Ligament balancing in computer-assisted total knee arthroplasty: improved clinical results with a spring-loaded tensioning device.

Total knee arthroplasty (TKA) remains one of the most successful procedures in orthopaedic surgery. Complications certainly exist and are often related to failure of knee ligament balance. This asymmetry subsequently leads to component mal-alignment and loosening often secondary to deviation of the lower extremity mechanical axis. Understanding knee mechanics is essential, and recent technological advances have begun to minimize postoperative problems. A tensioning device that respects the native patellofemoral anatomy as well as the natural ligamentous strains has been developed. The surgical integration of computer-assisted navigation has allowed for enhanced accuracy and subsequently better results. The purpose of the current paper is to discuss the evolution of an improved ligament tensioning device, in the setting of classic mechanical guidance versus computer assistance and its postoperative impact on total knee outcomes in terms of manipulation rates and two-year radiographic alignment data. Based on a single surgeon series, mechanically guided arthroplasties resulted in a 16 per cent manipulation rate. Computer assistance with spacer blocks decreased the manipulation rate to 14 per cent, while using a novel tensioner device further decreased the manipulation rate to 7 per cent, a significant difference of p < 0.01. Radiographic data illustrate all TKAs with the tensioner to be within 4 degrees of the desired position.

Ion concentrations from hip implants.

Total hip joint arthroplasty is performed in increasing numbers--about 0.16-0.2% of population per year in industrial countries. In most cases, an implant is a metallic component articulating with a metal, ceramic, or polyethylene liner, used in the hip, knee, and spine. The metal implants release ions in vivo. Toxic concentrations of ions can lead to many adverse physiological effects, including cytotoxicity, genotoxicity, carcinogenicity, and metal sensitivity. Reference levels of ion concentrations in body fluids and tissues determined by many studies are compiled, reviewed, and presented in this article. The concentrations of ions released from different alloys--including cobalt, chromium, nickel, molybdenum titanium, aluminum, and vanadium--are also presented. This article reviews the literature pertaining to clinical data on metal ion concentrations in patients with metal joint prostheses and laboratory data on the physiological effects of the metals.

Increased histone acetyltransferase and lysine acetyltransferase activity and biphasic activation of the ERK/RSK cascade in insular cortex during novel taste learning.

Changes in gene expression are thought to be involved in neuronal plasticity associated with learning and memory. Although acetylation of lysine residues on histones by histone acetyltransferases (HAT) is an obligatory component of transcription, HAT activity has been largely ignored in studies of the nervous system. We developed a new model for studying novel taste learning using novel solid food presentation to nondeprived animals. Using this behavioral paradigm, we investigated short- and long-term regulation of lysine acetyltransferase activity and the ERK/mitogen-activated protein kinase (MAPK)/RSK cascade in insular cortex, a CNS region known to be crucial for the formation of novel taste memories. We observed that novel taste learning elicited biphasic (acute and long-lasting) activation of two distinct lysine acetyltransferase activities along with the ERK/MAPK cascade in insular cortex. In vitro studies revealed that the ERK cascade could regulate the lysine acetylation of a 42 kDa lysine acetyltransferase substrate, suggesting a causal relationship between ERK activation and lysine acetyltransferase activity in insular cortex. Overall, our studies reveal an unanticipated long-lasting activation of insular cortex signal transduction cascades in novel taste learning. Furthermore, our studies suggest the hypothesis that acute and long-term ERK activation and lysine-histone acetyltransferase activation may play a role in regulating gene expression in single-trial learning and long-term memory formation.

Activation of ERK/MAP kinase in the amygdala is required for memory consolidation of pavlovian fear conditioning.

Although much has been learned about the neurobiological mechanisms underlying Pavlovian fear conditioning at the systems and cellular levels, relatively little is known about the molecular mechanisms underlying fear memory consolidation. The present experiments evaluated the role of the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) signaling cascade in the amygdala during Pavlovian fear conditioning. We first show that ERK/MAPK is transiently activated-phosphorylated in the amygdala, specifically the lateral nucleus (LA), at 60 min, but not 15, 30, or 180 min, after conditioning, and that this activation is attributable to paired presentations of tone and shock rather than to nonassociative auditory stimulation, foot shock sensitization, or unpaired tone-shock presentations. We next show that infusions of U0126, an inhibitor of ERK/MAPK activation, aimed at the LA, dose-dependently impair long-term memory of Pavlovian fear conditioning but leaves short-term memory intact. Finally, we show that bath application of U0126 impairs long-term potentiation in the LA in vitro. Collectively, these results demonstrate that ERK/MAPK activation is necessary for both memory consolidation of Pavlovian fear conditioning and synaptic plasticity in the amygdala.

Orthopedic personnel roles in the OR for computer assisted total knee arthroplasty.

The methods and problems associated with traditional total knee arthroplasty surgery and the development and advantages of computer-assisted surgery (CAS) are discussed in this article. In the next decade, CAS products have the potential to transform as many as 25% of all orthopedic surgical procedures from techniques that largely depend on line of sight and traditional instruments to techniques that use integrated surgical instruments and computer technology. This technology could revolutionize orthopedic surgery, the lives of patients, and the work of perioperative staff members during the next decade.

Two-dimensional echocardiograms of a transvenous left ventricular pacing catheter.

A permanent transvenous pacemaker lead was placed across the atrial septum and retained in the left ventricle for eight years. M-mode echocardiograms showed a linear echocardiographic density in the left atrium and mitral valve. Cross-sectional echocardiograms further defined the location and course of the pacing lead.

Effect of intra-aortic balloon pumping on nutrient coronary flow in normal and ischemic myocardium.

The effects of intra-aortic balloon pumping (IABP) on myocardial flow distribution were studied in 50 dogs. Cardiac output was controlled by right heart bypass. In each dog the following parameters were measured with and without IABP during normal coronary perfusion and after regional ischemia was induced by anterior descending coronary vein flow by timed collection, and endocardial/epicardial flow ratios by a previously reported thermal washout technique. In nonischemic myocardium, IABP significantly (p less than 0.05) increased mean coronary sinus flow 11.5 percent +/- 5.8 percent (S.D.) and the mean endocardial/epicardial ratio, 17.3 percent +/- 0.28 percent. In the regionally ischemic myocardium, IABP significantly (p less than 0.05) increased mean segmental coronary vein flow 13.9 percent +/- 1.23 percent but decreased the endocardial/epicardial ratio 29.9 percent +/- 1.1 percent. We conclude that in the dog, IABP enhances subendocardial blood flow in perfused but not in ischemic myocardium. Contrary to common suppositions, the increase in collateral blood flow with IABP preferentially supplies epicardial layers in segmental ischemic zones, but may be shunted from the subendocardium.

Phosphorylation of MAP kinase and CREB in mouse cortex and amygdala during taste aversion learning.

Mice were subjected to a taste aversion conditioning procedure in which they drank water, familiar saccharin, or novel saccharin, followed by injection of either NaCl or the emetic agent LiCl. Immunohistochemistry was used to localize phosphorylated MAP kinase (ppERK) and phosphoCREB (pCREB) in the brain shortly after conditioning. An examination of insular cortex and amygdala revealed specific phosphorylation of MAP kinase by novel saccharin and LiCl, and CREB by LiCl. Pairing of novel saccharin with LiCl was the only stimulus sufficient to increase ppERK and pCREB immunoreactivity in the lateral amygdala, suggesting this as a site of CS-US convergence. ppERK immunoreactivity was localized to both nuclear and non-nuclear compartments, suggesting multiple functional roles of MAP kinase during learning.

Coordinate regulation of Fos and Jun proteins in mouse brain by LiCl.

Expression of the bZIP transcription factor c-Fos in the nucleus tractus solitarius (NTS) of the brain stem may allow for genomic encoding of an unconditioned stimulus (US) during taste aversion learning. Dimerization of c-Fos with other bZIP proteins of the Jun family is necessary to enable transcriptional efficacy at the AP-1 sequence of putative target gene promoter regions. The present study examined the regulation of Fos and Jun proteins by LiCl. Double immunofluorescence labelling revealed that LiCl causes a coordinate upregulation of c-Fos, FosB and JunB, and these proteins are colocalized in a majority of cells examined in NTS, parabrachial nucleus (PBN), and central nucleus of the amygdala (CeA). This study demonstrates that a coordinate signalling response occurs in relevant brain regions in response to LiCl.

c-Fos antisense blocks acquisition and extinction of conditioned taste aversion in mice.

Conditioned taste aversion is an unusual form of associative learning in which long delays between conditional stimulus taste (CS) and unconditioned stimulus illness (US) suggest stimulus encoding by novel mechanisms. Recent data suggest that stimulus inputs are encoded by inducible bZIP proteins, the kinetics of which match the temporal features of the CS and US in taste aversion learning. Blockade of US-induced c-Fos translation in the brain stem by antisense oligonucleotides specifically blocks both acquisition and extinction of a learned taste aversion, but does not impair sensory processing of either CS or US, suggesting that c-Fos antisense blocks associative events within NTS necessary to support taste aversion learning.

Acute blunt traumatic rupture of the diaphragm in children.

Two patients had acute rupture of the diaphragm from blunt trauma. One was a 10 1/2-month-old infant, the youngest yet reported with this condition to our knowledge. He required emergency repair because of increasing encroachment on respiratory function by the hernial contents during the early hours of observation. The second patient, a ten-year-old boy with an associated fractured femur, underwent successful repair of a diaphragmatic laceration that included the pericardium. In this case the approach via the abdomen, used to rule out associated intraperitoneal injuries, actually facilitated the repair, particularly that of the diaphragmatic pericardium.

Characterization of a 3H-arginine8-vasopressin binding site in the cingulate gyrus of the rat pup.

Autoradiographic analysis of 1, 8, 16 and 26-day-old rat brains showed 3H-arginine8-vasopressin (3H-AVP) binding to the cingulate gyrus-dorsal hippocampus (CG) only in the 8-day-old rat brain. Saturation analysis of CG membranes prepared from pups (7-10 days) and adults (90 days) revealed a small but significant increase in binding site concentration in adults compared to pups. However, the Kd of the 3H-AVP binding site increased significantly with age. The Kd of 3H-AVP binding to pup CG membranes was 0.9 +/- 0.1 nM, while the adult CG was 5.7 +/- 1.0 nM. The pharmacological specificity of 3H-AVP binding sites in the pup and adult CG was similar, but differed markedly from the profile observed in adult septal membranes. The primary specificity difference between the pup CG and septum was the reduced potency of certain V1 receptor antagonists. In competition experiments the CG binding site showed a reduced affinity for the V1 antagonist, [d(CH2)5, Tyr(Me)]AVP. This reduced affinity for the V1 antagonist was also documented autoradiographically using 3H-[d(CH2)5, Tyr(Me)]AVP. The data suggest that the 3H-AVP binding site expressed in the pup CG is not identical to the V1 type receptor present in the periphery and brain of the adult rat.

Evidence for glucocorticoid regulation of the rat vasopressin V1a receptor gene.

WRK-1 cells express vasopressin V1a receptors. Twenty-four-hour treatment of these cells with dexamethasone (DEX) resulted in an increase in [3H]AVP binding that was maximal at 12 h, and could be blocked by addition of RU 38486. The increases in [3H]AVP binding were paralleled by increases in V1a receptor mRNA. The in vivo effects of glucocorticoids (GCs) on V1a receptor binding in hepatic tissue were also investigated in adrenalectomized and hormone-replaced rats given either DEX or aldosterone (ALDO). DEX effectively increased V1a receptor binding site density whereas ALDO had no effect. The DEX effects on V1a receptor mRNA and binding strongly implicate glucocorticoids in the regulation of V1a receptor gene expression.

Conditioned c-Fos in mouse NTS during expression of a learned taste aversion depends on contextual cues.

c-Fos expression in the nucleus tractus solitarius (NTS) of the rat has been found to follow administration of a variety of pharmacologically diverse unconditioned stimuli (US), and it has been proposed that NTS is a critical structure in transduction of the US during taste aversion learning. Before conditioning, the conditioned stimulus (CS) taste does not induce c-Fos in NTS, but following pairing of the CS and US, subsequent CS presentation induces c-Fos in NTS. Although it has been suggested that the shift in the c-Fos response following conditioning represents a molecular correlate of taste aversion learning, i.e. the formerly neutral CS now predicts the toxicity associated with the US, the data presented here suggest a more cautious interpretation of c-Fos expression in NTS. In mice, post-conditioning c-Fos expression to the CS depends on contextual cues: when conditioning and testing occur in a novel environment, CS saccharin causes an increase in c-Fos expression, and when conditioning and testing occur in the home cage, CS saccharin produces a decrease in c-Fos expression relative to controls. Furthermore, we show that merely placing an animal into a novel environment is sufficient to drive c-Fos expression in NTS. These data suggest that c-Fos expression in NTS can be driven by a number of different stimuli and conditions, and that these responses may depend on context-dependent activation of forebrain structures shown to drive conditioned c-Fos expression in NTS.

c-Fos induction in response to a conditioned stimulus after single trial taste aversion learning.

Taste aversion conditioning is characterized by its prompt acquisition despite the introduction of long delays between CS (taste) and UCS (toxic drug). Although the dramatic changes in behavioral response to a taste after this conditioning are well documented, relatively little is known about the changes in neural activity that accompany this learning. c-Fos immunohistochemical staining was employed to define brain regions activated during the expression of a conditioned taste aversion (CTA). The present studies examined c-Fos immunoreactivity in the brains of rats after i.p. injection of LiCl or NaCl or after intraoral infusion of a saccharin CS. LiCl administration, a common unconditioned stimulus (UCS) in CTA experiments, was found to induce c-Fos protein in a number of brainstem regions, including the nucleus of the solitary tract (NTS), medial and lateral pontine parabrachial nucleus (PBN), and hypoglossal nucleus. Conditioned animals received a single pairing of the CS saccharin with the UCS LiCl, while controls were exposed to the CS saccharin but received non-contingent LiCl 24 h after saccharin exposure. Following saccharin re-exposure, conditioned animals showed patterns of neuronal activation to a taste which were similar to those activated by the UCS drug. Specifically, the pattern of c-Fos expression in conditioned animals was confined to the same region of the NTS which showed the most activation following the UCS LiCl. This pattern of activation was not evident in controls re-exposed to saccharin.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic treatment with vasopressin analogues alters affinity of vasopressin receptors in the septum and amygdala of the rat brain.

Accurel devices were used to administer AVP or AVP-antagonist into the lateral ventricle of the rat brain for 7 days. Neither AVP nor antagonist altered total binding site concentration in either septum or amygdala. However, treatment with antagonist caused a marked decrease in the affinity of the receptor for agonist in both the septum and amygdala.

c-Fos induction in response to taste stimuli previously paired with amphetamine or LiCl during taste aversion learning.

Amphetamine and lithium chloride (LiCl) are both effective unconditioned stimuli (USs) in the establishment of conditioned taste aversions (CTA) in the rat. However, the mechanism of action of these drugs is quite different with the area postrema and related emetic circuitry critical to the response to LiCl but not amphetamine. c-Fos immunohistochemistry was used to define brain regions activated during drug administration and during expression of a CTA using either amphetamine or LiCl as the US drug. Administration of LiCl induced dense c-Fos-like immunoreactivity (c-FLI) in the nucleus of the solitary tract (NTS) while amphetamine induced only light staining in this area. A conditioned stimulus (CS) saccharin solution paired with amphetamine, however, was associated with c-FLI in NTS in a pattern quite similar to that seen to a LiCl-paired CS. This suggests that the pattern of c-Fos expression to a taste CS after conditioning is characteristic of aversion conditioning, in general, and appears not to represent a matching of the conditioned response to specific unconditioned effects of the drug. To examine this conditioned response further, c-FLI to the aversive saccharin CS was compared to the response to quinine hydrochloride, which is innately aversive. Although behaviorally the animals' ingestive responses were quite similar, the saccharin CS induced significant elevations of c-FLI in NTS whereas the quinine did not. Thus, a taste which had become aversive by virtue of conditioning induced c-FLI expression in NTS while a taste which was inherently aversive did not.

Health-related quality of life using the SF-36 in patients with bipolar disorder compared with patients with chronic back pain and the general population.

BACKGROUND: The purpose of this study was to assess and compare the health-related quality of life of patients with bipolar disorder and chronic back pain and, in turn, to compare these results with those previously generated for the general population. METHODS: Subjects were patients with bipolar disorder (n=44), a comparison group of chronic back pain patients (n=30), and a population-based control sample (n=2,474). Health-related quality of life was assessed using the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36), a self-administered questionnaire in which lower scores are indicative of greater impairment. RESULTS: Patients with bipolar disorder had lower mean scores than the general population on all scales except Physical Functioning. Bipolar patients had significantly higher scores than chronic back pain patients in the categories of Physical Functioning, Role Limitations--Physical, Bodily Pain, and Social Function. There were no significant differences between bipolar disorder and chronic back pain groups in the Mental Health and Role Limitations - Emotional categories. LIMITATIONS: The results of the study are limited by the relatively small sample sizes of the bipolar and back pain patient groups. CONCLUSIONS: Patients with bipolar disorder had substantial impairment in health-related quality of life in comparison with the general population. Bipolar patients were less compromised in areas of physical and social functioning than chronic back pain patients but had similar impairment in mental health.

Pharmacological antagonism of tyrosine kinases and MAP kinase in brainstem blocks taste aversion learning in mice.

Although c-Fos induction in the brainstem is a reliable correlate of taste aversion learning and appears necessary for the encoding of the unconditioned stimulus, little is known about the intracellular signaling pathways in the brainstem that regulate c-Fos expression during taste aversion learning. Infusion of the tyrosine kinase inhibitor genistein and the MAP kinase kinase (MEK) inhibitor PD98059 into the fourth ventricle of mice potently blocks acquisition of a learned taste aversion. The unconditioned stimulus LiCl produces a rapid and robust phosphorylation of MAP kinase, as revealed by immunohistochemistry with an antibody specific to the dually phosphorylated active form of MAP kinase. This immunoreactivity is localized to the same region of the intermediate nucleus tractus solitarius in which we have shown large increases in c-Fos immunoreactive cells, suggesting that in at least a subset of these cells, MAP kinase activation may lead to c-fos induction.

Surgical revision for failed anterior cervical fusions. Articular pillar plating or anterior revision?

STUDY DESIGN: This retrospective study reviewed one surgeon's experience in treating symptomatic anterior cervical pseudarthrosis by three methods: anterior revisions, posterior revisions, and circumferential procedures. OBJECTIVES: To determine whether anterior revision and plating achieves a higher probability of radiographic fusion and better clinical outcomes compared with posterior fusion and articular pillar plating. The role of circumferential procedures was evaluated. SUMMARY OF BACKGROUND DATA: Management of cervical pseudarthrosis by a repeat anterior procedure requires a difficult dissection in a previously operated area, resection of a nonunion site, and regrafting. Because the incidence of failure is reported to be high, posterior cervical fusion has been proposed as a treatment for anterior pseudarthrosis. METHODS: The second author has performed 44 surgical revisions for symptomatic anterior cervical pseudarthrosis. Before this surgical revision, all patients had pain and a radiographic nonunion that was confirmed during surgery. The average follow-up period after the secondary procedure was 28 months with a range of 12-60 months. All patients (100%) were available for follow-up evaluation. Twenty patients had anterior pseudarthrosis repair and anterior plating. Seventeen patients underwent posterior cervical fusion and articular pillar plating. Seven patients had a circumferential repair with anterior revision and posterior articular pillar plating. RESULTS: All seven patients (100%) who had circumferential procedures achieved a solid radiographic fusion. Clinically, five patients felt better than before surgery, and two patients felt the same. Sixteen of 17 patients (94%) with posterior repairs achieved a solid fusion. Fourteen patients felt better; two patients felt the same, and one patient with a nonunion felt worse than before surgery. A solid fusion was obtained in only 45% of the patients after anterior repair alone. CONCLUSIONS: Posterior cervical articular pillar plating and fusion result in a higher probability of fusion than repeat anterior procedures, even with the addition of anterior plate stabilization. Posterior fusion and articular pillar plating, whether alone or part of a circumferential procedure, provides the added fixation required to successfully repair failed anterior cervical fusions.