Clinical experiences with a new total wrist prosthesis

Summary For many individuals the preservation of wrist motion is essential for augmentation of fine motor control of the hand and fingers. When significant functional disability exists at the wrist, currently available surgical treatment includes soft tissue arthroplasty, carpectomy, or arthrodesis. A total wrist joint has recently been developed which offers the patient the potential of a pain-free, stable, and mobile wrist. Based upon the principles of total joint replacement as applied to the hip and knee, the prosthesis is secured to the carpus and radius with methylmethacrylate cement following removal of the navicular, lunate, and head of the capitate. The configuration of the prosthesis interface provides for the two planes of motion normally seen at the wrist; 90° of flexion and extension and 50° of radial ulnar deviation are permitted by the design. Candidates for total wrist replacement are patients who exhibit far advanced disease at the wrist and who might be considered for arthrodesis, but in whom the permanent loss of motion would represent a significant handicap. To date, 20 prostheses have been inserted in 17 patients. The longest follow-up is 14 months. All but 2 patients have gained a useful range of motion. All patients have noted dramatic relief of pain and deformity, permitting them to perform tasks which were preoperatively impossible.

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Zusammenfassung Für viele Betroffenen ist die Erhaltung der Handgelenksbeweglichkeit wichtig für die Verstärkung der feinen Muskelkontrolle von Hand und Fingern. Beim Bestehen von erheblichen funktionellen Einschränkungen des Handgelenkes besteht die chirurgische Behandlung gegenwärtig in Fascieninterpositionsplastiken, Carpektomie oder Arthrodese. Eine Handgelenksendoprothese wurde kürzlich entwickelt, die dem Patienten die Möglichkeit eines schmerzfreien, stabilen und beweglichen Handgelenkes bietet. Entsprechend den Prinzipien des totalen Gelenkersatzes für Knie und Hüfte wird diese Prothese am Carpus und Radius mit Methylmethacrylatzement fixiert, nach Entfernung des Os naviculare, Os lunatum und Kopf des Os capitatum. Die Form der artikulierenden Gelenksflächen ermöglicht die Beweglichkeit in zwei Ebenen, die auch normalerweise am Handgelenk besteht. 90° Beugung und Streckung sowie 50° radiale und ulnare Abweichung erlaubt die Konstruktion. Geeignet für Totalersatz des Handgelenkes sind Patienten mit fortgeschrittener Erkrankung des Handgelenkes, die normalerweise für eine Arthrodese vorgesehen sind, jedoch bei denen ein dauerhafter Bewegungsverlust des Handgelenkes eine erhebliche Behinderung bedeutet. Bis heute sind 20 Prothesen in 17 Patienten eingesetzt worden. Der längste Nachuntersuchungszeitraum beträgt 14 Monate. Bis auf 2 Patienten haben alle einen brauchbaren Bewegungsumfang erreicht. Alle Patienten haben eine deutliche Erleichterung der Schmerzen und Deformität festgestellt, die ihnen ermöglicht, Arbeiten auszuführen, die präoperativ nicht möglich waren.

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The prosthesis is being manufactured by How-medica, International.     

Bilateral total knee replacement under one anesthetic.

The postoperative results and complications among 41 patients undergoing bilateral total knee arthroplasty were compared with 40 patients who underwent unilateral total knee replacement. Among the bilateral group, the most common diagnosis was rheumatoid arthritis (68%), while degenerative arthritis prevailed in the unilateral group (50%). Preoperatively, patients in the bilateral group exhibited generally a greater degree of physical disability and limitation of activity due to multiple joint involvement. Postoperatively, no change in the arc of motion was noted in either group, although flexion contractures were significantly diminished in both. The degree of postoperative pain relief was identical in both groups as was the decreased need for walking devices. The most commonly observed complication among the unilateral group was prosthetic loosening (12.%). This was felt explainable on the basis of the increased postoperative activity level of patients with degenerative arthritis and single joint disease. Patients in the bilateral group showed a higher incidence of wound problems, presumably secondary to the long-term use of steroids. The infection rate was identical in each group, but the bilateral group displayed a higher incidence of pulmonary emboli (9.7 vs. 2.5%). The postoperative need for rehabilitation services and the duration of time before dependent walking was achieved was not prolonged in the bilateral group. Hospitalization of the bilateral group was increased only 20%. No deaths were reported in either group. When the need for total knee replacement exists bilaterally, bilateral replacement with a single anesthetic would appear reasonable, provided careful patient selection and technical guidelines are followed.     

Intravenous angiography using scanned projection radiography: preliminary investigation of a new method

The use of digital subtraction techniques combined with fluoroscopy has rekindled interest in arteriography using intranvenous injections of contrast media. A new method is proposed for intravenous angiography in which an x-ray source and xenon detector array from a computed tomographic (CT) scanner are used to scan a region of interest to produce projection image. In order to provide adequate visualization of small concentrations of iodine in blood vessels, a subtraction scheme is used to remove the contribution from overlapping soft tissue and bone. Initial experiments with a temporal subtraction algorithm on phantoms have demonstrated the ability to image simulated blood vessels of 1.7-mm diameter containing dilute diatrizoate with an iodine concentration of 3.7 mg/cc, at an exposure of less than 100 mR. Vascular structures 5-8 mm in diameter have been imaged in dogs with iodine concentrations of less than 37 mg/cc using temporal subtraction. Principal advantages of the method over other film or fluoroscopic subtraction techniques are: 1) wide dynamic range an low noise of the (CT) detectors, providing excellent iodine sensitivity; 2) high scatter rejection; and 3) efficient utilization of x-ray dose.     

Quantitative T*2‐mapping based on multi‐slice multiple gradient echo flash imaging: Retrospective correction for subject motion effects

Numerous clinical and research applications for quantitative mapping of the effective transverse relaxation time T*₂ have been described. Subject motion can severely deteriorate the quality and accuracy of results. A correction method for T*₂ maps acquired with multi‐slice multiple gradient echo FLASH imaging is presented, based on acquisition repetition with reduced spatial resolution (and consequently reduced acquisition time) and weighted averaging of both data sets, choosing weighting factors individually for each k‐space line to reduce the influence of motion. In detail, the procedure is based on the fact that motion artifacts reduce the correlation between acquired and exponentially fitted data. A target data set is constructed in image space, choosing the data yielding best correlation from the two acquired data sets. The k‐space representation of the target is subsequently approximated as linear combination of original raw data, yielding the required weighting factors. As this method only requires a single acquisition repetition with reduced spatial resolution, it can be employed on any clinical system offering a suitable sequence with export of modulus and phase images. Experimental results show that the method works well for sparse motion, but fails for strong motion affecting the same k‐space lines in both acquisitions. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

Methamphetamine administration reduces hippocampal vesicular monoamine transporter-2 uptake

Repeated high-dose injections of methamphetamine (METH) rapidly decrease dopamine uptake by the vesicular monoamine transporter-2 (VMAT-2) associated with dopaminergic nerve terminals, as assessed in nonmembrane-associated vesicles purified from striata of treated rats. The purpose of this study was to determine whether METH similarly affects vesicular uptake in the hippocampus; a region innervated by both serotonergic and noradrenergic neurons and profoundly affected by METH treatment. Results revealed that repeated high-dose METH administrations rapidly (within 1 h) reduced hippocampal vesicular dopamine uptake, as assessed in vesicles purified from treated rats. This reduction was likely associated with serotonergic nerve terminals because METH did not further reduce vesicular monoamine uptake in para-chloroamphetamine-lesioned animals. Pretreatment with the serotonin transporter inhibitor fluoxetine blocked both this acute effect on VMAT-2 and the decrease in serotonin content observed 7 days after METH treatment. In contrast, there was no conclusive evidence that METH affected vesicular dopamine uptake in noradrenergic neurons or caused persistent noradrenergic deficits. These findings suggest a link between METH-induced alterations in serotonergic hippocampal vesicular uptake and the persistent hippocampal serotonergic deficits induced by the stimulant.     

Identifying patients with cellulitis who are likely to require inpatient admission after a stay in an ED observation unit

Background

Emergency department observation units (EDOU) are often used for patients with cellulitis to provide intravenous antibiotics followed by a transition to an oral regimen for discharge. Because institutional regulations typically limit EDOU stays to 24 hours, patients lacking a clinical response within this period will often be subsequently admitted to the hospital for further treatment.

Objective

The aim of this study was to determine the rate of hospital admission and characteristics predictive of admission in patients with cellulitis who are initially placed in an ED observation unit.

Methods

A retrospective cohort study of patients placed into EDOU with a diagnosis of skin infection was conducted. Age, sex, history of diabetes mellitus, immunosuppression, intravenous drug use, location of cellulitis, presence of abscess, laboratory infectious markers, vital signs, and outpatient antibiotic treatment were recorded. The primary outcome was a hospital admission due to failure to respond to treatment within the 24-hour observation time window. Significant variables on univariate analysis were used to create a multivariate analysis, which identified predictive characteristics.

Results

Four hundred six patient charts were reviewed, with 377 meeting inclusion criteria; the inpatient admission rate from EDOU was 29.2%. Using logistic regression techniques, we created a model of independent predictors for need of admission after 24 hours: cellulitis of the hand (odds ratio [OR], 2.9; 95% confidence interval [CI], 1.8-4.9), measured temperature higher than 100.4°F (OR, 2.5; 95% CI, 1.1-5.5), and lactate greater than 2 (OR, 3.1; 95% CI, 1.3-7.3) were predictive of failure of ED observation.

Conclusions

Patients with cellulitis placed into ED observation status were more likely to fail an observation trial if they had an objective fever in the ED, an elevated lactate, or a cellulitis that involved the hand.     

Patient and observer ratings of physician shared decision making behaviors in breast cancer consultations

Objective

Explore the validity of using patient reports to measure shared decision making (SDM).

Methods

178 patients diagnosed with breast cancer obtained SDM assistance in a university-based clinic. Trained observers rated physician SDM behaviors and surveyed patients. We calculated the frequency with which patients and observers reported maximum SDM behaviors for each survey item. We also calculated agreement frequency between patients and observers.

Results

Over 90% of patients rated doctors as reflecting SDM competencies. Patients reported doctors making recommendations more than soliciting their preferred choice (90% vs. 69%, p < 0.001). Patients heard benefits discussed “a lot” more often than they heard risks and side effects discussed “a lot” (81% vs. 58%, p < 0.001). Agreement between patients and observers was 75%. In cases of disagreement, patients more frequently perceived SDM behaviors than did observers (15% vs. 9%, p = 0.002), suggesting a possible agreement bias.

Conclusions

High agreement supports further investigation into using patients as efficient and effective raters of SDM. Patient ratings may be inflated by agreement bias.

Practice implications

Doctors presentations may be biased toward discussing benefits more than risks. Policy makers can solicit patient ratings of SDM as long as they are aware of possibly inflated ratings due to agreement bias.     

Preparation and analysis of styrene oligomers containing migrates from various polystyrenes used in food packaging

An oligostyrene-like product (F2L5250) was reported to have estrogen-like activity (statistically significant increases in means for absolute uterine weight and the ratios of the uterine weight to terminal body weight) in juvenile female rats provided a dietary concentration of 100 ppm F2L5250 for four consecutive days. The highest no-effect-level (NOEL) for estrogenic activity was 80 ppm in the diet, corresponding to a daily intake of 13.3 mg F2L5250/kg. Although it is unlikely that such estrogenic tetramers would occur in commercial polystyrene, the Styrene Steering Committee (SSC) of the European Chemical Industry Council (CEFIC) sponsored the current extensive project to address any concern that human consumption of styrene oligomers migrating from polystyrene containers into food, e.g., from packaged yoghurt, or from the use of EPS coffee cups and related products, might affect human health. To ensure confidentiality and compliance with the highest scientific and regulatory standards, the entire project was conducted without knowledge of the oligomer migrates tested, and all activities were managed and audited under a contract between the SSC and a third party, Argus International. This paper describes the preparation and analyses of the 23 representative polystyrenes [9 general purpose polystyrenes (GPPS), 8 high impact polystyrenes (HIPS) and 6 expandable polystyrenes (EPS)] evaluated for estrogenicity in an in vivo uterotrophic assay in immature female rats. The polystyrene samples were chosen to represent food packaging applications. They were obtained from participating European Polystyrene Manufacturers, coded at the TNO Nutrition and Food Research Institute, Utrecht, The Netherlands (TNO) and sent to BASF, Ludwigshafen, Germany for preparation of test bars (GPPS and HIPS) or test foam parts (EPS). The prepared polystyrene test bars or test foam parts were submitted to elution with 50% aqueous (v/v) ethanol for 10 days at 40 degrees C, a procedure which simulates an exposure at ambient temperature for several weeks and represents an exaggeration in comparison with yogurt, for which directive 85/572/EEC1 defines 3% aqueous acetic acid as the official food simulant. To further exaggerate the potential concentration of the possible migrates, the surface/volume ratio selected for elution was the maximum experimentally possible, i.e., approximately 56 dm2/kg food for the GPPS and HIPS bars and approximately 38 dm2/kg food for the EPS foam, representing a multiple of approximately 9 (GPPS and HIPS) and 6 (EPS), times the conventional surface/volume ratio of 6 dm2/kg. These obtained styrene oligomer migrates were then diluted to 25% aqueous (v/v) ethanol, a concentration that could be tolerated by the test animals. After dilution, the low and high concentrations represented multiples of 0.5 and 4.6 (GPPS and HIPS) and 0.5 and 3.2 (EPS) the conventional surface/volume ratio, respectively. These levels simulated daily human consumption of 500 or 5,000 g of food for the GPPS and HIPS samples and of 500 or 3,150 g of food for the EPS samples, respectively. The results of the homogeneity, stability and concentration analyses of the styrene dimers and trimers in the migrates indicated that the concentrations of migrants were highest as the result of 50% aqueous ethanol extraction of HIPS test bars followed by GPPS test bars and EPS test foam parts.