Joint instability is a condition characterized by the loss of normal joint function and increased risk of joint injury due to impaired integrity of the supporting structures, such as ligaments, muscles, or cartilage. This can result in excessive movement or laxity within the joint, leading to decreased stability and increased susceptibility to dislocations or subluxations. Joint instability may cause pain, swelling, and limited range of motion, and it can significantly impact a person's mobility and quality of life. It is often caused by trauma, degenerative conditions, or congenital abnormalities and may require medical intervention, such as physical therapy, bracing, or surgery, to restore joint stability.

Pronation is a term used in the medical field, particularly in the study of human biomechanics and orthopedics. It refers to the normal motion that occurs in the subtalar joint of the foot, which allows the foot to adapt to various surfaces and absorb shock during walking or running.

During pronation, the arch of the foot collapses, and the heel rolls inward, causing the forefoot to rotate outward. This motion helps distribute the forces of impact evenly across the foot and lower limb, reducing stress on individual structures and providing stability during weight-bearing activities.

However, excessive pronation can lead to biomechanical issues and increase the risk of injuries such as plantar fasciitis, shin splints, and knee pain. Proper assessment and management of foot mechanics, including orthotics or physical therapy interventions, may be necessary to address excessive pronation and related conditions.

Supination is a term used in the medical field, particularly in the study of anatomy and orthopedics. It refers to the external rotation of the forearm so that the palm faces forward or upward. This motion allows for the hand to be in a position to perform actions such as lifting, holding, or throwing objects. It's also used to describe the movement of the foot when it rolls outward, which is important for normal walking and running gait. Abnormal supination can lead to issues with mobility and pain in the affected limb.

The wrist joint, also known as the radiocarpal joint, is a condyloid joint that connects the distal end of the radius bone in the forearm to the proximal row of carpal bones in the hand (scaphoid, lunate, and triquetral bones). It allows for flexion, extension, radial deviation, and ulnar deviation movements of the hand. The wrist joint is surrounded by a capsule and reinforced by several ligaments that provide stability and strength to the joint.

The medial collateral ligament (MCL) of the knee is a band-like structure located on the inner side of the knee joint. It connects the end of the femur (thighbone) to the top of the tibia (shinbone) and helps stabilize the knee by controlling side-to-side movement and preventing excessive separation of the bones. The MCL provides resistance to valgus force, which is a pushing or pulling force that attempts to push the bones apart in a direction away from the midline of the body. MCL injuries often occur due to direct impact to the outer knee or sudden changes in direction that strain the ligament.

Articular ligaments, also known as fibrous ligaments, are bands of dense, fibrous connective tissue that connect and stabilize bones to each other at joints. They help to limit the range of motion of a joint and provide support, preventing excessive movement that could cause injury. Articular ligaments are composed mainly of collagen fibers arranged in a parallel pattern, making them strong and flexible. They have limited blood supply and few nerve endings, which makes them less prone to injury but also slower to heal if damaged. Examples of articular ligaments include the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) in the knee joint, and the medial collateral ligament (MCL) and lateral collateral ligament (LCL) in the elbow joint.

The term "stifle" is commonly used in veterinary medicine to refer to the joint in the leg of animals, specifically the knee joint in quadrupeds such as dogs and horses. In human anatomy, this joint is called the patellofemoral joint or knee joint. The stifle is a complex joint made up of several bones, including the femur, tibia, and patella (kneecap), as well as various ligaments, tendons, and cartilage that provide stability and support. Injuries or diseases affecting the stifle can cause lameness, pain, and decreased mobility in animals.

The knee joint, also known as the tibiofemoral joint, is the largest and one of the most complex joints in the human body. It is a synovial joint that connects the thighbone (femur) to the shinbone (tibia). The patella (kneecap), which is a sesamoid bone, is located in front of the knee joint and helps in the extension of the leg.

The knee joint is made up of three articulations: the femorotibial joint between the femur and tibia, the femoropatellar joint between the femur and patella, and the tibiofibular joint between the tibia and fibula. These articulations are surrounded by a fibrous capsule that encloses the synovial membrane, which secretes synovial fluid to lubricate the joint.

The knee joint is stabilized by several ligaments, including the medial and lateral collateral ligaments, which provide stability to the sides of the joint, and the anterior and posterior cruciate ligaments, which prevent excessive forward and backward movement of the tibia relative to the femur. The menisci, which are C-shaped fibrocartilaginous structures located between the femoral condyles and tibial plateaus, also help to stabilize the joint by absorbing shock and distributing weight evenly across the articular surfaces.

The knee joint allows for flexion, extension, and a small amount of rotation, making it essential for activities such as walking, running, jumping, and sitting.

Osteoarthritis (OA) is a type of joint disease that is characterized by the breakdown and eventual loss of cartilage - the tissue that cushions the ends of bones where they meet in the joints. This breakdown can cause the bones to rub against each other, causing pain, stiffness, and loss of mobility. OA can occur in any joint, but it most commonly affects the hands, knees, hips, and spine. It is often associated with aging and can be caused or worsened by obesity, injury, or overuse.

The medical definition of osteoarthritis is: "a degenerative, non-inflammatory joint disease characterized by the loss of articular cartilage, bone remodeling, and the formation of osteophytes (bone spurs). It is often associated with pain, stiffness, and decreased range of motion in the affected joint."

A joint is the location at which two or more bones make contact. They are constructed to allow movement and provide support and stability to the body during motion. Joints can be classified in several ways, including structure, function, and the type of tissue that forms them. The three main types of joints based on structure are fibrous (or fixed), cartilaginous, and synovial (or diarthrosis). Fibrous joints do not have a cavity and have limited movement, while cartilaginous joints allow for some movement and are connected by cartilage. Synovial joints, the most common and most movable type, have a space between the articular surfaces containing synovial fluid, which reduces friction and wear. Examples of synovial joints include hinge, pivot, ball-and-socket, saddle, and condyloid joints.

Articular Range of Motion (AROM) is a term used in physiotherapy and orthopedics to describe the amount of movement available in a joint, measured in degrees of a circle. It refers to the range through which synovial joints can actively move without causing pain or injury. AROM is assessed by measuring the degree of motion achieved by active muscle contraction, as opposed to passive range of motion (PROM), where the movement is generated by an external force.

Assessment of AROM is important in evaluating a patient's functional ability and progress, planning treatment interventions, and determining return to normal activities or sports participation. It is also used to identify any restrictions in joint mobility that may be due to injury, disease, or surgery, and to monitor the effectiveness of rehabilitation programs.

The Anterior Cruciate Ligament (ACL) is a major stabilizing ligament in the knee. It is one of the four strong bands of tissue that connect the bones of the knee joint together. The ACL runs diagonally through the middle of the knee and helps to control the back and forth motion of the knee, as well as provide stability to the knee joint. Injuries to the ACL often occur during sports or physical activities that involve sudden stops, changes in direction, or awkward landings.

Articular cartilage is the smooth, white tissue that covers the ends of bones where they come together to form joints. It provides a cushion between bones and allows for smooth movement by reducing friction. Articular cartilage also absorbs shock and distributes loads evenly across the joint, protecting the bones from damage. It is avascular, meaning it does not have its own blood supply, and relies on the surrounding synovial fluid for nutrients. Over time, articular cartilage can wear down or become damaged due to injury or disease, leading to conditions such as osteoarthritis.

Genomic instability is a term used in genetics and molecular biology to describe a state of increased susceptibility to genetic changes or mutations in the genome. It can be defined as a condition where the integrity and stability of the genome are compromised, leading to an increased rate of DNA alterations such as point mutations, insertions, deletions, and chromosomal rearrangements.

Genomic instability is a hallmark of cancer cells and can also be observed in various other diseases, including genetic disorders and aging. It can arise due to defects in the DNA repair mechanisms, telomere maintenance, epigenetic regulation, or chromosome segregation during cell division. These defects can result from inherited genetic mutations, acquired somatic mutations, exposure to environmental mutagens, or age-related degenerative changes.

Genomic instability is a significant factor in the development and progression of cancer as it promotes the accumulation of oncogenic mutations that contribute to tumor initiation, growth, and metastasis. Therefore, understanding the mechanisms underlying genomic instability is crucial for developing effective strategies for cancer prevention, diagnosis, and treatment.

Chromosomal instability is a term used in genetics to describe a type of genetic alteration where there are abnormalities in the number or structure of chromosomes within cells. Chromosomes are thread-like structures that contain our genetic material, and they usually exist in pairs in the nucleus of a cell.

Chromosomal instability can arise due to various factors, including errors in DNA replication or repair, problems during cell division, or exposure to environmental mutagens. This instability can lead to an increased frequency of chromosomal abnormalities, such as deletions, duplications, translocations, or changes in the number of chromosomes.

Chromosomal instability is associated with several human diseases, including cancer. In cancer cells, chromosomal instability can contribute to tumor heterogeneity, drug resistance, and disease progression. It is also observed in certain genetic disorders, such as Down syndrome, where an extra copy of chromosome 21 is present, and in some rare inherited syndromes, such as Bloom syndrome and Fanconi anemia, which are characterized by a high risk of cancer and other health problems.

Joint diseases is a broad term that refers to various conditions affecting the joints, including but not limited to:

1. Osteoarthritis (OA): A degenerative joint disease characterized by the breakdown of cartilage and underlying bone, leading to pain, stiffness, and potential loss of function.
2. Rheumatoid Arthritis (RA): An autoimmune disorder causing inflammation in the synovial membrane lining the joints, resulting in swelling, pain, and joint damage if left untreated.
3. Infectious Arthritis: Joint inflammation caused by bacterial, viral, or fungal infections that spread through the bloodstream or directly enter the joint space.
4. Gout: A type of arthritis resulting from the buildup of uric acid crystals in the joints, typically affecting the big toe and characterized by sudden attacks of severe pain, redness, and swelling.
5. Psoriatic Arthritis (PsA): An inflammatory joint disease associated with psoriasis, causing symptoms such as pain, stiffness, and swelling in the joints and surrounding tissues.
6. Juvenile Idiopathic Arthritis (JIA): A group of chronic arthritis conditions affecting children, characterized by joint inflammation, pain, and stiffness.
7. Ankylosing Spondylitis: A form of arthritis primarily affecting the spine, causing inflammation, pain, and potential fusion of spinal vertebrae.
8. Bursitis: Inflammation of the fluid-filled sacs (bursae) that cushion joints, leading to pain and swelling.
9. Tendinitis: Inflammation or degeneration of tendons, which connect muscles to bones, often resulting in pain and stiffness near joints.

These conditions can impact the function and mobility of affected joints, causing discomfort and limiting daily activities. Proper diagnosis and treatment are essential for managing joint diseases and preserving joint health.

Microsatellite instability (MSI) is a genetic phenomenon characterized by alterations in the number of repeat units in microsatellites, which are short repetitive DNA sequences distributed throughout the genome. MSI arises due to defects in the DNA mismatch repair system, leading to accumulation of errors during DNA replication and cell division.

This condition is often associated with certain types of cancer, such as colorectal, endometrial, and gastric cancers. The presence of MSI in tumors may indicate a better prognosis and potential response to immunotherapy, particularly those targeting PD-1 or PD-L1 pathways.

MSI is typically determined through molecular testing, which compares the length of microsatellites in normal and tumor DNA samples. A high level of instability, known as MSI-High (MSI-H), is indicative of a dysfunctional mismatch repair system and increased likelihood of cancer development.

A finger joint, also known as an articulation, is the point where two bones in a finger connect and allow for movement. The majority of finger joints are classified as hinge joints, permitting flexion and extension movements. These joints consist of several components:

1. Articular cartilage: Smooth tissue that covers the ends of the bones, enabling smooth movement and protecting the bones from friction.
2. Joint capsule: A fibrous sac enclosing the joint, providing stability and producing synovial fluid for lubrication.
3. Synovial membrane: Lines the inner surface of the joint capsule and produces synovial fluid to lubricate the joint.
4. Volar plate (palmar ligament): A strong band of tissue located on the palm side of the joint, preventing excessive extension and maintaining alignment.
5. Collateral ligaments: Two bands of tissue located on each side of the joint, providing lateral stability and limiting radial and ulnar deviation.
6. Flexor tendons: Tendons that attach to the bones on the palmar side of the finger joints, facilitating flexion movements.
7. Extensor tendons: Tendons that attach to the bones on the dorsal side of the finger joints, enabling extension movements.

Finger joints are essential for hand function and enable activities such as grasping, holding, writing, and manipulating objects.

The ankle joint, also known as the talocrural joint, is the articulation between the bones of the lower leg (tibia and fibula) and the talus bone in the foot. It is a synovial hinge joint that allows for dorsiflexion and plantarflexion movements, which are essential for walking, running, and jumping. The ankle joint is reinforced by strong ligaments on both sides to provide stability during these movements.

The hip joint, also known as the coxal joint, is a ball-and-socket type synovial joint that connects the femur (thigh bone) to the pelvis. The "ball" is the head of the femur, while the "socket" is the acetabulum, a concave surface on the pelvic bone.

The hip joint is surrounded by a strong fibrous capsule and is reinforced by several ligaments, including the iliofemoral, ischiofemoral, and pubofemoral ligaments. The joint allows for flexion, extension, abduction, adduction, medial and lateral rotation, and circumduction movements, making it one of the most mobile joints in the body.

The hip joint is also supported by various muscles, including the gluteus maximus, gluteus medius, gluteus minimus, iliopsoas, and other hip flexors and extensors. These muscles provide stability and strength to the joint, allowing for weight-bearing activities such as walking, running, and jumping.

The tarsal joints are a series of articulations in the foot that involve the bones of the hindfoot and midfoot. There are three main tarsal joints:

1. Talocrural joint (also known as the ankle joint): This is the joint between the talus bone of the lower leg and the tibia and fibula bones of the lower leg, as well as the calcaneus bone of the foot. It allows for dorsiflexion and plantarflexion movements of the foot.
2. Subtalar joint: This is the joint between the talus bone and the calcaneus bone. It allows for inversion and eversion movements of the foot.
3. Tarsometatarsal joints (also known as the Lisfranc joint): These are the joints between the tarsal bones of the midfoot and the metatarsal bones of the forefoot. They allow for flexion, extension, abduction, and adduction movements of the foot.

These joints play an important role in the stability and mobility of the foot, allowing for various movements during activities such as walking, running, and jumping.

A joint capsule is the fibrous sac that encloses a synovial joint, which is a type of joint characterized by the presence of a cavity filled with synovial fluid. The joint capsule provides stability and strength to the joint, while also allowing for a range of motion. It consists of two layers: an outer fibrous layer and an inner synovial membrane. The fibrous layer is made up of dense connective tissue that helps to stabilize the joint, while the synovial membrane produces synovial fluid, which lubricates the joint and reduces friction during movement.

Microsatellite repeats, also known as short tandem repeats (STRs), are repetitive DNA sequences made up of units of 1-6 base pairs that are repeated in a head-to-tail manner. These repeats are spread throughout the human genome and are highly polymorphic, meaning they can have different numbers of repeat units in different individuals.

Microsatellites are useful as genetic markers because of their high degree of variability. They are commonly used in forensic science to identify individuals, in genealogy to trace ancestry, and in medical research to study genetic diseases and disorders. Mutations in microsatellite repeats have been associated with various neurological conditions, including Huntington's disease and fragile X syndrome.

The shoulder joint, also known as the glenohumeral joint, is the most mobile joint in the human body. It is a ball and socket synovial joint that connects the head of the humerus (upper arm bone) to the glenoid cavity of the scapula (shoulder blade). The shoulder joint allows for a wide range of movements including flexion, extension, abduction, adduction, internal rotation, and external rotation. It is surrounded by a group of muscles and tendons known as the rotator cuff that provide stability and enable smooth movement of the joint.

The sacroiliac (SI) joint is the joint that connects the iliac bone (part of the pelvis) and the sacrum (the triangular bone at the base of the spine). There are two sacroiliac joints, one on each side of the spine. The primary function of these joints is to absorb shock between the upper body and lower body and distribute the weight of the upper body to the lower body. They also provide a small amount of movement to allow for flexibility when walking or running. The SI joints are supported and stabilized by strong ligaments, muscles, and bones.

Temporomandibular Joint Disorders (TMD) refer to a group of conditions that cause pain and dysfunction in the temporomandibular joint (TMJ) and the muscles that control jaw movement. The TMJ is the hinge joint that connects the lower jaw (mandible) to the skull (temporal bone) in front of the ear. It allows for movements required for activities such as eating, speaking, and yawning.

TMD can result from various causes, including:

1. Muscle tension or spasm due to clenching or grinding teeth (bruxism), stress, or jaw misalignment
2. Dislocation or injury of the TMJ disc, which is a small piece of cartilage that acts as a cushion between the bones in the joint
3. Arthritis or other degenerative conditions affecting the TMJ
4. Bite problems (malocclusion) leading to abnormal stress on the TMJ and its surrounding muscles
5. Stress, which can exacerbate existing TMD symptoms by causing muscle tension

Symptoms of Temporomandibular Joint Disorders may include:
- Pain or tenderness in the jaw, face, neck, or shoulders
- Limited jaw movement or locking of the jaw
- Clicking, popping, or grating sounds when moving the jaw
- Headaches, earaches, or dizziness
- Difficulty chewing or biting
- Swelling on the side of the face

Treatment for TMD varies depending on the severity and cause of the condition. It may include self-care measures (like eating soft foods, avoiding extreme jaw movements, and applying heat or cold packs), physical therapy, medications (such as muscle relaxants, pain relievers, or anti-inflammatory drugs), dental work (including bite adjustments or orthodontic treatment), or even surgery in severe cases.

The metatarsophalangeal (MTP) joint is the joint in the foot where the metatarsal bones of the foot (the long bones behind the toes) connect with the proximal phalanges of the toes. It's a synovial joint, which means it's surrounded by a capsule containing synovial fluid to allow for smooth movement. The MTP joint is responsible for allowing the flexion and extension movements of the toes, and is important for maintaining balance and pushing off during walking and running. Issues with the MTP joint can lead to conditions such as hallux valgus (bunions) or hammertoe.

A joint prosthesis, also known as an artificial joint or a replacement joint, is a surgical implant used to replace all or part of a damaged or diseased joint. The most common types of joint prostheses are total hip replacements and total knee replacements. These prostheses typically consist of a combination of metal, plastic, and ceramic components that are designed to replicate the movement and function of a natural joint.

Joint prostheses are usually recommended for patients who have severe joint pain or mobility issues that cannot be adequately managed with other treatments such as physical therapy, medication, or lifestyle changes. The goal of joint replacement surgery is to relieve pain, improve joint function, and enhance the patient's quality of life.

Joint prostheses are typically made from materials such as titanium, cobalt-chrome alloys, stainless steel, polyethylene plastic, and ceramics. The choice of material depends on a variety of factors, including the patient's age, activity level, weight, and overall health.

While joint replacement surgery is generally safe and effective, there are risks associated with any surgical procedure, including infection, blood clots, implant loosening or failure, and nerve damage. Patients who undergo joint replacement surgery typically require several weeks of rehabilitation and physical therapy to regain strength and mobility in the affected joint.

"Foot joints" is a general term that refers to the various articulations or connections between the bones in the foot. There are several joints in the foot, including:

1. The ankle joint (tibiotalar joint): This is the joint between the tibia and fibula bones of the lower leg and the talus bone of the foot.
2. The subtalar joint (talocalcaneal joint): This is the joint between the talus bone and the calcaneus (heel) bone.
3. The calcaneocuboid joint: This is the joint between the calcaneus bone and the cuboid bone, which is one of the bones in the midfoot.
4. The tarsometatarsal joints (Lisfranc joint): These are the joints that connect the tarsal bones in the midfoot to the metatarsal bones in the forefoot.
5. The metatarsophalangeal joints: These are the joints between the metatarsal bones and the phalanges (toes) in the forefoot.
6. The interphalangeal joints: These are the joints between the phalanges within each toe.

Each of these foot joints plays a specific role in supporting the foot, absorbing shock, and allowing for movement and flexibility during walking and other activities.

Biomechanics is the application of mechanical laws to living structures and systems, particularly in the field of medicine and healthcare. A biomechanical phenomenon refers to a observable event or occurrence that involves the interaction of biological tissues or systems with mechanical forces. These phenomena can be studied at various levels, from the molecular and cellular level to the tissue, organ, and whole-body level.

Examples of biomechanical phenomena include:

1. The way that bones and muscles work together to produce movement (known as joint kinematics).
2. The mechanical behavior of biological tissues such as bone, cartilage, tendons, and ligaments under various loads and stresses.
3. The response of cells and tissues to mechanical stimuli, such as the way that bone tissue adapts to changes in loading conditions (known as Wolff's law).
4. The biomechanics of injury and disease processes, such as the mechanisms of joint injury or the development of osteoarthritis.
5. The use of mechanical devices and interventions to treat medical conditions, such as orthopedic implants or assistive devices for mobility impairments.

Understanding biomechanical phenomena is essential for developing effective treatments and prevention strategies for a wide range of medical conditions, from musculoskeletal injuries to neurological disorders.

The temporomandibular joint (TMJ) disc is a small, thin piece of fibrocartilaginous tissue located within the TMJ, which is the joint that connects the mandible (jawbone) to the temporal bone of the skull. The disc acts as a cushion and allows for smooth movement of the jaw during activities such as eating, speaking, and yawning. It divides the joint into two compartments: the upper and lower compartments.

The TMJ disc is composed of several types of tissue, including collagen fibers, elastin fibers, and a small number of cells called fibroblasts. The disc's unique structure allows it to withstand the forces generated during jaw movement and helps to distribute these forces evenly across the joint.

The TMJ disc can become damaged or displaced due to various factors such as trauma, teeth grinding (bruxism), or degenerative joint diseases like osteoarthritis. This can lead to temporomandibular disorders (TMDs) characterized by pain, stiffness, and limited jaw movement.

The acromioclavicular (AC) joint is the joint located between the acromion process of the scapula (shoulder blade) and the clavicle (collarbone). It allows for a small amount of movement between these two bones and participates in shoulder motion. Injuries to this joint, such as AC joint separations or sprains, are common and can occur due to falls, direct blows, or repetitive motions that cause the ligaments that support the AC joint to become stretched or torn.

A mutation is a permanent change in the DNA sequence of an organism's genome. Mutations can occur spontaneously or be caused by environmental factors such as exposure to radiation, chemicals, or viruses. They may have various effects on the organism, ranging from benign to harmful, depending on where they occur and whether they alter the function of essential proteins. In some cases, mutations can increase an individual's susceptibility to certain diseases or disorders, while in others, they may confer a survival advantage. Mutations are the driving force behind evolution, as they introduce new genetic variability into populations, which can then be acted upon by natural selection.

A dislocation is a condition in which a bone slips out of its normal position in a joint. This can happen as a result of trauma or injury, such as a fall or direct blow to the body. Dislocations can cause pain, swelling, and limited mobility in the affected area. In some cases, a dislocation may also damage surrounding tissues, such as ligaments, tendons, and nerves.

Dislocations are typically treated by reducing the dislocation, which means putting the bone back into its normal position. This is usually done with the help of medication to relieve pain and relaxation techniques to help the person stay still during the reduction. In some cases, surgery may be necessary to repair damaged tissues or if the dislocation cannot be reduced through other methods. After the dislocation has been reduced, the joint may be immobilized with a splint or sling to allow it to heal properly.

It is important to seek medical attention promptly if you suspect that you have a dislocation. If left untreated, a dislocation can lead to further complications, such as joint instability and chronic pain.

DNA repair is the process by which cells identify and correct damage to the DNA molecules that encode their genome. DNA can be damaged by a variety of internal and external factors, such as radiation, chemicals, and metabolic byproducts. If left unrepaired, this damage can lead to mutations, which may in turn lead to cancer and other diseases.

There are several different mechanisms for repairing DNA damage, including:

1. Base excision repair (BER): This process repairs damage to a single base in the DNA molecule. An enzyme called a glycosylase removes the damaged base, leaving a gap that is then filled in by other enzymes.
2. Nucleotide excision repair (NER): This process repairs more severe damage, such as bulky adducts or crosslinks between the two strands of the DNA molecule. An enzyme cuts out a section of the damaged DNA, and the gap is then filled in by other enzymes.
3. Mismatch repair (MMR): This process repairs errors that occur during DNA replication, such as mismatched bases or small insertions or deletions. Specialized enzymes recognize the error and remove a section of the newly synthesized strand, which is then replaced by new nucleotides.
4. Double-strand break repair (DSBR): This process repairs breaks in both strands of the DNA molecule. There are two main pathways for DSBR: non-homologous end joining (NHEJ) and homologous recombination (HR). NHEJ directly rejoins the broken ends, while HR uses a template from a sister chromatid to repair the break.

Overall, DNA repair is a crucial process that helps maintain genome stability and prevent the development of diseases caused by genetic mutations.

Rheumatoid arthritis (RA) is a systemic autoimmune disease that primarily affects the joints. It is characterized by persistent inflammation, synovial hyperplasia, and subsequent damage to the articular cartilage and bone. The immune system mistakenly attacks the body's own tissues, specifically targeting the synovial membrane lining the joint capsule. This results in swelling, pain, warmth, and stiffness in affected joints, often most severely in the hands and feet.

RA can also have extra-articular manifestations, affecting other organs such as the lungs, heart, skin, eyes, and blood vessels. The exact cause of RA remains unknown, but it is believed to involve a complex interplay between genetic susceptibility and environmental triggers. Early diagnosis and treatment are crucial in managing rheumatoid arthritis to prevent joint damage, disability, and systemic complications.