomosis 47:28 ± 5:30 min and the last anastomosis 22:37 ± 3:25 min. The final evaluation of the anastomoses showed excellent results with low leakage. The quality of the anastomosis also improved in relation to the increasing learning curve. The Symani® surgical system could be used to create coronary anastomoses in an acceptable time frame and without technical failures. Hence, the system appears feasible for conventional coronary surgery. Further studies in animal models are mandatory prior to clinical application.

Comparison of Intact Fish Skin Graft and Allograft as Temporary Coverage for Full-Thickness Burns: A Non-Inferiority Study.

The extent and depth of burn injury may mandate temporary use of cadaver skin (allograft) to protect the wound and allow the formation of granulation tissue while split-thickness skin grafts (STSGs) are serially harvested from the same donor areas. However, allografts are not always available and have a high cost, hence the interest in identifying more economical, readily available products that serve the same function. This study evaluated intact fish skin graft (IFSG) as a temporary cover to prepare the wound bed for STSG application. Thirty-six full-thickness (FT) 5 × 5 cm burn wounds were created on the dorsum of six anesthetized Yorkshire pigs on day -1. To mimic the two-stage clinical situation, on day 0, wounds were excised down to a bleeding wound bed and a temporary cover (either IFSG or cadaver porcine skin) was applied; then, on day 7, wounds were debrided to a viable wound bed prior to the application of autologous 1.5:1 meshed STSG (mSTSG). Rechecks were performed on days 14, 21, 28, 45, and 60 with digital images, non-invasive measurements, and punch biopsies. The IFSG created a granulated wound bed receptive to the application of an mSTSG. FT burn wounds treated with an IFSG had similar outcome measures, including contraction rates, trans-epidermal water loss (TEWL) measurements, hydration, and blood perfusion levels, compared to cadaver skin-treated burn wounds. Pathology scoring indicated significant differences between the allograft- and IFSG-treated wounds on day 7, with the IFSG having increased angiogenesis, granulation tissue formation, and immune cells. Pathology scoring indicated no significant differences once mSTSGs were applied to wounds. The IFSG performed as well as cadaver skin as a temporary cover and was not inferior to the standard of care, suggesting the potential to transition IFSGs into clinical use for burns.

Children's toys no longer: a porcine model study of the lethality of modern air rifles.

We observed modern spring-loaded air rifles reaching velocities similar to small-bore rifles, raising concerns about their potential lethality. After encountering two life-threatening thoracic injuries in our practice, we conducted a study to assess the injuries that a commonly available air rifle could cause in a porcine cadaver model. We conducted shooting experiments from 5 and 10 metres away using a .22 calibre spring-loaded airgun, firing five shots into the anterolateral chest on the left side at both distances. Additionally, we repeated the experiment with ten shots into 10% ballistics gel behind an explanted chest wall to evaluate chest wall penetration reliability. Out of the ten combined shots, six resulted in lethal or potentially lethal injuries, including multiple cardiac injuries. Moreover, we observed chest wall penetration in 9 out of 10 shots, with an average penetration depth of 106mm. Non-life-threatening injuries appeared to be influenced by shot location rather than an inability to penetrate the chest wall. Our study raises significant concerns about the potential lethality of unrestricted air rifles in New Zealand. With muzzle velocities comparable to small-bore rifles, these firearms should be reconsidered in terms of regulation and possibly restricted to gun license holders.

A Novel Vascular Anastomotic Coupling Device for End-to-End Anastomosis of Arteries and Veins.

Hand-sutured (HS) techniques remain the gold standard for most microvascular anastomoses in microsurgery. HS techniques can result in endothelial lacerations and back wall suturing, leading to complications such as thrombosis and free tissue loss. A novel force-interference-fit vascular coupling device (FIF-VCD) system can potentially reduce the need for HS and improve end-to-end anastomosis. This study aims to describe the development and testing of a novel FIF-VCD system for 1.5 to 4.0 mm outside diameter arteries and veins. Benchtop anastomoses were performed using porcine cadaver arteries and veins. Decoupling force and anastomotic leakage were tested under simulated worst-case intravital physiological conditions. The 1.5 mm FIF-VCD system was used to perform cadaver rat abdominal aorta anastomoses. Benchtop testing showed that the vessels coupled with the FIF-VCD system could withstand simulated worst-case intravital physiological conditions with a 95% confidence interval for the average decoupling force safety factor of 8.2 ± 1.0 (5.2 ± 1.0 N) and a 95% confidence interval for the average leakage rate safety factor of 26 ± 3.6 (8.4 ± 0.14 and 95 ± 1.4 μL/s at 150 and 360 mmHg, respectively) when compared to HS anastomotic leakage rates (310 ± 14 and 2,100 ± 72 μL/s at 150 and 360 mmHg, respectively). The FIF-VCD system was successful in performing cadaver rat abdominal aorta anastomoses. The FIF-VCD system can potentially replace HS in microsurgery, allowing the safe and effective connection of arteries and veins. Further studies are needed to confirm the clinical viability and effectiveness of the FIF-VCD system.

Tissue Pressure Changes and Implications on Dressing Selection when utilising Negative Pressure Wound Therapy on an Ex Vivo Porcine Model

Negative Pressure Wound Therapy (NPWT) is broadly used in surgical wound management and more recently burn care; however, the tissue pressure changes and best dressing application technique remains unknown. This study was done to help understand the tissue pressure changes beneath negative pressure when varying the delivered pressures, dressing thickness and distribution of dressings.This study was done in 2021 at a quaternary paediatric burns hospital. Utilising a cadaveric porcine model, an intracranial pressure monitor and transducer were used to assess pressure. The transducer was placed on the epidermis or inserted under ultrasound guidance via cannulation to the dermis, subcutaneous or muscular layer. Mepitel™, ACTICOAT™, varying layers of Kerlix™ (10, 20 or 30 layers) and NPWT were then applied either circumferentially or non-circumferentially. Each set of results is indicative of the intracranial pressure probe reading when NPWT was delivered at −40, −60, −80, −100 and −120 mmHg.The median and interquartile pressure recordings were epidermis: −42 (−42.5 – −41), −60.5 (−62.5 – −60), −80.5 (−82 – −80), − 99 (−99 – −98)mmHg (p < 0.001); dermis: 1 (0 − 2), 2 (1 – 3.5), 3 (2 – 5.5), 4 (3 − 7), 5.5 (4 – 7.5)mmHg (p < 0.001) (the increase in pressure was less when circumferential dressings (p < 0.001) or more layers of Kerlix were applied (p < 0.001)); subcutis: 1.5 (−4.5–1), −2.5 (−7.5 – 1.5), −3.5 (−11 – 1.5), −5 (−14 – 1.5) and −6 (−16 – 2)mmHg (p = 006) (the decrease in pressure was less with increased layers of Kerlix (0.047) and muscular: 0 (−0.5 – 0), 0 (−1 – 0.5), 0 (−1 – 1), 0 0 (−1 – 1), 00 (−1.5 – 1)mmHg (p = 0.55).These data suggest negative pressure paradoxically exerts a positive pressure on the dermis. Circumferential and multi-layer dressings reduce this positive pressure. This knowledge has impacted our burn negative pressure wound therapy dressing selection. The limitation of this study is the cadaveric model, a live model is suggested for future studies.

Toward a solid microneedle patch for rapid and enhanced local analgesic action.

Analgesic creams find widespread application as adjuncts for localized anesthesia prior to surgical procedures. Nevertheless, the onset of analgesic action is protracted due to the skin barrier's inherent characteristics, which necessitates prolonged intervals of patient and clinician waiting, consequently impinging upon patient compliance and clinician workflow efficiency. In this work, a biodegradable microneedles (MNs) patch was introduced to enhance the intradermal administration of lidocaine cream to achieve rapid analgesia through a minimally invasive and conveniently accessible modality. The polylactic acid (PLA) MNs were mass-produced using a simple hot-pressing method and served the purpose of creating microchannels across the skin's surface for rapid absorption of lidocaine cream. Optical and electron microscopes were applied to meticulously scrutinize the morphology of the fabricated MNs, and the comprehensive penetration tests involving dynamometer tests, evaluation on porcine cadaver skin, artificial film, optical coherence tomography (OCT), transepidermal water loss, and analysis on rats' skins, demonstrated the robust mechanical strength of PLA MNs for successful intradermal penetration. The behavioral pain sensitivity tests on living rats using Von Frey hair filaments revealed that the MN-assisted lidocaine treatment expeditiously accelerated the onset of action from 40 to 10min and substantially enhanced the efficacy of localized anesthesia. Furthermore, different treatment protocols encompassing the sequence of drug application relative to MN treatment, MN dimensions, and the frequency of MN insertions exhibited noteworthy influence on the resultant local anesthesia efficacy. Together, these results demonstrated that the lidocaine cream followed by diverse PLA MN treatments would be a promising strategy for rapid clinical local anesthesia with wide-ranging applications.

Dexamethasone eluting polydopaminated polycaprolactone-poly (lactic-co-glycolic) acid for treatment of tracheal stenosis.

Tracheal stenosis is commonly caused by injury, resulting in inflammation and fibrosis. Inhibiting inflammation and promoting epithelization can reduce recurrence after initial successful treatment of tracheal stenosis. Steroids play an important role in tracheal stenosis management. This study in vitro evaluated effectiveness of a polydopaminated polycaprolactone stent coated with dexamethasone-eluting poly(lactic-co-glycolic) acid microparticles (μPLGA) for tracheal stenosis management. Polydopamination was characterized by Raman spectroscopy and promoted epithelialization while dexamethasone delivery reduced macrophage activity, assessed by individual cell area measurements and immunofluorescent staining for inducible nitric oxide synthase (iNOS). Dexamethasone release was quantified by high-performance liquid chromatography over 30 days. Activation-related increase in cell area and iNOS production by RAW 264.7 were both reduced significantly (p < .05) through dexamethasone release. Epithelial cell spreading was higher on polydopaminated polycaprolactone (PCL) than PCL-alone (p < .05). Force required for stent migration was measured by pullout tests of PCL-μPLGA stents from cadaveric rabbit and porcine tracheas (0.425 ± 0.068 N and 1.082 ± 0.064 N, respectively) were above forces estimated to occur during forced respiration. Biomechanical support provided by stents to prevent airway collapse was assessed by comparing compressive circumferential stiffness, and stiffness of the stent was about 1/10th of the rabbit trachea (0.156 ± 0.023 N/mm vs. 1.420 ± 0.194 N/mm, respectively). A dexamethasone-loaded PCL-μPLGA stent platform can deliver dexamethasone and exhibits sufficient mechanical properties to anchor within the trachea and polydopamination of PCL is conducive to epithelial layer formation. Therefore, a polydopaminated PCL-μPLGA stent is a promising candidate for in vivo evaluation for treatment of tracheal restenosis.

Moving toward point-of-care surgery in Ukraine: testing an ultra-portable operating room in an active war zone.

In conflict zones, providers may have to decide between delaying time-sensitive surgeries or performing operative interventions in the field, potentially subjecting patients to significant infection risks. We conducted a single-arm crossover study to assess the feasibility of using an ultraportable operating room (U-OR) for surgical procedures on a porcine cadaver abdominal traumatic injury model in an active war zone. We enrolled participants from an ASSET-type course designed to train Ukrainian surgeons before deployment to active conflict zones. They performed three standardized consecutive abdominal surgical procedures (liver, kidney, and small bowel injury repair) with and without the U-OR. Primary outcomes included surgical procedurecompletion rate, procedure time, and airborne particle count at the start of surgery. Secondary survey-based outcomes assessed surgery task load index (SURG-TLX) and perceived operative factors. Fourteen surgeons performed 76 surgical procedures (38 with the U-OR, 38 without the U-OR). The completion rate for each surgical procedure was 100% in both groups. While the procedure time for the liver injury repair did not differ significantly between the two groups, the use of the U-OR was associated with a longer time for kidney (155 vs. 56s, p = 0.002), and small bowel (220 vs. 103s, p = 0.004) injury repair. The average airborne particle count within the U-OR was substantially lower compared to outside the U-OR (6,753,852 vs. 232,282 n/m3, p < 0.001). There was no statistically significant difference in SURG-TLX for procedures performed with and without the U-OR. The use of the U-OR did not affect the procedure completion rate or SURG-TLX. However, there was a marked difference in airborne particle counts between inside and outside the U-OR during surgery. These preliminary findings indicate the potential feasibility of using a U-OR to perform abdominal damage-control surgical procedures in austere settings.

Dose reduction does not impact the precision of CT-based RSA in tibial implants: a diagnostic accuracy study on precision in a porcine cadaver

Background and purpose: Radiostereometric analysis (RSA) is the gold standard for evaluation of migration of implants. CT-RSA has been shown to have precision at the level of RSA in hip, shoulder, and knee joint replacements. We aimed to assess the impact of dose reduction on precision of CT-RSA on tibial implants, comparing it with previously published data on precision of standard dose CT-RSA on tibial implants.Material and methods: We performed a total knee arthroplasty on a porcine knee cadaver, and subsequent CT-RSA with low effective doses (0.02 mSv). We compared the results with previously published CT-RSA data with standard (0.08 mSv) dose. The primary outcome variable was the difference in precision of the maximum total translation (MTT). Secondary variables included ratios of variances and standard deviations, and precision of peripheral point translations, center-of-mass translations, and rotations. A difference of more than 0.1 mm in precision was defined as clinically relevant. Our hypothesis was that precisions of low and standard CT-RSA doses were equal.Results: Low dose (mean 0.07, 95% confidence interval [CI] 0.06–0.08) and standard dose CT-RSA (0.08, CI 0.07–0.09) achieve similar precision, with difference in precision of MTT of 0.01, CI 0.00–0.02 mm. The F-statistic (0.99, CI 0.63–1.55) and sdtest (1.05, CI 0.43–2.58) also supported this.Conclusion: We conclude that the precision of low dose CT-RSA for tibial implants on a porcine cadaver is equal to standard dose CT-RSA. However, these findings should be confirmed in clinical trials.

Phase-Dependent Differential In Vitro and Ex Vivo Susceptibility of Aspergillus flavus and Fusarium keratoplasticum to Azole Antifungals.

Fungal keratitis (FK) is an invasive infection of the cornea primarily associated with Aspergillus and Fusarium species. FK is treated empirically with a limited selection of topical antifungals with varying levels of success. Though clinical infections are typically characterized by a dense network of mature mycelium, traditional models used to test antifungal susceptibility of FK isolates exclusively evaluate susceptibility in fungal cultures derived from asexual spores known as conidia. The purpose of this study was to characterize differences in fungal response when topical antifungal treatment is initiated at progressive phases of fungal development. We compared the efficacy of voriconazole and luliconazole against in vitro cultures of A. flavus and F. keratoplasticum at 0, 24, and 48 h of fungal development. A porcine cadaver corneal model was used to compare antifungal efficacy of voriconazole and luliconazole in ex vivo tissue cultures of A. flavus and F. keratoplasticum at 0, 24, and 48 h of fungal development. Our results demonstrate phase-dependent susceptibility of both A. flavus and F. keratoplasticum to both azoles in vitro as well as ex vivo. We conclude that traditional antifungal susceptibility testing with conidial suspensions does not correlate with fungal susceptibility in cultures of a more advanced developmental phase. A revised method of antifungal susceptibility testing that evaluates hyphal susceptibility may better predict fungal response in the clinical setting where treatment is often delayed until days after the initial insult.

Home Therapies to Neutralize Button Battery Injury in a Porcine Esophageal Model

Button battery ingestion can cause alkaline esophageal injury. There is interest in first-aid household products to neutralize the injury. The objective was to investigate which household products are effective at reducing button battery injury. Two cadaveric porcine experiments were performed. Experiment 1 utilized esophageal mucosal segments. A button battery (3VCR2032) was placed onto the mucosa, and substances (saline control, honey, jam, orange juice, yogurt, milk, and cola) were applied every 10 minutes for 6 applications. Tissue pH was measured every 10 minutes, and macroscopic ulceration size was assessed at 120 minutes. Experiment 2 used an intact esophageal model with a battery inserted into the lumen and jam, honey, and saline irrigation as per experiment 1. Tissue pH, macroscopic and histopathology changes were evaluated at 60, 90 and 120 minutes. In experiment 1, only honey and jam had a lower mean tissue pH at 120 minutes (8.0 [standard deviation [SD] 0.9, n=12] and 7.1 [SD 1.7, n=12], respectively) compared to saline solution 11.9 (SD 0.6, n=6, P<.0001). Both honey (0.24 cm2, SD 0.17) and jam (0.37 cm2, SD 0.40) had smaller mean areas of ulceration compared to saline solution (3.90 cm2, SD 1.03, P<.0001). In experiment 2, honey and jam had significantly lower mean tissue pH at all timepoints compared to saline solution. Histologic changes were evident at 60 minutes in the saline group, whereas honey and jam exhibited no or minimal changes until 120 minutes. Honey and jam were able to neutralize injury caused by a button battery resulting in a smaller area of ulceration. Jam should be further explored as a possible first-aid option as an alternative to honey in suspected button battery ingestion prior to definitive management.

Thawed Porcine Model for Surgical Training: A Novel Conservative Procedure.

Background: General Surgery course is a mandatory in medical schools and continuing surgery training is important even to experienced surgeons which they need to maintain and/or improve their surgical skills. Additionally, the models used for that practice are human cadavers, anesthetized porcine, or simulators and are not accessible for medicine schools or physicians in many countries. Therefore, we present a new technical procedure for preparation of frozen experimental animal's cadavers for medical surgical training. Materials and Methods: To perform the study, one porcine slaughtered and frozen at -20°C was used. The porcine cadaver was thawed at room temperature (25°C) and then the pneumoperitoneum test was performed and viscera inspection carried out. Results: The porcine cadaver took 20 hours to completely thaw. The pneumoperitoneum was successfully performed with total distention of the abdominal cavity. All viscera were well preserved maintaining important in vivo characteristics for consistency. Conclusion: The use of thawed porcine cadaver as a model to train many surgical procedures including videolaparoscopy is feasible. The tissues were well preserved by this method and was financially accessible and could be used for different techniques, equipment, and material tests.

Initiation and accumulation of loading induced changes to native collagen content and microstructural damage in the cartilaginous endplate

BACKGROUND CONTEXTInjury to the cartilaginous endplate (CEP) is linked to clinically relevant low back disorders, including intervertebral disc degeneration and pain reporting. Despite this link to clinical disorders, the CEP injury pathways and the modulating effect of mechanical loading parameters on the pace of damage accumulation remains poorly understood. PURPOSEThis study examined the effect of cyclic loading on the initiation and accumulation of changes to native collagen content (type I, type II) and microstructural damage in the central region of cadaveric porcine CEPs. STUDY DESIGNIn vitro longitudinal study. METHODSOne hundred fourteen porcine cervical spinal units were included (N=6 per group). The study contained a control group (no cyclic loading) and 18 experimental groups that differed by loading duration (1,000, 3,000, 5,000 cycles), joint posture (flexed, neutral), and cyclic peak compression variation (10%, 20%, 40%). Multicolor immunofluorescence staining was used to quantify loading induced changes to type I (ie, subchondral bone) and type II (ie, endplate) native collagen content (fluorescence area, fluorescence intensity) and microstructural damage (pore area [transverse plane], void area along the CEP-bone border [sagittal plane]). RESULTSSignificant main effects of loading duration and posture were observed for fluorescence area and fluorescence intensity of type I and II collagen. In the transverse plane, type II fluorescence area significantly decreased following 1,000 cycles (-12%), but a significant change in fluorescence intensity was not observed until 3,000 cycles (-17%). Type II fluorescence area (-14%) and intensity (-10%) were both significantly less in flexed postures compared to neutral. Similar trends were observed for type I collagen in the sagittal plane sections. Generally, significant changes to fluorescence area were accompanied by the development of microstructural voids along the endplate-subchondral bone border. CONCLUSIONSThese findings demonstrate that microstructural damage beneath the endplate surface occurs before significant changes to the density of native type I and II collagen fibers. Although flexed postures were associated with greater and accelerated changes to native collagen content, the injury initiation mechanism appears similar to neutral. CLINICAL SIGNIFICANCENeutral joint postures can delay the initiation and pace of microdamage accumulation in the CEP during low-to-moderate demand lifting tasks. Furthermore, the management of peak compression exposures appeared relevant only when a neutral posture was maintained. Therefore, clinical low back injury prevention and load management efforts should consider low back posture in parallel with applied joint forces.

Novel mitral/tricuspid annuloplasty sizing device and technique: Proof of concept using a cadaveric porcine heart model.

Novel mitral/tricuspid annuloplasty sizing device and technique: Proof of concept using a cadaveric porcine heart model.

Screws or Sutures? A Pediatric Cadaveric Study of Tibial Spine Fracture Repairs

Background: Tibial spine fractures are common in the pediatric population because of the biomechanical properties of children’s subchondral epiphyseal bone. Most studies in porcine or adult human bone suggest that suture fixation performs better than screw fixation, but these tissues may be poor surrogates for pediatric bone. No previous study has evaluated fixation methods in human pediatric knees. Purpose: To quantify the biomechanical properties of 2-screw and 2-suture repair of tibial spine fracture in human pediatric knees. Study Design: Controlled laboratory study. Methods: Cadaveric specimens were randomly assigned to either 2-screw or 2-suture fixation. A standardized Meyers-Mckeever type 3 tibial spine fracture was induced. Screw-fixation fractures were reduced with two 4.0-mm cannulated screws and washers. Suture-fixation fractures were reduced by passing 2 No. 2 FiberWire sutures through the fracture fragment and the base of the anterior cruciate ligament. Sutures were secured through bony tunnels over a 1-cm tibial cortical bridge. Each specimen was mounted at 30° of flexion. A cyclic loading protocol was applied to each specimen, followed by a load-to-failure test. Outcome measures were ultimate failure load, stiffness, and fixation elongation. Results: Twelve matched pediatric cadaveric knees were tested. Repair groups had identical mean (8.3 years) and median (8.5 years) ages and an identical number of samples of each laterality. Ultimate failure load did not significantly differ between screw (mean ± SD, 143.52 ± 41.9 7 N) and suture (135.35 ± 47.94 N) fixations (P = .760). Screws demonstrated increased stiffness and decreased elongation, although neither result was statistically significant at the .05 level (21.79 vs 13.83 N/mm and 5.02 vs 8.46 mm; P = .076 and P = .069, respectively). Conclusion: Screw fixation and suture fixation of tibial spine fractures in human pediatric tissue were biomechanically comparable. Clinical Relevance: Suture fixations are not biomechanically superior to screw fixations in pediatric bone. Pediatric bone fails at lower loads, and in different modes, compared with adult cadaveric bone and porcine bone. Further investigation into optimal repair is warranted, including techniques that may reduce suture pullout and “cheese-wiring” through softer pediatric bone. This study provides new biomechanical data regarding the properties of different fixation types in pediatric tibial spine fractures to inform clinical management of these injuries.

Laboratory Analysis of Causative Factors for the Final Incision Size due to Intraocular Lens Injector Insertion

In intraocular lens (IOL) implantation, insertion of the IOL injector enlarges the clear corneal incision. A larger incision size (IS) is associated with a higher risk for surgically induced astigmatism and endophthalmitis. The goal of this study was to determine which parameters most influence the final IS. Experimental study. A total of 126 cadaver porcine eyes were included in this study. We analyzed 409 clear corneal incisions made with 126 injectors from 13 injector models. We noted the vertical diameter and the tip angulation for every model. The corneal thickness of each incision location was measured using Scheimpflug tomography. The IS was measured before and after injector insertion and described as preoperative and final ISs, respectively. During surgery, the insertion depth and incision length were documented. A mixed effects model was applied to analyze the influence of the parameters on the final IS. Influence on the final IS. Increases in the vertical diameter of the injector tip, the preoperative IS and the insertion depth, and a reduction of incision length were all significantly associated with increased final IS (P<0.05). The conditional Pseudo-R2-Measure was 0.92. The preoperative IS had the largest standardized estimated effect on the final IS, followed by the vertical diameter of the injector tip, insertion depth, and lastly, incision length. Neither corneal thickness nor the tip angle of the injector had a significant effect on the final IS (P>0.05). The IOL injector's vertical diameter should be as small as possible to ensure a minimal final IS. The injector's insertion depth may be minimized, and the incision length should be long enough to reduce the final IS. Further studies are needed to confirm the findings in human autopsy eyes and in clinical practice. Proprietary or commercial disclosure may be found after the references in the Footnotes and Disclosures at the end of this article..