Visualization of the location and level of pain in common wrist pathologies using color-coded heatmaps

BACKGROUND

Pain of the hand and wrist affects a large patient population. If the onset is unrelated to recent trauma, the first medical contact is rarely established with a specialized hand surgeon.

OBJECTIVE

The objective of this investigation was to (1) visualize the localization of hand pain using pain-related heatmaps in common wrist pathologies, (2) to test whether differences between these pathologies exist with regard to sociodemographic and pain-related aspects, and (3) to evaluate the major patient-reported complaints associated with the pathologies.

METHODS

This observational cross-sectional study included patients suffering from: thumb basal joint arthritis (CMC-1-OA), dorsal wrist ganglions, and TFCC tears. Patients marked the location of maximum pain projection on hand graphics depicting the outline of the palmar and dorsal hand. Color-graded frequency heat maps were generated for the wrist pathologies investigated. Daily life impairments were assessed and clustered into groups of functions/activities.

RESULTS

120 patients with a mean age of 44.3 years were investigated. The diagnostic groups showed significant differences regarding the level and location of pain, as well as daily life impairments. Patients with CMC-1-OA presented with increased pain levels compared to patients with dorsal wrist ganglions and TFCC tears. Daily life impairment was rated highest when household chores were adversely affected, and sport activities were symptomatic/painful. All groups showed significant skin surface pain projection, which was visualized in heatmaps. While general trends in pain localization were visible, pain levels were also reported distal/proximal and palmar/dorsal to the pathology.

CONCLUSIONS

Knowledge of main demographic parameters, pain projection, and degree of impairment in daily activities can help physicians to narrow differential diagnosis of wrist pain during first patient contact. Patients should then be referred to hand surgeons for specialist examination, to further differentiate the origin of the pain.

Multiphase flow modeling in centrifugal partition chromatography

The separation efficiency in Centrifugal Partition Chromatography (CPC) depends on selection of a suitable biphasic solvent system (distribution ratio, selectivity factor, sample solubility) and is influenced by hydrodynamics in the chambers. Especially the stationary phase retention, the interfacial area for mass transfer and the flow pattern (backmixing) are important parameters. Their relationship with physical properties, operating parameters and chamber geometry is not completely understood and predictions are hardly possible. Experimental flow visualization is expensive and two-dimensional only. Therefore we simulated the flow pattern using a volume-of-fluid (VOF) method, which was implemented in OpenFOAM®. For the three-dimensional simulation of a rotating FCPC®-chamber, gravitational centrifugal and Coriolis forces were added to the conservation equation. For experimental validation the flow pattern of different solvent systems was visualized with an optical measurement system. The amount of mobile phase in a chamber was calculated from gray scale values of videos recorded by an image processing routine in ImageJ®. To visualize the flow of the stationary phase polyethylene particles were used to perform a qualitative particle image velocimetry (PIV) analysis. We found a good agreement between flow patterns and velocity profiles of experiments and simulations. By using the model we found that increasing the chamber depth leads to higher specific interfacial area. Additionally a circular flow in the stationary phase was identified that lowers the interfacial area because it pushes the jet of mobile phase to the chamber wall. The Coriolis force alone gives the impulse for this behavior. As a result the model is easier to handle than experiments and allows 3D prediction of hydrodynamics in the chamber. Additionally it can be used for optimizing geometry and operating parameters for given physical properties of solvent systems.