Accuracy of tibial positioning in the frontal plane: a prospective study comparing conventional and innovative techniques in total knee arthroplasty.

BACKGROUND: Coronal alignment of the tibial component determines functional outcome and survival in total knee arthroplasty (TKA). Innovative techniques for tibial instrumentation have been developed to improve accuracy and reduce the rate of outliers. METHODS: In a prospective study, 300 patients were allocated to four different groups using a randomization process (two innovative and two conventional) techniques of tibial instrumentation (conventional: extramedullary, intramedullary; innovative: navigation and patient-specific instrumentation (PSI); n = 75 for each group). The aims were to reconstruct the medial proximal tibial angle (MPTA) to 90° and the mechanical tibio-femoral axis (mTFA) to 0°. Both angles were evaluated and compared between all groups three months after the surgery. Patients who presented with a postoperative mTFA > 3° were classified as outliers. RESULTS: The navigation and intramedullary technique both demonstrated that they were significantly more precise in reconstructing a neutral mTFA and MPTA compared to the other two techniques. The odd's ratio (OR) for producing outliers was highest for the PSI method (PSI OR = 5.5, p < 0.05; extramedullary positioning OR = 3.7, p > 0.05; intramedullary positioning OR = 1.7, p > 0.05; navigation OR = 0.04, p < 0.05). We could only observe significant differences between pre- and postoperative MPTA in the navigation and intramedullary group. The MPTA showed a significant negative correlation with the mTFA in all groups preoperatively and in the extramedullary, intramedullary and PSI postoperatively. CONCLUSION: The navigation and intramedullary instrumentation provided the precise positioning of the tibial component. Outliers were most common within the PSI and extramedullary technique. Optimal alignment is dependent on the technique of tibial instrumentation and tibial component positioning determines the accuracy in TKA since mTFA correlated with MPTA pre- and postoperatively.

Behavioural syndromes in fishes: a review with implications for ecology and fisheries management.

This review examines the contribution of research on fishes to the growing field of behavioural syndromes. Current knowledge of behavioural syndromes in fishes is reviewed with respect to five main axes of animal personality: (1) shyness-boldness, (2) exploration-avoidance, (3) activity, (4) aggressiveness and (5) sociability. Compared with other taxa, research on fishes has played a leading role in describing the shy-bold personality axis and has made innovative contributions to the study of the sociability dimension by incorporating social network theory. Fishes are virtually the only major taxon in which behavioural correlations have been compared between populations. This research has guided the field in examining how variation in selection regime may shape personality. Recent research on fishes has also made important strides in understanding genetic and neuroendocrine bases for behavioural syndromes using approaches involving artificial selection, genetic mapping, candidate gene and functional genomics. This work has illustrated consistent individual variation in highly complex neuroendocrine and gene expression pathways. In contrast, relatively little work on fishes has examined the ontogenetic stability of behavioural syndromes or their fitness consequences. Finally, adopting a behavioural syndrome framework in fisheries management issues including artificial propagation, habitat restoration and invasive species, may promote restoration success. Few studies, however, have examined the ecological relevance of behavioural syndromes in the field. Knowledge of how behavioural syndromes play out in the wild will be crucial to incorporating such a framework into management practices.

Behavioural type in newly emerged steelhead Oncorhynchus mykiss does not predict growth rate in a conventional hatchery rearing environment.

Behavioural assays were conducted on newly emerged steelhead Oncorhynchus mykiss to investigate the presence of behavioural syndromes and to determine whether behavioural type in young fish predicts growth rate in a conventional hatchery rearing environment. Individual fry were consistent in their position choice and activity behaviours across safe and unsafe contexts, as well as among assays conducted on different days. Position choice and activity behaviours, however, were not necessarily correlated to each other. Both behaviours predicted feeding rates during behavioural assays, but there was no relationship between fry behaviour and subsequent growth rate or survival during the first 3 months of hatchery rearing. These results support the hypothesis that selection in captivity may be relaxed with respect to behavioural type rather than directional, allowing for increased behavioural variance in domesticated populations. Modest magnitudes of correlations among fry behaviours, however, suggest that behavioural type may be unstable at the onset of the juvenile feeding stage.

State epidemiology programs and state epidemiologists: results of a national survey.

In 1983, the State Epidemiologists in 46 States completed a survey questionnaire describing the professional qualifications, training, and experience of State health department epidemiologists and the scope of participation by the State Epidemiologists and their staffs in public health programs. The survey identified 224 State health department epidemiologists (estimated U.S. ratio 1.1 per million population). A State health department epidemiologist was most often male (80 percent), frequently (57 percent) was a physician, had an average age of 41 years, and had worked as an epidemiologist for 9 years. Participation in public health programs (either by supervising or providing consultation) by the State Epidemiologists and their staffs focused mainly on general epidemiology and communicable disease programs; fewer than half had participated in programs relating to the health of women and children, chronic diseases, injuries, or in other programs directed towards preventing premature mortality. Recently, the State Epidemiologists have been trying to broaden their activities into these areas; however, the demands created by the acquired immunodeficiency syndrome (AIDS) will mostly likely slow this process. Based on the overall findings and collective experience, it was concluded that State health departments have too few epidemiologists to address the wide variety of important public health problems facing our communities. It was proposed that each State health department have at least four epidemiologists (including one or more physician epidemiologists) and at least one master's level biostatistician and that the epidemiologists-per-population ratio not be less than 1 per million.

Measles in rural Ohio county.

Between December 23, 1975, and March 31, 1976, 169 cases of measles were reported from Defiance County, Ohio, a small rural county in the northwest corner of the State. The outbreak spread from a single junior high school basketball player to eventually involve 19 of the 28 county schools. Among the affected schools, measles attack rates varied from 0.3-7.2% with a mean of 2.0%. A likely source of illness was determined for 160 of the 169 cases (95%). Intraschool transmission was most common, accounting for 97 of the 169 cases (57%) followed by sibling contact for 23 cases (14%). The pattern of measles spread was complex and would have been difficult to predict in advance even if surveillance systems reported each case the day it occurred. A control program held between February 2 and February 20, 1976, vaccinated 5145 of the 11,114 (46.3%) county schoolchildren. Forty-four cases of measles occurred 4 or more days following school clinics, 22 (50%) in children who requested measles vaccine at school clinics, 17 of whom were actually vaccinated. Most of the other cases occurred in students whose parents thought their children to be protected. Measles is a disease which spreads rapidly in a complex pattern over wide geographic areas. A control program vaccinating a large proportion of the children without definitive history of adequate vaccination or disease was apprently effective in curtailing the outbreak.

Health consequences of the snow disaster in Massachusetts, February 6, 1978.

On February 6, 1978, the largest New England blizzard of the century struck eastern Massachusetts. On request, four days later, the Center for Disease Control provided epidemiologic assistance. On-site disaster assistance provided decision-makers with immediate health surveillance information useful in helping the area return to normal. No outbreaks of infectious diseases and no significant increase in the number of deaths were observed in the week following the blizzard. Some of the deaths which occurred immediately after the blizzard might have been prevented if traffic had been banned earlier.

Epidemiology of subacute sclerosing panencephalitis.

The Subacute Sclerosing Panencephalitis Registry has compiled data from 453 instances of SSPE occurring in the United States from 1960 through 1976. The mean annual incidence during this period was 3.5 per 10 million persons under 20 years of age, 2.3 times higher for males than females, and 4.0 times higher for whites than blacks. Although the long-term pattern of incidence is unknown, the incidence of reported SSPE declined dramatically from 1970 to 1976. There are marked geographic variations of SSPE activity within the United States and also a higher incidence for children from farms (9.4 per 10 million persons under 20) compared with children from other rural domiciles (3.7 per 10 million), suburban children (2.9 per 10 million), and inner-city children (1.6 per 10 million). Available epidemiologic evidence suggests that some extrinsic factor, unrelated to measles or measles vaccine, is important in the pathogenesis of the disease.

Current status of mumps and mumps vaccine in the United States.

Reported mumps in the United States has declined to all-time low levels following the increasingly widespread use of mumps-virus vaccine. Mumps vaccine has proven safe and effective. Its incorporation into combined live-virus vaccines, especially measles-mumps-rubella, has made mumps vaccination a practical and economically feasible component of routine immunization activities. Because of the favorable experience to date with mumps vaccine and the associated drop in mumps morbidity and mortality, mumps control programs likely will receive increasing public health attention in the coming years.

Epidemiologic investigation of Marburg virus disease, Southern Africa, 1975.

During the first 10 days of February 1975, an Australian hitchhiker contracted Marburg virus disease while traveling through Rhodesia and died; the infection was subsequently passed to two other persons, who recovered. Investigators retraced the hitchhiker's steps in March and again in June 1975 in an effort to uncover the natural reservoir of the virus and determine how it was transmitted. Serum samples were collected from humans and animals wherever the patient had come in close contact with animals or insects. Arthropods of various types were collected in June 1975 and again in February 1976 for virus isolation attempts; at no time did the patient come in direct contact with nonhuman primates of any kind, or any other animals. Indirect contact with bats, monkeys, and birds through aerosols was possible, though at some distance. Direct contact with arthropods occurred throughout the trip; on several occasions it was notably severe. We believe that during this outbreak the first Marburg virus infection occurred by vector-borne transmission from an arthropod yet to be identified, and that patients 2 and 3 acquired the disease by exposure to the oropharyngeal secretions of patients 1 and 2, respectively. Studies are underway to identify the species of arthropod involved in this transmission.