1. Investigación

Ultrasonographic signs of tendinopathies are an increase in thickness, loss of alignment in collagen fibers and the presence of neovascularization. Nevertheless, analysis of intratendinous vascular resistance (IVR) can be more useful for understanding the physiological state of the tissue. To show thermal, echotextural, and Doppler signal differences in athletes with patellar tendinopathy and controls. Twenty-six athletes with patellar tendinopathy (PT) participants (30.1 years; SD = 9.0 years) and 27 asymptomatic athletes (23.3 years; SD = 5.38 years) were evaluated with thermographic and Doppler ultrasonography (DS). Area of Doppler signals (DS), echotextural parameters (echointensity and echovariation) and IVR were determined by image analysis. The statistical analysis was performed by Bayesian methods and the results were showed by Bayes Factor (BF10: probability of alternative hypothesis over null hypothesis), and Credibility intervals (CrI) of the effect. The absolute differences of temperature (TD) were clearly greater (BF10 = 19) in the tendinopathy group (patients) than in controls. Regarding temperature differences between the affected and healthy limb, strong evidence was found (BF10 = 14) for a higher temperature (effect = 0.53°C; 95% CrI = 0.15°C–0.95°C) and very strong for reduced IVR compared (BF10 = 71) (effect = −0.67; 95% CrI = −1.10 to 0.25). The differences in area of DS (BF10 = 266) and EV (BF10 = 266) were higher in tendinopathy group. TD showed a moderate positive correlation with VISA-P scores (tau-B = .29; 95% CrI = .04–.51) and strong correlation with IVR (r = −.553; 95%CrI = −.75 to .18). Athletes with patellar tendinopathy showed a more pronounced thermal difference, a larger area of Doppler signal, a lower IVR and a moderately higher echovariaton than controls. The correlation between temperature changes and IVR might be related with the coexistence of degenerative and inflammatory process in PT.

Thermography is an imaging technique that records the infrared radiation of the skin with a potential to detect asymmetries in body temperature and relating them to pathologies or risk of injury. However, the location of landmarks and region of interest (ROI) can influence the recording process. In this study we describe the reliability of a method to select the ROI without modifying the original thermogram over 68 thermograms (17 participants) of patellar tendon with an infrared camera (softwareOptris 450PI). The width-height, X-Y axis and mean temperature of the ROI was measured by two examiners.All the lower limits of the Intraclass Correlation Coeficiente (CCI) were over 0.84 without biases. The skin temperature was similar for both intra-examiner (F1,33=0.488; p=0.490) and inter-examiner (F1,33=0.011; p=0.917). The mean differences were 0.006ºC (Limit of agreement (LoA): -0.10 to 0.10), The differences between examiners were 0.001 ºC (LoA: -0.13 to 0.13). All temperature differences were <0.25ºC. The method used has very good intra and inter-examiner reliability and reproducibility and the influence on the skin temperature is negligible. It will be of interest to extend the study to ascertain the reliability using different thermal cameras and software, which could increase the strength of the method.

The aim of this study was to determine the intra- and inter-rater reliability of a new semi-automatic image analysis method for quantification of the shape of the Doppler signal and the intratendinous vascular resistance in patellar tendinopathy. Thirty athletes (27.4 y, standard deviation = 8.57 y) with patellar intratendinous vascularity were included in a cross-sectional study (42 tendons analyzed). The intratendinous blood flow was assessed with power Doppler and ImageJ (Version 1.50b, National Institutes of Health, Bethesda, MD, USA) quantification software over a manually selected region of interest. Two blinded observers performed the analysis of the Doppler signal (vascular resistance) and shape descriptors (number of signals, pixel intensity, area, perimeter, major diameter, minor diameter, circularity and solidity). The intraclass correlation coefficient (ICC) was calculated, and the Bland-Altman mean of differences (MoD) and 95% limits of agreement (LoA) were determined. Also, small real differences (SRDs) and the standard error of measurement (SEM) were calculated. Intra-rater reliability was at a maximum for area (ICC = 0.999, 95% confidence interval [CI] = 0.998-0.999) and at a minimum for solidity (ICC = 0.782, 95% CI: 0.682-0.853). The MoD and 95% LoA were very low, and the relative SRD and SEM were below 5.3% and 2%, respectively. The inter-rater reliability was the maximum for area (ICC = 0.993, 95% CI = 0.989-0.996) and the minimum for circularity (ICC = 0.73; 95% CI=0.611-0.817). The MoD and 95% LoA were low, with the SRD and SEM below 6% and 2.2%. The proposed quantitative method for studying the intratendinous Doppler signal in the patellar tendon is reliable and reproducible.