Stenosing tenosynovitis is most commonly caused by overuse from chronic repetitive activities using the hand or the involved finger. Examples include work activities (e.g., computer use, materials handling) or recreational activities (e.g., knitting, golf, racket sports). Carpenters who use hammers suffer from this as well as those who continuously grip wood or other materials when cutting them due to having to use your hands as a clamp to hold things in place.

Primary stenosing tenosynovitis can be idiopathic, occurring in middle age women more frequently than in men, but can present also in infancy.

Secondary stenosing tenosynovitis can be caused by disease or entities that cause connective tissue disorders including the following:

- Rheumatoid arthritis and psoriatic arthritis—therefore the clinician must assess the hands for rheumatologic deformities.

- Gout

- Diabetes mellitus

- Amyloidosis

- Systemic lupus erythematosus

Others causes may include the following:

- Direct trauma to the site

- During the postpartum period

- Congenital

About 25% of people over the age of 50 experience knee pain from degenerative knee diseases.

In the United States, more than US $3 billion is spent each year on arthroscopic knee surgeries that are known to be ineffective in people with degenerative knee pain.

The cause of trigger finger is unclear but several causes have been proposed. It has also been called stenosing tenosynovitis (specifically "digital tenosynovitis stenosans"), but this may be a misnomer, as inflammation is not a predominant feature.

It has been speculated that repetitive forceful use of a digit leads to narrowing of the fibrous digital sheath in which it runs, but there is little scientific data to support this theory. The relationship of trigger finger to work activities is debatable and scientific evidence for and against hand use as a cause exist. While the mechanism is unclear, there is some evidence that triggering of the thumb is more likely to occur following surgery for carpal tunnel syndrome. It may also occur in rheumatoid arthritis.

Tenosynovitis most commonly results from the introduction of bacteria into a sheath through a puncture or laceration wound, though bacteria can also be spread from adjacent tissue or via hematogenous spread. The clinical presentation is therefore as acute infection following trauma. The infection can be mono- or polymicrobial and can vary depending on the nature of the trauma. The most common pathogenic agent is staphylococcus aureus introduced from the skin. Other bacteria linked to infectious tenosynovitis include Pasteurella multocida (associated with animal bites), Eikenella spp. (associated with IV drug use), and Mycobacterium marinum (associated with wounds exposed to fresh or salt water). Additionally, sexually active patients are at risk for hematogenous spread due to Neisseria gonorrhea (see infectious arthritis).

Noninfectious tenosynovitis can arise from overuse or secondary to other systemic inflammatory conditions such as [rheumatoid arthritis] or [reactive arthritis]. If left untreated, the tendons may undergo stenosis, causing conditions such as de Quervain’s and trigger finger.

The natural history of disease for trigger finger remains uncertain.

There is some evidence that idiopathic trigger finger behaves differently in people with diabetes.

Recurrent triggering is unusual after successful injection and rare after successful surgery.

While difficulty extending the proximal interphalangeal joint may persist for months, it benefits from exercises to stretch the finger straighter.

Tenosynovitis is the inflammation of the fluid-filled sheath (called the synovium) that surrounds a tendon, typically leading to joint pain, swelling, and stiffness. Tenosynovitis can be either infectious or noninfectious. Common clinical manifestations of noninfectious tenosynovitis include de Quervain tendinopathy and stenosing tenosynovitis (more commonly known as trigger finger)

The cause of de Quervain's disease is not established. Evidence regarding a possible relation with occupational risk factors is debated. A systematic review of potential risk factors discussed in the literature did not find any evidence of a causal relationship with occupational factors. However, researchers in France found personal and work-related factors were associated with de Quervain's disease in the working population; wrist bending and movements associated with the twisting or driving of screws were the most significant of the work-related factors. Proponents of the view that De Quervain syndrome is a repetitive strain injury consider postures where the thumb is held in abduction and extension to be predisposing factors. Workers who perform rapid repetitive activities involving pinching, grasping, pulling or pushing have been considered at increased risk. Specific activities that have been postulated as potential risk factors include intensive computer mouse use, trackball use, and typing, as well as some pastimes, including bowling, golf, fly-fishing, piano-playing, sewing, and knitting.

Women are affected more often than men. The syndrome commonly occurs during and after pregnancy. Contributory factors may include hormonal changes, fluid retention and—more debatably—lifting.

Stenosing tenosynovitis (also known as trigger finger or trigger thumb) is a painful condition caused by the inflammation (tenosynovitis) and progressive restriction of the superficial and deep flexors fibrous tendon sheath adjacent to the A1 pulley at a metacarpal head. Repetitive forceful compression, tensile stress, and resistive flexion, causes inflammation, swelling, and microtrauma, that results in thickening (commonly a nodular formation) of the tendon distal to the pulley and stenosis of the tendon sheath leading to a painful digital base, limitation of finger movements, triggering, snapping, locking, and deformity progressively.

Patients report a popping sound at the proximal interphalangeal joint (PIP), morning stiffness with/without triggering, delayed and sometimes painful extension of the digit, and when more advanced, a locking position that requires manipulation to extend the affected finger. This condition more commonly affects the middle and ring fingers (occasionally the thumb), and the flexor rather than extensor tendons in the hand.

In rheumatic trigger finger (or in diabetes), more than one finger may be involved. Cases of stenosing peroneal tenosynovitis, have been reported where the patient presents with pain over the lateral malleolus, both with active and passive range of motion and no physical of radiographic evidence of instability.

Workers in certain fields are at risk of repetitive strains. Most occupational injuries are musculoskeletal disorders, and many of these are caused by cumulative trauma rather than a single event. Miners and poultry workers, for example, must make repeated motions which can cause tendon, muscular, and skeletal injuries.

Bicipital tenosynovitis is tendinitis or inflammation of the tendon and sheath lining of the biceps muscle. It is often the result of many years of small tears or other degenerative changes in the tendon first manifesting in middle age, but can be due to a sudden injury. Calcification of the tendon, and osteophytes ("bone spurs") in the intertubercular groove can be apparent on x-rays. The condition (which can also occur in dogs) is commonly treated with physical therapy and cortisone and/or surgery.

De Quervain syndrome, is a tenosynovitis of the sheath or tunnel that surrounds two tendons that control movement of the thumb.

Dupuytren’s disease has a high recurrence rate, especially when a person has so called Dupuytren’s diathesis. The term diathesis relates to certain features of Dupuytren's disease and indicates an aggressive course of disease.

The presence of all new Dupuytren’s diathesis factors increases the risk of recurrent Dupuytren’s disease by 71% compared with a baseline risk of 23% in people lacking the factors. In another study the prognostic value of diathesis was evaluated. They concluded that presence of diathesis can predict recurrence and extension. A scoring system was made to evaluate the risk of recurrence and extension evaluating the following values: bilateral hand involvement, little finger surgery, early onset of disease, plantar fibrosis, knuckle pads and radial side involvement.

Minimally invasive therapies may precede higher recurrence rates. Recurrence lacks a consensus definition. Furthermore, different standards and measurements follow from the various definitions.

Lameness is an abnormal gait or stance of an animal that is the result of dysfunction of the locomotor system. In the horse, it is most commonly caused by pain, but can be due to neurologic or mechanical dysfunction. Lameness is a common veterinary problem in racehorses, sport horses, and pleasure horses. It is one of the most costly health problems for the equine industry, both monetarily for the cost of diagnosis and treatment, and for the cost of time off resulting in loss-of-use.

Repetitive strain injury (RSI) and associative trauma orders are umbrella terms used to refer to several discrete conditions that can be associated with repetitive tasks, forceful exertions, vibrations, mechanical compression, or sustained/awkward positions. Examples of conditions that may sometimes be attributed to such causes include edema, tendinosis (or less often tendinitis), carpal tunnel syndrome, cubital tunnel syndrome, De Quervain syndrome, thoracic outlet syndrome, intersection syndrome, golfer's elbow (medial epicondylitis), tennis elbow (lateral epicondylitis), trigger finger (so-called stenosing tenosynovitis), radial tunnel syndrome, ulnar tunnel syndrome, and focal dystonia.

Since the 1970s there has been a worldwide increase in RSIs of the arms, hands, neck, and shoulder attributed to the widespread use of typewriters/computers in the workplace that require long periods of repetitive motions in a fixed posture.

Lameness is most commonly caused by pain, but may also be the result of neuromuscular disease or mechanical restriction. Lameness itself is a clinical sign, and not a diagnosis.

In one study, those with stage 2 of the disease were found to have a slightly increased risk of mortality, especially from cancer.

Having more than one risk factor greatly increases risk of septic arthritis.

One way to prevent this injury from occurring is to be informed and educated about the risks involved in hurting your wrist and hand. If patients do suffer from median nerve palsy, occupational therapy or wearing a splint can help reduce the pain and further damage. Wearing a dynamic splint, which pulls the thumb into opposition, will help prevent an excess in deformity. This splint can also assist in function and help the fingers flex towards the thumb. Stretching and the use of C-splints can also assist in prevention of further damage and deformity. These two methods can help in the degree of movement the thumb can have. While it is impossible to prevent trauma to your arms and wrist, patients can reduce the amount of compression by maintaining proper form during repetitive activities. Furthermore, strengthening and increasing flexibility reduces the risk of nerve compression.

Injuries to the arm, forearm or wrist area can lead to various nerve disorders. One such disorder is median nerve palsy. The median nerve controls the majority of the muscles in the forearm. It controls abduction of the thumb, flexion of hand at wrist, flexion of digital phalanx of the fingers, is the sensory nerve for the first three fingers, etc. Because of this major role of the median nerve, it is also called the eye of the hand. If the median nerve is damaged, the ability to abduct and oppose the thumb may be lost due to paralysis of the thenar muscles. Various other symptoms can occur which may be repaired through surgery and tendon transfers. Tendon transfers have been very successful in restoring motor function and improving functional outcomes in patients with median nerve palsy.

Most cases of septic arthritis involve only one organism; however, polymicrobial infections can occur, especially after large open injuries to the joint.

- Staphyloccoci

- Staphylococcus aureus - the most common cause in most age groups. Can be caused by skin infection, previously damaged joint, prosthetic joint, or intravenous drug use.

- coagulase-negative staphylococci - usually due to prosthetic joint

- Streptococci - the second most common cause

- Streptococcus pyogenes - a common cause in children under 5

- Streptococcus pneumoniae

- Group B streptococci - a common cause in infants

- Haemophilus influenzae

- Neisseria gonorrhoeae - the most common cause of septic arthritis in young, sexually active adults. Multiple macules or vesicles seen over the trunk are a pathognomonic feature.

- Neisseria meningitidis

- Escherichia coli - in the elderly, IV drug users and the seriously ill

- Pseudomonas aeruginosa - IV drug users or penetrating trauma through the shoe

- M. tuberculosis, Salmonella spp. and Brucella spp. - cause septic spinal arthritis

- Eikenella corrodens - human bites

- Pasteurella multocida, bartonella henselae - animal bites or scratches

- Fungal species - immunocompromised state

- Borrelia burgodorferi - ticks, causes lyme disease

Individuals affected by RS3PE typically have repeated episodes of inflammation of the lining of their synovial joints and swelling of the end portion of the limbs. The arms and hands are more commonly affected than the legs and feet. Both sides are usually involved though RS3PE can affect only one side in certain cases.

Remitting seronegative symmetrical synovitis with pitting edema (abbreviated RS3PE or sometimes RSPE) is a rare syndrome identified by symmetric polyarthritis, synovitis, acute pitting edema (swelling) of the back of the hands and/or feet, and a negative serum rheumatoid factor. If no underlying disorder can be identified (idiopathic RS3PE), this entity has an excellent prognosis and responds well to treatment.

RS3PE typically involves the joints of the extremities, specifically the metacarpophalangeal and proximal interphalangeal joints, wrists, shoulders, elbows, knees and ankles.

It is more common in older adults, with the mean age between 70 and 80 years in most studies.

It occurs more often in men than in women with a 2:1 ratio.

It is unknown how common this condition is.

The cause of JIA remains a mystery. However, the disorder is autoimmune — meaning that the body's own immune system starts to attack and destroy cells and tissues (particularly in the joints) for no apparent reason. The immune system is thought to be provoked by changes in the environment, in combination with mutations in many associated genes and/or other causes of differential expression of genes. Experimental studies have shown that certain mutated viruses may be able to trigger JIA. The disease appears to be more common in girls, and the disease is most common in Caucasians.

Associated factors that may worsen or have been linked to rheumatoid arthritis include:

- Genetic predisposition; When one family member has been diagnosed with rheumatoid arthritis or another autoimmune disorder, the chances are higher that other family members or siblings may also develop arthritis.

- Females are more likely to develop rheumatoid arthritis than males at all ages.

- A strong belief is held that psychological stress may worsen the symptoms of rheumatoid arthritis. However, when the emotional stress is under control, the arthritis symptoms do not always disappear, suggesting that the association is not straightforward.

- Though no distinct immune factor has been isolated as a cause of arthritis, some experts believe that the triggering factor may be something like a virus which then disappears from the body after permanent damage is done.

- Because rheumatoid arthritis is more common in women, perhaps sex hormones may play a role in causing or modulating arthritis. Unfortunately, neither sex hormone deficiency nor replacement has been shown to improve or worsen arthritis.

The cause of JIA, as the word "idiopathic" suggests, is unknown and an area of active research. Current understanding of JIA suggests that it arises in a genetically susceptible individual due to environmental factors.

Giant-cell tumor of the tendon sheath, also known as giant-cell synovioma and localized nodular tenosynovitis, is a firm lesion, measuring 1 to 3 cm in diameter, and is most commonly attached to the tendons of the fingers, hands, and wrists, with a predilection for the flexor surfaces. Giant-cell tumor of tendon sheaths most often affect the wrist and fingers of males and females from the ages of 20-50 . These tumors are typically painless and can cause cortical erosion. Surgery to remove the tumor is a common treatment, though the tumors tend to recur.