Dr. med. Thomas Ambacher
In addition to the inflammatory reaction of the joint, injuries and wear processes also trigger reflexive muscular tension, which can lead to painful trigger points. Local hyperemia develops in the area of the trigger points, which can also be visualized by thermography. Muscular hyperemia without structural damage cannot be visualized by other common diagnostic methods (sonography, MRI).
Reference points of thermography are the corresponding anatomical structures on the opposite side. The absolute temperature values are not meaningful. Therefore, the absence of symptoms of the muscle and joint structures on the opposite side is a limiting precondition of thermography diagnostics.
A color scale is used to visualize the temperature conditions (white-warm, blue-cold). In addition, the skin temperature can be determined directly via the camera display at defined points with an accuracy of 0.3 degrees. For detailed evaluation of the maximum, minimum and average temperature of specific circumscribed skin areas, the use of special software is recommended. Data is transferred from the camera to the PC via a USB connection (Fig. 1).
The advantages of thermography examination are:
- non-invasive
- no radiation exposure
- can be repeated as often as required
- inexpensive
- immediate availability of the measured values
- comprehensible visualization of the severity of the inflammation for the patient
- examination of the entire functional chain
- progress controls for the evaluation of the treatment effect
Sources of error can result from radiating heat sources in the environment (e.g. sonography device, PC), tilting of the camera and local treatments/ manipulations of the skin. As already mentioned, the limiting precondition is the intact, symptom-free anatomical structure on the opposite side. The examination should be performed in front of a neutral surface at a distance of about one meter perpendicular to the body surface. Thermography is a side-effect-free, non-invasive, immediately available diagnostic method that can be repeated as often as desired to monitor the progress of treatment.
Thermography is used as an additional diagnostic procedure as part of the usual standard examination of the joint, with the focus on assessing the severity of an inflammatory reaction. As a rule, the examination procedure is such that after history taking, physical examination and sonography, thermography is used before we arrange for X-ray diagnostics or MRI examination. Isolated thermography cannot detect anatomical tissue damage, but only its reactive inflammation. Therefore, a correlation between direct anatomical imaging and thermography is always required.
Keywords: thermography, joint pain, inflammation
Inflammatory processes are usually reactions of the body to overloads, wear processes and injuries. The inflammatory response is a sensible physiological reaction that leads to the healing of tissue damage. The increase in blood flow leads to an increase in temperature in the tissue with inflammatory changes, which can be detected with thermography if the temperature increase at the skin surface exceeds a difference of 0.3 degrees compared to the unaffected opposite side.