The utilization of smart trials in PCL retaining knees

Technical issues such as instability, mal-rotation, and mal-alignment continue to be issues leading to total knee replacement revision. Soft tissue balancing is critical to successful address these issues for successful total knee replacement outcomes. Intra-op sensors can now be used to dynamically balance knees in real time and mitigate negative outcomes.     

Early and Long-Term Outcomes in Japanese Patients Aged 80 Years or Older Undergoing Conventional Aortic Valve Replacement

In this study, we investigated the early and long-term results of conventional aortic valve replacement (AVR) in very old patients.Methods: Seventy-five patients with aortic stenosis underwent conventional AVR for patients aged 80 years.We examined early death and major adverse cardiovascular and cerebrovascular event (MACCE).Results: The operative mortality was 0% for isolated AVR and 19.2% for concomitant surgery. The postoperative survival rate and MACCE free-rate were no significant differences between the isolated AVR and the concomitant surgery. Univariate analysis confirmed that cardiac dysfunction, severe chronic kidney disease (CKD), hemodialysis, + coronary artery bypass grafting, and norepinephrine use were risk factor of early death. Univariate analysis confirmed that severe CKD, BNP >1000 pg/ml, aortic cross clamping time (ACCT) >180 min, and non-use carperitide and multivariate analysis confirmed that ACCT >180 min, and non-use carperitide were risk factor of MACCE.Conclusions: This study showed that the results of conventional AVR in very old patients were not satisfactory. However, the results obtained with isolated AVR were favorable with no operative deaths. The present study demonstrated that preoperative cardiac function, preoperative renal function, and operative factors have an important impact on early mortality and MACCE.     

The effect of tranexamic acid on artificial joint materials: a biomechanical study (the bioTRANX study)

Background

Tranexamic acid (TXA) has been successfully used to reduce bleeding in joint replacement. Recently local TXA has been advocated to reduce blood loss in total knee or hip replacement; however, this raised concerns about potential adverse effects of TXA upon the artificial joint replacement.

Materials and methods

In this biomechanical study we compared the effects of TXA and saline upon the following biomechanical properties of artificial joint materials—(1) tensile properties (ultimate strength, stiffness and Young’s modulus), (2) the wear rate using a multi-directional pin-on-plate machine, and (3) the surface topography of pins and plates before and after wear rate testing.

Results

There were no significant differences in tensile strength, wear rates or surface topography of either ultra-high-molecular-weight polyethylene pins or cobalt chromium molybdenum metal plates between specimens soaked in TXA and specimens soaked in saline.

Conclusion

Biomechanical testing shows that there are no biomechanical adverse affects on the properties of common artificial joint materials from using topical TXA.

Level of evidence

V     

Interstitial cystitis/bladder pain syndrome and glycosaminoglycans replacement therapy

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a debilitating chronic disease characterized by discomfort or recurrent abdominal and pelvic pains in the absence of urinary tract infections. Its symptomatology includes discomfort, increased bladder pressure, sensitivity and intense pain in the bladder and pelvic areas, increased voiding frequency and urgency, or a combination of these symptoms. For these reasons, this pathology has a very negative impact on quality of life. The etiology of IC/BPS is still not well understood and different hypotheses have been formulated, including autoimmune processes, allergic reactions, chronic bacterial infections, exposure to toxins or dietary elements, and psychosomatic factors. The finding of an effective and specific therapy for IC/BPS remains a challenge for the scientific community because of the lack of a consensus regarding the causes and the inherent difficulties in the diagnosis. The last recent hypothesis is that IC/BPS could be pathophysiologically related to a disruption of the bladder mucosa surface layer with consequent loss of glycosaminoglycans (GAGs). This class of mucopolysaccharides has hydrorepellent properties and their alteration expose the urothelium to many urinary toxic agents. It has been hypothesized that when these substances penetrate the bladder wall a chain is triggered in the submucosa. In order to improve the integrity and function of the bladder lining, GAG layer replenishment therapy is widely accepted as therapy for patients with IC/BPS who have poor or inadequate response to conventional therapy. Currently, Chondroitin sulfate (CS), heparin, hyaluronic acid (HA), and pentosan polysulphate (PPS), and combinations of two GAGs (CS and HA) are the available substances with different effectiveness rates in patients with IC/BPS. There are four different commercially available products for GAG replenishment including CS, heparin, HA and PPS. Each product has different concentrations and dosage formulations. Recently, a combination of CS and HA is the latest commercially available product with promising results.     

The Permian reptile Opisthodontosaurus carrolli: a model for acrodont tooth replacement and dental ontogeny

Continuous tooth replacement is common for tetrapods, but some groups of acrodont lepidosaurs have lost the ability to replace their dentition (monophyodonty). Acrodonty, where the tooth attaches to the apex of the jawbone, is an unusual form of tooth attachment that has been associated with the highly autapomorphic condition of monophyodonty. Beyond Lepidosauria, very little is known about the relationship between acrodonty and monophyodonty in other amniotes. We test for this association with a detailed study of the dentition of Opisthodontosaurus, an unusual Early Permian captorhinid eureptile with acrodont dentition. We provide clear evidence, both histological and morphological, that there were regular tooth replacement events in the lower jaw of Opisthodontosaurus, similar to its captorhinid relatives. Thus, our study of the oldest known amniote with an acrodont dentition shows that acrodonty does not inhibit tooth replacement, and that many of the characteristics assigned to lepidosaurian acrodonty are actually highly derived features of lepidosaurs that have resulted secondarily from a lack of tooth replacement. In the context of reptilian dental evolution, we propose the retention of the simple definition of acrodonty, which only pertains to the relative position of the tooth at the apex of the jaw, where the jaw possesses equal lingual and labial walls. This definition of implantation therefore focuses solely on the spatial relationship between the tooth and the jawbone, and separates this relationship from tooth development and replacement.     

Measurement techniques to determine tibial rotation after total knee arthroplasty are less accurate than we think

Background

The present study assessed the inter- and intra-observer reliability of tibial and femoral rotation measures after total knee arthroplasty (TKA), and evaluated the correlation between these measurement techniques and their clinical relevance.

Three-dimensional model of surfactant replacement therapy

Surfactant replacement therapy (SRT) involves instillation of a liquid-surfactant mixture directly into the lung airway tree. It is widely successful for treating surfactant deficiency in premature neonates who develop neonatal respiratory distress syndrome (NRDS). However, when applied to adults with acute respiratory distress syndrome (ARDS), early successes were followed by failures. This unexpected and puzzling situation is a vexing issue in the pulmonary community. A pressing question is whether the instilled surfactant mixture actually reaches the adult alveoli/acinus in therapeutic amounts. In this study, to our knowledge, we present the first mathematical model of SRT in a 3D lung structure to provide insight into answering this and other questions. The delivery is computed from fluid mechanical principals for 3D models of the lung airway tree for neonates and adults. A liquid plug propagates through the tree from forced inspiration. In two separate modeling steps, the plug deposits a coating film on the airway wall and then splits unevenly at the bifurcation due to gravity. The model generates 3D images of the resulting acinar distribution and calculates two global indexes, efficiency and homogeneity. Simulating published procedural methods, we show the neonatal lung is a well-mixed compartment, whereas the adult lung is not. The earlier, successful adult SRT studies show comparatively good index values implying adequate delivery. The later, failed studies used different protocols resulting in very low values of both indexes, consistent with inadequate acinar delivery. Reasons for these differences and the evolution of failure from success are outlined and potential remedies discussed.Since the early 1980s, surfactant replacement therapy (SRT) has been successful in applications to prematurely born neonates to treat their lack of surfactant production, which normally initiates late in gestation (1). Because surfactant reduces the surface tension between the air and the lung’s liquid lining, its deficiency creates high surface tensions and collapsed, stiff lungs making them difficult to inflate. The resulting clinical entity of labored breathing and poor oxygenation is called neonatal respiratory distress syndrome (NRDS), or hyaline membrane disease, and is a risk of premature birth increasing with decreasing gestational age. The incidence is ∼1% of all births, equating to 40,000 cases annually in the United States (2). The mortality associated with NRDS dropped from 4,997 deaths in 1980 to 861 in 2005, and SRT played an important role in this success (3).SRT has also been tried in adults whose surfactant systems are compromised by acute respiratory distress syndrome (ARDS). ARDS results from overwhelming infections, mechanical injuries, and other insults either directly or indirectly to the lung. ARDS cases in the United States total 190,600 annually with a 39% mortality rate yielding 74,500 deaths (4). Although some early SRT large-animal and adult clinical trials were successful (5–8), subsequent studies were failures (9–11). The field is looking for direction, with concerns ranging from the delivered surfactant biochemistry to the persistence of the underlying ARDS disease to the adequacy of delivery (12). The model presented here addresses the delivery issue and shows that simulations of these adult SRT studies produce significantly different delivery distributions that can explain success vs. failure.Effective drug delivery is a major medical challenge. First mathematical models for i.v. (13), oral (14), and aerosol (15) modalities contributed to the development of those fields simulating drug uptake, distribution, metabolism, and elimination. The role of models is to interpret data mechanistically, predict outcomes, follow treatment courses, relate dose to response, establish safety criteria, design new drugs and delivery strategies, compare animal experiments to human applications, and tailor protocols to patient specific circumstances. To our knowledge, the work presented here is the first structural model of SRT with the same goals. It quantifies the physics of two-phase fluid flow, air and liquid, into a branching network of airways representing the lung (16–18). Our model provides a mechanistic foundation for SRT delivery, which turns out to be a highly nonlinear process. A working SRT model can have a significant impact on this field, moving it from a process of informed trial and error to one that harnesses the underlying fundamental mechanisms.In SRT, the instilled mixture can form a liquid plug in the trachea (19), which then propagates through the tracheobronchial tree by forced inspiratory airflow. As the liquid plug propagates distally, it coats the airway walls, losing some of its mass, and also splits at bifurcations. Our mathematical model considers these two important steps in sequence. For step A (airway), the propagating plug deposits some content onto the airway walls into a trailing film. This deposition, or coating, reduces efficiency because less surfactant mixture reaches the acinus. Our experimentally validated theory predicts the trailing film thickness as a function of plug viscosity, speed, surface tension, and tube radius from computational fluid dynamics results (17). Then, in step B (bifurcation), the plug splits at an airway bifurcation in an uneven manner due to gravity, favoring the steepest downhill daughter tube, so reduces distribution homogeneity. The larger the structure (adult lungs), the greater is this reduction. For this step, we compute the ratio of the split volumes from conservation of momentum and mass. This split ratio depends on the plug speed, viscosity, surface tension, bifurcation geometry, and orientation with gravity (20, 21). Each step is performed sequentially through a 3D tree construct with the geometrical features of the conducting airways (22, 23) (Materials and Methods). The time period for the flow is a single forced inspiration. A larger fluid velocity yields more even splitting, improving homogeneity, but leaves a thicker wall deposition layer, reducing efficiency. The resulting distribution of SRT depends on the competition between these two fluid mechanical phenomena.     

Management of the painful knee

The painful knee is one of the most common musculoskeletal presentations to primary and secondary care. It is important to distinguish between acute and chronic causes of knee pain, since the urgency of diagnosis and management can be vastly different. This short review covers the common diagnoses that are frequently encountered, with a systematic approach to confirming the diagnosis, and a management strategy.     

Rare case of iatrogenic aortic valve leaflet tear following a diagnostic coronary angiogram

We report a rare case of a 44-year-old male who underwent a diagnostic coronary angiogram following a non-ST elevation myocardial infarction complicated by an aortic valve leaflet tear requiring surgical intervention. Routine transthoracic echocardiogram demonstrated a mobile echogenic structure prolapsing into the left ventricular outflow tract. An intraoperative transesophageal echocardiogram confirmed that the structure originated from the ventricular side of left coronary cusp, causing malcoaptation between left and right coronary cusps, and subsequent moderate to severe aortic regurgitation.