Reliability of limb alignment measurement for high tibial osteotomy with a navigation system

Objective

High tibial osteotomy (HTO) is one treatment option for young and active patients with unicompartmental osteoarthritis. The success of this procedure substantially depends on the degree of correction of the mechanical axis. Computer-assisted navigation systems are believed to improve the precision of axis correction through intraoperative real-time monitoring. This study investigates the accuracy of limb alignment measurements with a navigation system on a cadaver specimen.

Materials and methods

The measurements were performed on a well-preserved cadaver specimen with a mechanical leg axis of 4° varus. Data was collected during the HTO workflow. Repeated serial measurements were undertaken by four different surgeons. After these measurements, different landmarks were deliberately set at the wrong place to examine the influence of mistakes during registration.

Results

There was a high intra-and interobserver reliability with a mean mechanical leg axis of 3.9° ± 0.7° and a mean error of 0.6°. The grossly incorrect placement of landmarks for knee and ankle center resulted in an incorrect mechanical leg axis of 1° valgus up to 10° varus.

Conclusion

The computer-assisted navigation system provided precise information about the mechanical leg axis, irrespective of the observer''s experience.     

Demografischer Wandel

Background

Demographic change not only affects patients with ophthalmological diseases but also ophthalmologists.

Objectives

The aim of this article is to evaluate the consequences of an aging society on health care provision. How can these challenges be overcome?

Material and methods

Evaluation of publications from the German Federal Statistical Office about the current and projected population, analysis of own studies about health care provision, utilization, and delivery as well as the presentation and discussion of regulatory and organizational conditions.

Results

There is a continuous increase in chronic and age-related diseases. At the same time the prevalence of multimorbidity and the number of patients dependent on long-term care is rising, leading to an increase in the demand for ophthalmological care. Regarding health care providers we observed a cutback in qualified ophthalmological personnel, especially for remote areas thus causing difficulties in providing adequate eye care to the population.

Conclusion

To deliver health care to a growing number of patients with a decreasing number of medical professionals is the major challenge of demographic change. This will have an enormous impact on ophthalmological health care in terms of maintaining high quality health services covering a nationwide area.     

Maurerschnüre

Background

Introduction of new working equipment or the modification of established working routines could induce new trauma mechanisms. In all of theses cases ophthalmologists are not only responsible for ocular treatment they also have to act as assessors. This might include legal aspects, e.g. to validate the circumstances of an accident.

Methods

We present a new trauma mechanism caused by a mason’s lacing cord which was fixed with nails. In addition to two case studies we collected experimental data (maximum tension and maximum elongation of various mason’s lacing cords) about the triggering event using standard test conditions.

Results

A tensile force of 96.2 N was needed to achieve maximum elongation of mason’s lacing cords. With a cord length of 5 m, an elongation of 0.09 m was enough to cause penetrating injuries (for 10 m cord length the critical elongation was 0.13 m). Under these conditions a nail could be accelerated to a velocity of 18 m/s. This may lead to open eyeball injuries with severe visual loss.

Conclusions

Nails fixed to elastic mason’s lacing cords are potential risk factors for occupational ocular injuries and severe loss of vision. Caution labels should be attached to the work equipment and proper eye protection should be used to prevent severe occupational ocular injuries.     

Atrial fibrillation burden during the post-implant period after crt using device-based diagnostics

AF Burden After CRT Implantation. AIMS: Cardiac resynchronization therapy (CRT) is increasingly used in congestive heart failure (CHF) patients (with cardiac dyssynchrony). In addition to delivering therapy, CRT devices offer a variety of diagnostic tools for continuous long-term monitoring of clinically relevant information (i.e., occurrence and duration of arrhythmia episodes). METHODS AND RESULTS: Eighty-four patients with drug-refractory CHF in NYHA-class II-IV received a CRT device. The response to CRT was assessed by determining NYHA class at baseline and at 3 months follow-up. Atrial fibrillation (AF) burden (defined as time of AF per day) was continuously measured by the device. A significant gradual reduction of AF burden (from 9.88 +/- 12.61 to 4.20 +/- 9.24 [hours/day]) and number of patients experiencing AF episodes (from 26 to 13) were observed during CRT. CONCLUSIONS: (1) Diagnostic features for long-term monitoring of physiological variables provide useful information on the state and course of AF and may improve disease management. (2) AF burden reduces over time during the first 3 months after CRT implantation.     

Interaction of Serotonin Transporter Gene-Linked Polymorphic Region and Stressful Life Events Predicts Cortisol Stress Response

There has been significant controversy whether stressful life events (SLEs) experienced over the lifespan may elevate the risk of depression in individuals who are homozygous for the short (S) allele of the repeat length polymorphism (5-HTTLPR) in the regulatory region of the serotonin transporter gene (SLC6A4), compared with individuals homozygous for the long (L) allele. On the basis of the hypothesis that age may be a critical variable, by which such a gene-by-environment interaction may be present in younger adults, but not in older adults and in children, aim of this study was to investigate the role of 5-HTTLPR and SLEs on the endocrine stress response in multiple age cohorts. A total of 115 children (8–12 years), 106 younger adults (18–31 years), and 99 older adults (54–68 years) were subjected to the Trier Social Stress Test (TSST) and structured interviews on SLEs. The TSST induced significant endocrine stress responses in all groups. There was a main effect of genotype in younger and older adults with individuals homozygous for the more active L allele showing a significantly larger cortisol response to the TSST than individuals carrying at least one of the low-expressing S alleles. As predicted, there was a significant interaction of 5-HTTLPR genotype and SLEs, but this interaction was only significant in younger adults and only when the measured SLEs had occurred during the first 5 years of life, suggesting that both age and the specific type of SLE has a role in whether a significant gene–environment interaction is observed.     

Children under stress - COMT genotype and stressful life events predict cortisol increase in an acute social stress paradigm

Dopamine and norepinephrine are key regulators of cognitive and affective processes. The enzyme catechol-O-methyltransferase (COMT) catabolizes catecholamines and the COMT Val158Met polymorphism has been linked to several neuropsychiatric variables. Additionally, stressful life events (SLEs) contribute substantially to affective processes. We used the stress-induced activation of the hypothalamic-pituitary-adrenal axis to investigate the effects of COMT and SLEs on the cortisol response in 119 healthy children (8-12 yr). Saliva cortisol was measured during and after the Trier Social Stress Test for Children. SLEs were assessed with a standardized interview with one of the children's parents. Linear regression analysis revealed a significant effect for COMT, with Met allele carriers showing a higher cortisol response (β=0.300, p=0.001). In turn, more SLEs lead to a less pronounced cortisol increase (β=-0.192, p=0.029) probably indicating increased resilience. Our results further underscore the essential and differential role of genetic variation and environmental factors on stress responsivity.