Arthroscopy vs. MRI for a detailed assessment of cartilage disease in osteoarthritis: diagnostic value of MRI in clinical practice

<p>Abstract</p> <p>Background</p> <p>In patients with osteoarthritis, a detailed assessment of degenerative cartilage disease is important to recommend adequate treatment. Using a representative sample of patients, this study investigated whether MRI is reliable for a detailed cartilage assessment in patients with osteoarthritis of the knee.</p> <p>Methods</p> <p>In a cross sectional-study as a part of a retrospective case-control study, 36 patients (mean age 53.1 years) with clinically relevant osteoarthritis received standardized MRI (sag. T1-TSE, cor. STIR-TSE, trans. fat-suppressed PD-TSE, sag. fat-suppressed PD-TSE, Siemens Magnetom Avanto syngo MR B 15) on a 1.5 Tesla unit. Within a maximum of three months later, arthroscopic grading of the articular surfaces was performed. MRI grading by two blinded observers was compared to arthroscopic findings. Diagnostic values as well as intra- and inter-observer values were assessed.</p> <p>Results</p> <p>Inter-observer agreement between readers 1 and 2 was good (kappa = 0.65) within all compartments. Intra-observer agreement comparing MRI grading to arthroscopic grading showed moderate to good values for readers 1 and 2 (kappa = 0.50 and 0.62, respectively), the poorest being within the patellofemoral joint (kappa = 0.32 and 0.52). Sensitivities were relatively low at all grades, particularly for grade 3 cartilage lesions. A tendency to underestimate cartilage disorders on MR images was not noticed.</p> <p>Conclusions</p> <p>According to our results, the use of MRI for precise grading of the cartilage in osteoarthritis is limited. Even if the practical benefit of MRI in pretreatment diagnostics is unequivocal, a diagnostic arthroscopy is of outstanding value when a grading of the cartilage is crucial for a definitive decision regarding therapeutic options in patients with osteoarthritis.</p

Does thermoregulatory behavior maximize reproductive fitness of natural isolates of Caenorhabditis elegans?

BACKGROUND: A central premise of physiological ecology is that an animal's preferred body temperature should correspond closely with the temperature maximizing performance and Darwinian fitness. Testing this co-adaptational hypothesis has been problematic for several reasons. First, reproductive fitness is the appropriate measure, but is difficult to measure in most animals. Second, no single fitness measure applies to all demographic situations, complicating interpretations. Here we test the co-adaptation hypothesis by studying an organism (Caenorhabditis elegans) in which both fitness and thermal preference can be reliably measured.RESULTS: We find that natural isolates of C. elegans display a range of mean thermal preferences and also vary in their thermal sensitivities for fitness. Hot-seeking isolates CB4854 and CB4857 prefer temperatures that favor population growth rate (r), whereas the cold-seeking isolate CB4856 prefers temperatures that favor Lifetime Reproductive Success (LRS).CONCLUSIONS: Correlations between fitness and thermal preference in natural isolates of C. elegans are driven primarily by isolate-specific differences in thermal preference. If these differences are the result of natural selection, then this suggests that the appropriate measure of fitness for use in evolutionary ecology studies might differ even within species, depending on the unique ecological and evolutionary history of each population.</p