How to read a postoperative knee replacement radiograph

Knee replacement surgery is the most common joint replacement surgery in England and Wales. Postoperative radiographs are associated with long-term outcome at both early and late stages, and their correct interpretation is therefore vital. These radiographs will commonly be assessed by surgical trainees, emergency doctors, orthopaedic surgeons, nurse practitioners, and radiologists. The aim of this paper is to provide the reader with a systematic approach to assessing these radiographs, whether it be in the immediate postoperative period or during subsequent follow-ups, and to provide sufficient knowledge to critique the procedure. An outline of prostheses and their indications alongside a comprehensive review of the assessment of important angles, alignment, and correct positioning of femoral and tibial components is presented.     

The origin of nausea in migraine–A PET study

Background

Nausea is a common and disabling symptom of migraine. The origin of nausea is not well understood although functional connections between trigeminal neurons and the nucleus tractus solitarius may explain occurrence of nausea with pain. However, nausea occurs as a premonitory symptom in about a quarter of patients, suggesting that a primary brain alteration unrelated to the experience of pain may be the reason for nausea.

Methods

We performed positron emission tomography scans with H₂¹⁵O PET in premonitory phase of nitroglycerin-induced migraine and compared patients with and without nausea.

Results

The results showed activation in rostral dorsal medulla and periaqueductal grey (PAG) in the nausea group, which was absent in the no nausea group. The rostral dorsal medullary area included the nucleus tractus solitarius, dorsal motor nucleus of the vagus nerve and the nucleus ambiguus, all of which are thought to be involved in brain circuits mediating nausea.

Conclusions

The results demonstrate that nausea can occur as a premonitory symptom in migraine, independent of pain and trigeminal activation. This is associated with activation of brain structures known to be involved in nausea. We conclude that nausea is a centrally driven symptom in migraine.     

A Submucosal Antral Mass Caused by Cytomegalovirus Infection in a Patient with Acquired Immunodeficiency Syndrome

A 29-yr-old homosexual man with acquired immunodeficiency syndrome presented with watery diarrhea and fever. Upper gastrointestinal endoscopy was performed to obtain duodenal aspirates and biopsies. A 4-cm submucosal mass in the gastric antrum was identified. Subsequent abdominal CT scan confirmed the presence of this antral mass. An attempt at CT guided needle biopsy was nondiagnostic. Because the mass possibly represented a Kaposi's sarcoma or lymphoma, exploratory laparotomy and open biopsy was performed. Examination of the biopsy specimen showed inflammatory debris with multiple intranuclear cytomegalovirus inclusions. This report describes a case of a submucosal antral mass caused by localized cytomegalovirus infection in a patient with acquired immunodeficiency syndrome.     

ROR1 is essential for proper innervation of auditory hair cells and hearing in humans and mice

Hair cells of the inner ear, the mechanosensory receptors, convert sound waves into neural signals that are passed to the brain via the auditory nerve. Little is known about the molecular mechanisms that govern the development of hair cell–neuronal connections. We ascertained a family with autosomal recessive deafness associated with a common cavity inner ear malformation and auditory neuropathy. Via whole-exome sequencing, we identified a variant (c.2207G>C, p.R736T) in ROR1 (receptor tyrosine kinase-like orphan receptor 1), cosegregating with deafness in the family and absent in ethnicity-matched controls. ROR1 is a tyrosine kinase-like receptor localized at the plasma membrane. At the cellular level, the mutation prevents the protein from reaching the cellular membrane. In the presence of WNT5A, a known ROR1 ligand, the mutated ROR1 fails to activate NF-κB. Ror1 is expressed in the inner ear during development at embryonic and postnatal stages. We demonstrate that Ror1 mutant mice are severely deaf, with preserved otoacoustic emissions. Anatomically, mutant mice display malformed cochleae. Axons of spiral ganglion neurons show fasciculation defects. Type I neurons show impaired synapses with inner hair cells, and type II neurons display aberrant projections through the cochlear sensory epithelium. We conclude that Ror1 is crucial for spiral ganglion neurons to innervate auditory hair cells. Impairment of ROR1 function largely affects development of the inner ear and hearing in humans and mice.Sensorineural hearing loss (SNHL) is diagnosed in approximately 1 per 500 newborns (1). A genetic etiology is present in more than half of the cases. Inner ear anomalies (IEAs), demonstrated with computerized tomography or magnetic resonance imaging, are associated with SNHL in about one-third of individuals (2). Although IEAs can be diagnosed in patients with other clinical manifestations, such as those seen in Waardenburg [Mendelian Inheritance in Man (MIM) 193500], Pendred (MIM 274600), or BOR (MIM 113650) syndromes, the majority of cases fall into the category of nonsyndromic deafness. Despite recent progress in identifying genes that determine many forms of hearing loss (hereditaryhearingloss.org/), the genetic basis of IEAs in humans remains largely unknown.The inner ear is a complex organ that is built from a simple structure, referred to as the otocyst, through a series of morphogenetic events. Roughly, it consists of a dorsal vestibular and a ventral auditory component (3). Studies in model organisms have identified a number of genes that play roles in proper development of the inner ear. Mouse models have been particularly relevant because the anatomy and physiology of the murine auditory system are similar to those of humans. Mutations in human orthologs of many of these genes have been reported to cause deafness in humans as well (4).Next-generation sequencing technologies have allowed rapid identification of novel human deafness genes. Approximately 85% of disease-causing mutations in Mendelian disorders have been found in the protein-coding regions, despite the fact that this portion accounts for less than 2% of the entire human genome (5). Accordingly, whole exome sequencing (WES) has been frequently used because it allows for a targeted enrichment and resequencing of nearly all exons of protein-coding genes.In this study, via WES, we detected a mutation in ROR1 (receptor tyrosine kinase-like orphan receptor 1; MIM 602336), encoding receptor tyrosine kinase-like orphan receptor 1, that associates with an IEA and nonsyndromic deafness in a family. Further characterization of Ror1 mutant mice revealed that Ror1 deficiency results in defective hair cell innervation and abnormal cochlear development.     

Practical applications in stress echocardiography: risk stratification and prognosis in patients with known or suspected ischemic heart disease

OBJECTIVES: The purpose of this study was to define appropriate parameters for risk stratification and prognosis in patients undergoing stress echocardiography. BACKGROUND: Stress echocardiography is an established technique for the diagnosis of coronary artery disease. However, current data on risk stratification of patients undergoing stress echocardiography are limited. METHODS: We evaluated 1,500 patients (59 +/- 13 years old; 51% male) undergoing stress echocardiography (34% with treadmill exercise and 66% with dobutamine). Resting left ventricular ejection fraction (EF) and regional wall motion were assessed by the consensus of two echocardiographers. Follow-up (mean 2.7 +/- 1.0 years) for confirmed non-fatal myocardial infarction (n = 31) and cardiac death (n = 44) were performed. RESULTS: By univariate analysis, both the peak wall motion score index (WMSI) (p < 0.0001) and EF (p < 0.0001) were significant predictors of cardiac events. Peak WMSI effectively risk stratified patients into low (0.9%/year), intermediate (3.1%/year), and high (5.2%/year) risk groups (p < 0.0001). A threshold of 45% EF provided further risk stratification of all WMSI groups. By multivariate logistic regression analysis, peak WMSI (relative risk [RR] 2.1, 95% confidence interval [CI] 1.0 to 4.4; p = 0.04) and EF (RR 1.0, 95% CI 0.9 to 1.0; p = 0.01) were both predictors of cardiac events. CONCLUSIONS: Stress echocardiography yields prognostic information for risk stratification of patients with known or suspected ischemic heart disease. A normal stress echocardiographic study (peak WMSI = 1.0) confers a benign prognosis (0.9%/year cardiac event rate). Peak WMSI >1.7 and EF < or =45% are independent markers of patients at high risk of an adverse clinical outcome.     

Comparison of management patterns and clinical outcomes in patients with atrial fibrillation in Canada and the United States (from the analysis of the Atrial Fibrillation Follow-up Investigation of Rhythm Management [AFFIRM] database)

Little is known about differences in practice patterns or outcomes in the management of patients who have atrial fibrillation in Canada compared with those in the United States (US). We evaluated the effect that the country of enrollment may have on the management patterns and clinical outcomes in patients who participated in the AFFIRM study. Three thousand four hundred patients came from the US and 660 from Canada. In the US, patients were more likely to have a history of coronary artery disease (39% vs 35%, p = 0.03), hypertension (72% vs 67%, p = 0.01), or congestive heart failure (24% vs 18%, p = 0.0002). More US participants were <65 years of age (25% vs 19%, p = 0.003). Although at randomization the use of warfarin was comparable, during follow-up Canadians were more likely to be treated with warfarin and to be therapeutically anticoagulated. Mortality rate at 5 years was higher in US patients (24% vs 16%, p = 0.001), and the composite end point (death, disabling stroke, major bleeding, cardiac arrest, or anoxic encephalopathy) was also higher in US patients (30% vs 22%, p = 0.0005). Even after adjusting for known differences in baseline characteristics, the risk of death was lower in Canada (hazard ratio 0.70, p = 0.02). In conclusion, in the AFFIRM study, US subjects were more likely to have preexisting cardiovascular diseases despite being younger (<65 years old) than those in Canada. Effective warfarin therapy was more commonly employed in Canada. After correcting for the known differences in baseline characteristics, Canadian patients who had atrial fibrillation had a lower mortality risk.     

The implications of lighted ureteral stenting in laparoscopic colectomy.

OBJECTIVE: The placement of indwelling ureteral catheters during colorectal surgery has been recommended for prevention of ureteral injuries. With the advent of laparoscopic colectomy (LCo), the role of preoperative placement of lighted ureteral stents (LUS) has also become commonplace. We sought to evaluate the value of lighted ureteral stent placement in laparoscopic colectomy. METHODS: Sixty-six patients underwent LCo with LUS inserted preoperatively. Stents were removed in the immediate postoperative period. Two surgeons performed all the colectomies; 32 patients were males and 34 were females. Fifty patients underwent sigmoid colectomy, 4 had abdominoperineal resection, 4 had right colectomy, and 1 each had transverse or subtotal colectomy. Eighteen patients had a diagnosis of cancer, 34 had diverticular disease, and 14 had neoplastic polyps. Forty patients had bilateral and 26 had unilateral stent placement. A review of the incidence of ureteral injuries, hematuria, and anuria as the cause of acute renal failure was accomplished, comparing the unilateral and bilateral stented groups. RESULTS: One (1.5%) patient suffered a left ureteral laceration during sigmoid colectomy. This was managed successfully with stent reinsertion. Sixty-five (98.4%) patients had gross hematuria lasting 2.93 days (1 to 6 days). The cost of bilateral stent placement was $1,504.32. A statistically significant difference occurred in the duration of hematuria (days) between patients who had unilateral (2.5 +/- 0.82) and bilateral stent placement (3.37 +/- 1.05), (P < 0.001). Four patients suffered from anuria, 2 required renal support needing hemodialysis for 3 to 6 days, 3 (75%) had bilateral stents, and 1 (25%) had a unilateral stent. CONCLUSIONS: We recommend the placement of lighted ureteral stents as a valuable adjunct to laparoscopic colectomy to safeguard ureteral integrity. Transient hematuria is common but requires no intervention. Reflux anuria occurs infrequently and is reversible.