Osteoarthritis overview

# Overview
Osteoarthritis / Osteoarthrosis (OA, also known as degenerative joint disease, degenerative arthritis, arthrosis or in more colloquial terms "wear and tear") is the most common form of arthritis, caused by wearing of the cartilage that covers and cushions joint spaces. As the cartilage wears away, the patient may experience pain described as "weight-bearing" whenever walking and standing. Due to the movement limitations caused by pain, regional muscles may experience atrophy. Ligaments may become laxer as well due to this. OA is derived from the Greek word "osteo", meaning "of the bone", "arthro", meaning "joint", and "itis", meaning inflammation, although inflammation is not a common finding in this regard. OA possesses a great degree of variability in disease onset, progression, and severity. OA is characterized by a variety of structural and functional impairments occurring in an involved joint. Destruction, degeneration, articular cartilage loss, and even the soft tissue involvement are the main pathological process of this disease. It can be diagnosed through radiographic evaluations. Moreover, clinical sign and symptoms are helpful in the final diagnosis of this disease. OA can be defined radiologically, clinically, or pathologically, with radiographic OA being considered as the reference standard. The symptoms that are consistently associated with OA are joint pain, stiffness, swelling, and limitation of joint function. Few individuals who present these symptoms may not demonstrate radiographic OA. However, others confirmed to have OA using radiographic techniques may not present with clinical manifestations of the disease. These unique characteristics have made it difficult to identify the underlying mechanisms contributing to the disease as well as the treatments for reducing the incidence and severity of the disease. In addition, the stimuli that may initiate the processes associated with OA are multifactorial and include occupational and non-occupational (e.g., genetics, obesity, age, etc.) factors. OA affects nearly 43 million patients in United States and almost 15% of the world population, accounting for 25% of visits to primary care physicians, and half of all NSAID (Non-Steroidal Anti-Inflammatory Drugs) prescriptions. It is estimated that 80% of the population will have radiographic evidence of OA by age 65, although only 60% of those will be There is no recent discovery of a cure for OA, as cartilage has not been induced to regenerate. However, if OA is caused by cartilage damage (for example as a result of an injury) Autologous Chondrocyte Implantation may be a possible treatment. Other treatments are with NSAIDs, local injections of glucocorticoid or hyaluronan, and in severe cases, with joint replacement surgery. Many physicians have also reported good pain relief by treating ligaments (which is responsible for a bone to bone connection) with Prolotherapy. Clinical trials employing tissue-engineering methods have demonstrated regeneration of cartilage in damaged knees, including those that have progressed to osteoarthritis. Furthermore, in January 2007, Johns Hopkins University was offering to license a technology of this kind, listing several clinical competitors in its market analysis. Osteoarthritis is capable of influencing any joint in the human body; meanwhile, the most commonly affected joints are the knee and hip joints given that the degree of weight bearing required of these joints is immense. Other joints, such as the distal interphalangeal joints of the fingers and shoulder joints are also commonly affected as well. The economic burden of OA for United States economy is more than $60 billion per year; which has more economic pressure than rheumatoid arthritis. This cost can be considered into two subgroups: the medical related costs and the lost expediency of patients at work 

# Historical Perspective
The earliest descriptions of OA were provided by Heberden and Haygarth in the 19th century. In the 1930s and 1940s, Dr. Stecher showed that there were two forms of OA: idiopathic and post-traumatic.  In the 1950s, the connection between Heberdens nodes and large joint OA were revealed by Kellgren and Moore. In this regard, the first x-ray grading system for OA was developed by Jonas Kellgren and John Lawrence in the 1950s. Surgical management of OA was developed in the 1960s by Drs. Charnley and McKee 

# Classification
Osteoarthritis is radiographically classified depending on the degree of joint involvement. The Kellgren-Lawrence is a common method to classify the severity of OA in the knee using five different grades. This classification was proposed by Kellgren et al. in 1957 and was then accepted by WHO in 1961 ...

# Pathophysiology
Osteoarthritis (OA) is a well-known degenerative joint disease influencing millions of people worldwide. Osteoarthritis is a complex disease caused by changes in the tissues' homeostasis of articular cartilages and subchondral bones. The cell/extracellular matrix (ECM) and their interactions play an important role in the pathophysiology of articular cartilage and the occurrence of Osteoarthritis. Consequently, the main feature of OA is that after this process is involved, the articular cartilages of the involved joint no longer will have a normal acting system because the destruction of the articular cartilages can no longer act as shock absorber. abnormal integrin expression alters cell/ECM signaling and modifies chondrocyte synthesis, with the following imbalance of destructive cytokines over regulatory factors. IL-1, TNF-alpha and other pro-catabolic cytokines activate the enzymatic degradation of cartilage matrix and are not counterbalanced by adequate synthesis of inhibitors. The main enzymes involved in ECM breakdown are metalloproteinases (MMPs), which are sequentially activated by an amplifying cascade. MMP activity is partially inhibited by the tissue inhibitors of MMPs (TIMPs), whose synthesis is low compared with MMP production in OA cartilage.

# Causes
Osteoarthritis (OA) is a result of a variety of disorders that lead to structural and functional failure in involved joints. Osteoarthritis, traditionally, has been considered as a disease specifically related to articular cartilage. Presently, it's been proven that OA influencing the whole joint system consisted of capsule, and synovium, subchondral bone, cartilage, menisci, ligaments, and periarticular muscle.

# Differentiating Osteoarthritis overview from Other Diseases
OA must be differentiated from other diseases that cause joint impairment and  other related signs and symptoms such as Rheumatoid arthritis, Gout, Joint tuberculosis.

# Epidemiology and Demographics
OA is one of the most frequent diagnoses and is the leading cause of disability among the adult population in the USA. According to the National Health and Nutrition Examination Survey (NHANES), more than 26 million people in the USA were diagnosed with different forms of OA. The National Health Interview Survey (NHIS) reported that the 46.4 million Americans and 21.6% of Americans adults were diagnosed with arthritis. OA can involve any joint, but knees, hips, hands, are most common sites for this involvement.

# Risk Factors
Osteoarthritis is a multifactorial disease and the interactions between systemic and local factors play important role in development and prognosis of OA.

# Screening
Routine screening for osteoarthritis is not indicated unless the patient is symptomatic.

# Natural History, Complications, and Prognosis

## Natural History
The orthopedic surgeons are frequently asked by their patients regarding the final outcome and the prognosis of their diseased joint/joints caused by OA. Information about the natural history of OA is very important for upcoming determinations and planning for patients management. A small number of studies are available studied the role of the radiographic findings, joint congruence, or even the daily life activity on the OA progression.

## Complications
OA is a leading cause of morbidity having significant effects on patients life and the health care system and even it could cause heavy economic burden. According to the American Academy of Orthopedic Surgeons report movement limitation are found in 80% of adults diagnosed with osteoarthritis. Meanwhile, 25% of these patients facing difficulties in their of daily living activities. 11% of them need personal care assistance and 14% required help with their routine needs.

## Prognosis
Most osteoarthritis cases do stabilize. Some osteoarthritis cases progress. A small number of osteoarthritis patients improve spontaneously.

# Diagnosis

## Diagnostic Criteria
There is no specific signs and symptoms of osteoarthritis (OA) diagnosis. Although, osteoarthritis may be diagnosed based on several elements such as patients age, past medical history, and available symptoms. Osteoarthritis of the major joints is diagnosed using a combination of patients past medical history, physical examination, and variety of lab tests including imaging studies such as X-ray.

## History and Symptoms
Patients' past medical history is the most useful tool for the osteoarthritis diagnosis.

## Physical Examination
A physical examination following the medical history is necessary for medical doctors to reach an exact diagnosis. In OA, loss or limited range of motion in specific joints, swelling, tenderness, and bony growths in the surrounding area are the most important keys in physical examination of OA cases.

## Laboratory Findings
If the OA diagnosis is in doubt, laboratory tests are used to help doctors get a confirmation regarding a suspected diagnosis of osteoarthritis.

## Imaging Findings
X-Ray and CT-Scan are the most common tools used in this regard.

## Other Diagnostic Studies

# Treatment

## Medical Therapy
Nonpharmacologic therapy is consisted of physical therapy and specific type of physical exercises, bracing and splinting. Physical therapy results in short-term pain reduction, and improvement in physical function in the diseased joint to preserve its the ability for daily tasks like walking, dressing, and even bathing. Having moderate activity strengthens the muscles around the diseased joint and this reduces stress and increases the stability of the joint system. On the other hand, resting is another important healing factor in OA. Bracing and splinting as other methods help to support painful or unstable joints. Using a cane can help decrease the weight pressure in diseased hip or knee, but it should be used on the contralateral side of the affected joint.

## Surgery
Surgical interventions in OA cases should be considered when the symptoms have no response to the first line treatments because osteoarthritis symptoms can be successfully managed through non-surgical care. For some, however, if they are experiencing severe joint damage, extreme pain, or very restricted mobility, surgery may be a viable option in this regard. The main indication criteria for surgery in OA is pain and disabilities despite the medical treatments. The most common and effective surgical intervention are arthroscopic surgery, osteotomy, and arthroplasty (total joint replacement). Considering the potential benefits of surgery like pain relief, improved movement, increased patients status, and actual disease prognosis, it should be remembered that any surgical interventions have risks. Meanwhile, overweight patients or patients with co-morbidities have higher risk of operation. The current joint prostheses have an expected functional usage for almost 15 to 20 years.

## Prevention
Primary prevention for OA include :
- Weight loss
- Physical activity
- Injury prevention
- Control infectious disease
- Avoidance of trauma on the joint
- Omega-3 fatty acid