Regional pain block

Regional pain blocks are widely used in medicine. The term ‘block’ once referred to reducing or stopping pain, above all by blocking the transmission of pain signals along the nerve pathways, but it has since been extended to other structures and procedures. Although not entirely accurate medically, the term ‘block’ is understood by both doctors and patients, because the relief that follows this kind of treatment is significant and the medicine acts quickly and effectively. The more accurate term is ‘injection’, so injections into joints, tendons and ligaments and injections around nerves are among the core interventional procedures in physiatry, rheumatology and orthopaedics. The large number of pathological processes and the accessibility and size of the joints and other structures are the deciding factors in choosing the medicine and the route of the procedure. Conditions such as osteoarthritis, rheumatoid, reactive and psoriatic arthritis, ankylosing spondylitis and crystal arthropathies affect almost all the structures of the knee. We would single out osteoarthritis as the most common disease, one that has an inflammatory as well as a degenerative component. Whether a single medicine or a combination is used depends on the predominant pathological process and on the indications and contraindications. Diagnostic ultrasound allows various interventional procedures to be carried out more precisely, such as injections, blocks, instillations, tendon fenestration, dry needling and acupuncture; various medicines can also be given, such as corticosteroids, anaesthetics, hyaluronic acid, whole blood, stem cells and many others.

Application techniques depend on the location and on the knowledge and experience of the doctor, who chooses the medicine and the technique based on the clinical status, laboratory findings and imaging; we can increase the accuracy of the technique with diagnostic ultrasound. The specific structure we want to treat, such as cartilage, synovium, bone, an enthesis or a nerve, influences the choice of medicine. When to use instillation techniques, and how to place them in the context of the continuum of disease progression and overlap with other diseases, is a subject of ongoing research. The term ‘medicine’ is used here in a broader sense, because individual preparations are registered differently and some belong to, or are registered in, different groups. The injection site must be prepared to the highest medical standards, so that the medicine can be given as accurately as possible with the lowest risk of side effects. Instillation and injection are preceded or followed by other procedures, such as aspiration and the analysis and differentiation of the aspirate. Monitoring the effect and the clinical response is important when deciding whether to repeat the treatment, and the response often varies from person to person.