## 1 Introduction  
Recently, there has been radical progress in diagnostic technologies; on the other hand, applications based on already known technologies are constantly emerging in the world of medicine and rehabilitation. There are various diagnostic imaging methods used for the assessment of muscosceletal disorders (MSDs), both for diagnosis and monitoring, namely plain radiographs (X-rays, XR), dual-energy X-ray absorptiometry (DXA), ultrasonography, arthropod tomography (CT), or magnetic resonance imaging (MRI), all of which image the morphological structures. In recent years, more and more efforts have been made to investigate the causes of MSDs and take preventive action. Considerable support is provided by supplementary tests assessing the neuromuscular function, not only the structure, including electromyography [1] and infrared thermography [2]. Imaging may be used to confirm a clinical diagnosis, or its verification when there is clinical doubt [3].  
The musculoskeletal system is structurally diverse, comprising bones, muscles, joints, cartilage, ligaments, tendons, and burase. Each of these structures can be temporarily or permanently damaged or affected by many disorders. Musculoskeletal diseases and injuries are among the most disabling diseases affecting humans and have become a major public health problem worldwide, while being a leading cause of work disability, sickness absenteeism from work, and loss of productivity [4]. According to the World Health Organization (WHO), about 1.71 billion people worldwide suffer from musculoskeletal disorders that result in severe and prolonged pain [5, 6].  
Musculoskeletal conditions include acute and chronic diseases that affect joints (osteoarthritis, chronic polyarthitis, rheumatoid arthritis, psoriatic arthritis, gout, and ankylosing spondylitis), bones (osteoporosis, osteopenia, and osteomalacia osteonecrosis), muscles (dystrophy, myasthenia gravis, and sarcopenia, tendonitis), and the spine (low back and neck pain), as well as multiple body areas or systems with symptoms (regional and widespread pain disorders, inflammatory diseases, connective tissue diseases, and vasculitis) affecting the musculoskeletal system.  
In patients with MSDs, an accurate differential diagnosis is a key to selecting appropriate treatments; moreover, monitoring of treatment effects, apart from subjective patient assessment, should also be based on objective diagnostic methods that are affordable and do not burden the patient. Research conducted in recent years has shown that infrared thermography (IRT) is useful in medical diagnostics, and also in the case of MSDs [7]. One of the arguments in favor of conducting research on the use of IRT to diagnose MSDs may be the possibility of lowering the costs of diagnosis and treatment, and minimizing radiation harmful to patients. Thermography can be useful in early diagnosis and for monitoring the effectiveness of rehabilitation because of its high sensitivity in several situations: to assess pain during muscle injuries, inflammation in injuries and in degenerative and rheumatic changes, occupational disorders, ischemic areas, excessive friction in dentures, joint overload, asymmetry of muscle tone and activity, and various motor diseases.  
In this article, the authors discuss the medical applications of IRT for musculoskeletal system diseases, with particular emphasis on its usefulness in assessing the therapeutic effects of physical procedures used in rehabilitation. The authors provide guidelines and recommendations for those interested.