The influence of asymmetric quadriceps loading on patellar tracking — An in vitro study

BackgroundIn patients with anterior knee pain and patellar instability, a specific training of the quadriceps muscle – especially the vastus medialis – is often recommended, although the practicability is discussed controversially and the proof of a measurable clinical effect is difficult. Therefore, this in vitro study investigates the influence of asymmetric muscle loading on the motion of the human patella.MethodsSeven human knee specimens were tested in a specially developed knee simulator. During simulated weight-bearing knee flexion, the kinematics of tibia, femur and patella were measured using an ultrasound motion capture system. The quadriceps forces were controlled to achieve a constant ankle force over the whole flexion range which is assumed to represent almost physiological loading. Three different force distributions of the quadriceps were tested — a central, equally distributed load as well as mainly lateral and medial loads.ResultsA significant influence of different quadriceps force distributions was found for patellar tilt around a proximodistal axis (up to 1.7°) and patellar rotation around an anteroposterior axis (up to 3.8°) with respect to the femur. Interestingly, the patellar mediolateral shift was influenced only marginally (< 1.5 mm).ConclusionsSpecific muscle training might help patients with patellofemoral pain and cartilage damage by a slight modification of the kinematics, but we could show that even highly asymmetric quadriceps loads only led to a small alteration of the mediolateral shift in case of a physiologic anatomy of the trochlear groove.     

Disability and quality of life in individuals with postpolio syndrome

Purpose : The purpose of the study is to investigate disability and quality of life in individuals with the characteristic symptoms of postpolio syndrome. Method : Disability is assessed by means of the self-report activities of daily living instrument, and quality of life by means of Kaasa's questionnaire and the quality of life profile. Results : The 39 subjects have on average lived with polio sequelae for 52 years. Their main difficulties are with moving, lifting and carrying. This means restricted mobility, sedentary activities and a need to prioritize. Half of them feel that polio has lessened their possibilities in life, and a quarter have still not accepted the limitations polio has involved. Nevertheless the majority report a high level of psychosocial well-being, and almost a quarter say that living with polio has meant personal development and strength. We found a significant correlation between on the one hand disability with regard to ambulation, arm strength and finger strength on the self-report ADL, and on the other hand the number of negative problems on the quality of life profile (0.33-0.45). Conclusion : The latter instrument needs further testing before its validity can be determined with certainty.     

Psychotic Experiences,Childhood Trauma,and Alcohol-Related Self-Efficacy in a Nonpsychiatric Sample of Individuals in Alcohol Dependence Treatment: A Pilot Study

There is a substantial co-occurrence between alcohol dependence and psychiatric symptoms. Moreover, research suggests that such symptoms, including psychotic experiences, are continuously distributed in the population. There is a lack of research concerning psychotic symptoms in otherwise non-psychiatric populations with alcohol dependence. The aim of this study was to investigate the prevalence of psychotic symptoms in this population, and to relate this to childhood trauma and management of alcohol dependence. From a population with alcohol dependence two sub-groups were extracted, with low and high levels of psychotic experiences respectively. These were compared concerning childhood trauma and management of dependence using ANOVA, and the resulting model was examined using binary logistic regression. There was a sub-group of 14,3% of the population with elevated levels of psychotic experiences. This group displayed higher degree of self-reported childhood trauma as well as difficulties in managing alcohol dependence, when compared to a sub-group with low levels of psychotic experiences. There may be a substantial sub-group in the otherwise non-psychiatric population with alcohol dependence, with significant difficulties concerning psychotic symptoms, trauma and management of dependence, where anxiety may have a mediating function. If so, this group calls for broader assessment and treatment than standard alcohol interventions.     

Work-related skin and airway symptoms among Swedish dentists rarely cause sick leave or change of professional career

Dentistry usually is 'wet work' with risk of damage to the skin barrier, and the hands may be exposed to skin irritants and contact-sensitizing substances used in dental materials or gloves. Airway irritants may also be present. This study assessed the consequences of work-related skin and airway symptoms among dentists in terms of contact with health authorities, sick leave, or changes in the professional career. A questionnaire on these factors was answered by more than 3000 Swedish dentists. Only 6% of the respondents had consulted a physician, although 22% had noted work-related skin symptoms. In 2% the skin symptoms had caused sick leave, and about 2% had reported their skin symptoms as an occupational disease. Two per cent had consulted a physician owing to work-related airway symptoms, which is a minor part of the 13% who had experienced such symptoms when in contact with dental materials. Twenty-five dentists (<1%)had been on sick leave because of work-related airway symptoms. Only 19 dentists reported change of activities or occupation owing to work-related skin or airway symptoms, and in most cases these symptoms only contributed to their decision. In summary, whereas sick leave in dentists because of musculoskeletal problems may be common, the present study shows that this is not the case for workrelated skin or airway symptoms, and such symptoms seldom affect the dentists' professional career.     

Economic repercussions of fisheries-induced evolution

Fish stocks experiencing high fishing mortality show a tendency to mature earlier and at a smaller size, which may have a genetic component and therefore long-lasting economic and biological effects. To date, the economic effects of such ecoevolutionary dynamics have not been empirically investigated. Using 70 y of data, we develop a bioeconomic model for Northeast Arctic cod to compare the economic yield in a model in which life-history traits can vary only through phenotypic plasticity with a model in which, in addition, genetic changes can occur. We find that evolutionary changes toward faster growth and earlier maturation occur consistently even if a stock is optimally managed. However, if a stock is managed optimally, the evolutionary changes actually increase economic yield because faster growth and earlier maturation raise the stock’s productivity. The optimal fishing mortality is almost identical for the evolutionary and nonevolutionary model and substantially lower than what it has been historically. Therefore, the costs of ignoring evolution under optimal management regimes are negligible. However, if fishing mortality is as high as it has been historically, evolutionary changes may result in economic losses, but only if the fishery is selecting for medium-sized individuals. Because evolution facilitates growth, the fish are younger and still immature when they are susceptible to getting caught, which outweighs the increase in productivity due to fish spawning at an earlier age.