Joint pain: characteristics, and its 5 most common causes.

We explain the main causes of joint pain and the way in which this discomfort presents itself.

A joint is an anatomical structure that allows the union between two bones or between a bone and a cartilage. When we think of joints, those of the shoulders or knees come to mind, diarthroses (synovial) that bring two bony structures into contact and allow a wide range of movements in all spatial axes.

However, not all articular elements fall into this category. Of the 360 joints, some 86 are located in the skull, connecting flat bones with practically no mobility. In total, the body has 76 joints in the spine and pelvis, 66 in the thorax, 6 in the throat, 32 in each arm and 31 in each leg. All of them are necessary for the maintenance of the shape and posture of the human being or, failing that, for the development of movements.

Unfortunately, sometimes joints can fail for various reasons, causing a greater or lesser disability in the affected person. Without going any further, the World Health Organization estimates that 1710 million people suffer from at least one musculoskeletal disorder around the globe, making these conditions the first universal cause of disability (at least in high-income countries). If you want to know all about joint pain and its possible causes, read on.read on.

What is joint pain?

Among the more than 150 musculoskeletal disorders that can affect the human being, low back pain is the most common of all. It affects more than 568 million people worldwide, making it the leading cause of occupational disability in 160 different countries. However, there are many more disorders that can affect walking and locomotion, and many of them manifest themselves in the form of joint pain.

For its part, joint pain or arthralgia is considered a symptom in the clinical setting, rather than a typical disease.. Frequently, this discomfort arises from the dysfunction of external structures, such as muscles, tendons or ligaments. In other cases, mineral deposits (such as calcium pyrophosphate) may occur in the joint synovium and cause damage to the joint itself.

According to the Global Year Against Musculoskeletal Pain, pain usually occurs during physical activities and decreases during rest or postural maintenance.. An increased sensitivity to pain in the joint area can be explained by the following mechanisms:

• Peripheral sensitization: characterized by an amplified response in nociceptors, receptors that pick up and send noxious stimuli to the brain. This change is induced by inflammatory mediators, such as cytokines and prostaglandins.
• Central sensitization: a pathological process that affects the central nervous system (CNS) and consists of a reduction of the pain threshold. It is accompanied by the exaggerated perception of uncomfortable stimuli (hyperalgesia) and the occurrence of pain to apparently innocuous stimuli (allodynia).

In addition, joint pain can be acute (transient) or chronic (of continuous onset, over months or years).. This discomfort is usually localized to the affected joint(s), but sometimes it is also possible to notice discomfort referred to the leg or arms. The pain, in turn, leads to motor limitation, lameness, physical impairment and loss of strength, either in the short or long term.

Possible causes of joint pain

As we have said, joint pain is a symptom, and therefore a consequence of an underlying process, more or less serious. Here are some clinical entities that can manifest with arthralgia at different levels. Do not miss it.

1. Ankylosing spondylitis

Ankylosing spondylitis (AS) is a chronic form of arthritis. The cause of the disease is unknown, but genetics seems to play an essential role in its development: most of the diseased persons (90%) are positive for the leukocyte antigen HLA-B27, associated with various pathologies of an autoimmune nature.

This condition affects almost 2% of the population in some high-income countries, and is thought to be due to a is thought to be due to a misguided immune response by the immune system, especially the lymphocytes of the immune system.especially CD8 T lymphocytes. However, it has not yet been demonstrated that it is due to a mechanism of self-antigen recognition (an event by which lymphocytes see normal tissues of the human body as pathogens).

2. Osteoarthritis

Osteoarthritis (OA) is the most common joint disorder in the world. Over the years, the articular cartilage wears down, causing the bones to rub together and decreasing their functionality over time. over time. It is estimated that 70 to 90% of patients over 75 years of age have some radiological sign of osteoarthritis, so it is a pathology completely related to aging and age.

Osteoarthritis is what we usually refer to when we think of rheumatism: an elderly person with swollen, hooked hands who finds it difficult to perform daily tasks. However, it should be noted that the term "rheumatism" actually encompasses more than 200 clinical entities of a rheumatic nature, all with joint and/or tendon wear and tear in common.

3. Rheumatoid arthritis

Rheumatoid arthritis can be confused with osteoarthritis, but the etiology is not the same. On this occasion, the cells of the autoimmune system seem to start attacking joint tissue without any specific biological meaningprobably due to the primary action and activation of exogenous triggers (such as viruses or bacteria).

This results in chronic inflammatory responses (usually in the joints of hands and fingers), which gradually damage ligaments, joints and tendons in the active focus of immune cells. It presents with long-lasting morning stiffness, a very important differential feature.It presents with long-lasting morning stiffness, a very important differential feature to distinguish rheumatoid arthritis from osteoarthritis.

4. Fibromyalgia

A chronic condition that goes beyond the joints, because in this case ligaments, muscles and muscles are also affected. ligaments, muscles and tendons are also affected.. Interestingly, this clinical picture can manifest itself very similarly to joint pain, but the problematic focus is actually in the muscles, not in the joints.

It is a much more common condition than it seems, affecting 2 to 6% of the world's population, especially women. Fibromyalgia develops chronically and the symptoms are very general: fatigue (90%), sleep disorders (80%), pain in one or more muscle, joint or ligament areas (100%) and even depression or chronic anxiety (25%). On this occasion, special emphasis is placed on muscular discomfort.

5. Other conditions that cause joint pain

Many conditions can cause joint pain beyond those already described. For example, sometimes bacteria from a primary infectious focus can travel into the synovial fluid of the joint and progress into it, an event known as infectious arthritis. The patient shows local swelling, inability to move the affected area and even fever and chills.

On the other hand, a cancerous tumor can also endanger the structures of the joints, as in the case of synovial sarcoma.as in the case of synovial sarcoma. Interestingly, this type of malignant neoplasm is more common in children and young adults, although it can also occur in the elderly population. There is also the likelihood that a bone tumor (osteosarcoma) may spread to a joint area, which also causes joint pain.

Summary

In summary, joint pain is multifactorial. As it is a symptom and not a disease, there can be many causes, from cancers to autoimmune pathologies, infections, mechanical injuries, metabolic disorders and many more. In any case, we stress again that osteoarthritis is the most common type of joint pain, something relatively normal associated with the passage of time and age.

Even so, the fact that something is normal does not mean that a patient should live with it. In the clinical setting there is a maxim: living with pain and adapting to it is never a possibility. With physiotherapy, occupational therapy, drugs (analgesics, Anti-Inflammatory drugs and immunosuppressants) and psychological therapy, chronic pain can be addressed.