National Joint Registry recorded untoward intraoperative events during primary total hip arthroplasty: an investigation into the data accuracy, causal mechanisms and attributability

INTRODUCTION

Untoward intraoperative events occurring during total hip arthroplasty are recorded by the National Joint Registry through Minimum Data Set (MDS) forms. This data may be used to assess the safety of implants. The aim of this study is to evaluate the accuracy of the untoward intraoperative events, assess the mechanism and ascertain whether these events were attributable to the implants inserted.

METHODS

A retrospective analysis was undertaken of primary total hip arthroplasties performed between 2005 and 2018 in which an untoward intraoperative event was recorded.

RESULTS

Of 12,802 primary hip replacements, 64 patients (0.5%) had untoward intraoperative events recorded on the MDS form. In 43 of 64 cases, the intraoperative untoward event recorded on the MDS form matched the operation notes. Among these 43 cases, in 30 (69%) patients the intraoperative event could be attributed to the implant recorded. In the remaining 13 (31%) cases, the events recorded could not be attributed to the implant. In six cases, the untoward events were attributed to implants used to manage the events rather than the implants which caused them. In seven cases, the untoward events were related to surgical technique rather than to the implant or instrumentation.

CONCLUSIONS

Our analysis highlights that all untoward intraoperative events recorded on the NJR form are not implant related or attributable to the implant inserted. Provision should be made on the MDS form to clarify whether a particular untoward intraoperative event was related to the implant inserted.

Maternal-placental-fetal biodistribution of multimodal polymeric nanoparticles in a pregnant rat model in mid and late gestation

Multimodal polymeric nanoparticles have many exciting diagnostic and therapeutic applications, yet their uptake and passage by the placenta, and applications in the treatment of pregnancy complications have not been thoroughly investigated. In this work, the maternal-fetal-placental biodistribution of anionic and cationic multimodal poly(glycidyl methacrylate) (PGMA) nanoparticles in pregnant rats at mid (ED10) and late (ED20) gestation was examined. Fluorescently-labelled and superparamagnetic PGMA nanoparticles functionalized with/without poly(ethyleneimine) (PEI) were administered to pregnant rats at a clinically-relevant dose and biodistribution and tissue uptake assessed. Quantitative measurement of fluorescence intensity or magnetic resonance relaxometry in tissue homogenates lacked the sensitivity to quantify tissue uptake. Confocal microscopy, however, identified uptake by maternal organs and the decidua (ectoplacental cone) and trophoblast giant cells of conceptuses at ED10. At ED20, preferential accumulation of cationic vs. anionic nanoparticles was observed in the placenta, with PGMA-PEI nanoparticles localised mainly within the chorionic plate. These findings highlight the significant impact of surface charge and gestational age in the biodistribution of nanoparticles in pregnancy, and demonstrate the importance of using highly sensitive measurement techniques to evaluate nanomaterial biodistribution and maternal-fetal exposure.

Therapeutic and safety considerations of nanoparticle-mediated drug delivery in pregnancy

Advances in nanotechnology have resulted in the design of effective, safe and tissue-selective nanocarriers for delivering therapeutics to treat malignancies, infections and other diseases. In pregnancy, nanoparticle-based drug formulations could have the potential to selectively target either the placenta and/or fetus, enabling ‘fetal-friendly’ drugs to be administered in pregnancy with minimal risk of off-target effects. A considerable amount of research has been carried out on maternal-placental-fetal nanoparticle uptake, transfer and toxicity using rodent and ex vivo models. However, the development of placental targeting strategies and the therapeutic evaluation of nanoformulations in pregnancy remains in its infancy. While some promising avenues are currently under investigation, much work is needed to bring the advantages of nanoparticle-based drug therapy in pregnancy to clinical reality.

Impairments to the GH-IGF-I axis in hSOD1G93A mice give insight into possible mechanisms of GH dysregulation in patients with amyotrophic lateral sclerosis

GH deficiency has been found in subjects with amyotrophic lateral sclerosis (ALS). Disrupted endocrine function could contribute to the progressive muscle loss and hypermetabolism seen in ALS. It is not possible to study all the elements of the GH-IGF-I axis in ALS patients. Consequently, it remains unclear whether dysfunctional GH secretion contributes to disease pathogenesis and why GH and IGF-I directed treatment strategies are ineffective in human ALS. The hSOD1(G93A) transgenic mouse model is useful for the detailed investigation of the pathogenesis of ALS. We report that symptomatic male hSOD1(G93A) transgenic mice exhibit a deficiency in GH secretion similar to that seen in human ALS. Further characterization of the GH-IGF-I axis in hSOD1(G93A) mice reveals central and peripheral abnormalities that are not found in wild-type age-matched controls. Specifically, we observe aberrant endogenous pulsatile GH secretion, reduced pituitary GH content, and decreased circulating levels of IGF-I, indicating global GH deficiency in hSOD1(G93A) mice. Furthermore, a reduction in the expression of the IGF-I receptor α-subunit in skeletal muscle and lumbar spinal cords of hSOD1(G93A) mice suggests impaired IGF-I signaling within these tissues. This is the first account of disrupted GH secretion in a transgenic mouse model of ALS. These observations are essential for the development of effective GH and IGF-I targeted therapies in ALS.

GH does not modulate the early fasting-induced release of free fatty acids in mice

Fasting results in the mobilization of adipose stores and the elevation of levels of free fatty acids (FFA). In humans, this process is driven by a release in GH. Little is known regarding the role of GH in modulating this process during early stages of fasting in the mouse. Confirmation of the role of GH in modulating FFA release in the fasting mouse is of particular importance given the frequent use of mouse models to study metabolic mechanisms. Here, we correlate the initial release of FFA throughout fasting in mice with pulsatile GH secretion. Observations illustrate the rapid release of FFA in response to food withdrawal. This does not correlate with a rise in GH secretion. Rather, we observed a striking loss in pulsatile secretion of GH throughout the first 6 h of fasting, suggesting that GH does not modulate the initial release of FFA in the mouse in response to fasting. This was confirmed in GH receptor knockout mice, in which we observed a robust fasting-induced rise in FFA. We further illustrate the dynamic relationship between the orexigenic and anorexigenic hormones ghrelin and leptin during fasting in the mouse. Our findings show an initial suppression of leptin and the eventual rise in circulating levels of acyl-ghrelin with fasting. However, altered acyl-ghrelin and leptin secretion occurs well after the rise in FFA and the suppression of GH secretion. Consequently, we conclude that although acyl-ghrelin and leptin may modulate the physiological response to drive food intake, these changes do not contribute to the initial loss of pulsatile GH secretion. Rather, it appears that the suppression of GH secretion in fasting may occur in response to an elevation in fasting levels of FFA or physiological stress. Observations highlight a divergent role for GH in modulating FFA release between man and mouse.

Development of a method for the determination of pulsatile growth hormone secretion in mice

Measures of pulsatile GH secretion require frequent collection and analysis of blood samples at regular intervals. Due to blood volume constraints, repeat measures of circulating levels of GH in mice remain challenging. Consequently, few observations exist in which the pulsatile pattern of GH secretion in mice have been characterized. To address this, we developed a technique for the collection and analysis of circulating levels of GH at regular and frequent intervals in freely moving mice. This was achieved through the development of a sensitive assay for the detection of GH in small (2 μl) quantities of whole blood. The specificity and accuracy of this assay was validated following guidelines established for single-laboratory validation as specified by the International Union of Pure and Applied Chemistry. We incorporated an established method for tail-clip blood sample collection to determine circulating levels of GH secretion in 36 whole blood samples collected consecutively over a period of 6 h. Resulting measures were characterized by peak secretion periods and interpulse stable baseline secretion periods. Periods characterized by elevated whole blood GH levels consisted of multicomponent peaks. Deconvolution analysis of resulting measures confirmed key parameters associated with pulsatile GH secretion. We show a striking decrease in pulsatile GH secretion in mice after 12-18 h of fasting. This model is necessary to characterize the pulsatile profile of GH secretion in mice and will significantly contribute to current attempts to clarify mechanisms that contribute to the regulation of GH secretion.

Early hepatocellular carcinoma presenting with biliary ductal invasion--a case report

Early and small hepatocellular carcinoma (HCC) rarely presents with biliary ductal invasion. We present a case of early HCC presenting with biliary invasion, in the absence of a mass on computed tomographic scanning. The patient, a hepatitis B carrier, was initially diagnosed to have "liver fluke infection" after a "leaf-like structure" was found within the right hepatic duct on endoscopic retrograde cholangiopancreatography (ERCP). The specimen was retrieved with a Dormia basket. Histology revealed HCC. This report highlights an unusual case of early and small HCC presenting with biliary ductal invasion. A high index of suspicion has to be entertained in the background of hepatitis B regardless of the atypicality of presentation.

The elimination half-life of urinary cotinine in children of tobacco-smoking mothers

Exposure to environmental tobacco smoke (ETS) is strongly associated with childhood morbidity. Cotinine, the major metabolite of nicotine, is a useful marker of tobacco smoke exposure. Cotinine levels in infants are higher than in older children or adults exposed to the same reported quantity of ETS. One hypothesis to explain this difference is that the urinary elimination half-life of cotinine is different between infants and older children. Urine was collected at admission, 12, 24 and 48 h, cotinine levels were subsequently measured and then standardized by correcting for creatinine excretion. Urinary elimination half-life of cotinine was calculated in 31 infants and 23 older children. The median half-life was 28.3 h (range 6.3-258.5 h) in infants, and 27.14 h (range 9.7-99.42 h) in older children. A Mann-Whitney U test showed no significant difference in the median half-life of cotinine between the two age groups (P = 0.18). Multivariate linear regression analysis demonstrated no significant relationship between half-life of cotinine and corrected cotinine level (P = 0.24). Our results support the hypothesis that higher cotinine levels in infants is due to greater exposure, rather than slower metabolism of cotinine.