The most common manifestation of infectious tenosynovitis is in the flexor tendons of the fingers, though infections of other tendon sheaths have been reported as well. The four cardinal signs of infectious flexor tenosynovitis are tenderness to touch along the flexor aspect of the finger, symmetric enlargement of the affected finger, the finger being held in slight flexion at rest, and severe pain with passive extension. Fever may also be present but is uncommon.

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)

Stenosing tenosynovitis often presents with a painful and swollen thumb with limited range of motion, or a ring finger or middle finger with similarly limited motion. There is often a feeling of catching when the thumb is flexed. In the ring and middle fingers, often a nodule can be felt when you press the area of the hand where the palm meets the finger.

Patients with trochleitis typically experience a dull fluctuating aching over the trochlear region developing over a few days. Some may also feel occasional sharp pains punctuating the ache. In patients with migraines, trochleitis may occur simultaneously with headache. Presentation is usually unilateral with palpable swelling over the affected area supranasal to the eye. The trochlear region is extremely tender to touch. Pain is exacerbated by eye movements looking down and inwards, and especially in supraduction (looking up) and looking outwards, which stretches the superior oblique muscle tendon. Notably, there is no restriction of extraocular movements, no diplopia, and often no apparent ocular signs such as proptosis. However, occasionally mild ptosis is found. The absence of generalized signs of orbital involvement is helpful in eliminating other more common causes of periorbital pain.

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.

The typical signs and symptoms of cellulitis is an area which is red, hot, and painful. The photos shown here of are of mild to moderate cases, and are not representative of earlier stages of the condition.

Bursitis commonly affects superficial bursae. These include the subacromial, prepatellar, retrocalcaneal, and pes anserinus bursae of the shoulder, knee, heel and shin, etc. (see below). Symptoms vary from localized warmth and erythema to joint pain and stiffness, to stinging pain that surrounds the joint around the inflamed bursa. In this condition, the pain usually is worse during and after activity, and then the bursa and the surrounding joint becomes stiff the next morning.

Bursitis is the inflammation of one or more bursae (small sacs) of synovial fluid in the body. They are lined with a synovial membrane that secretes a lubricating synovial fluid. There are more than 150 bursae in the human body. The bursae rest at the points where internal functionaries, such as muscles and tendons, slide across bone. Healthy bursae create a smooth, almost frictionless functional gliding surface making normal movement painless. When bursitis occurs, however, movement relying on the inflamed bursa becomes difficult and painful. Moreover, movement of tendons and muscles over the inflamed bursa aggravates its inflammation, perpetuating the problem. Muscle can also be stiffened.

Cellulitis is caused by a type of bacteria entering the skin, usually by way of a cut, abrasion, or break in the skin. This break does not need to be visible. Group A "Streptococcus" and "Staphylococcus" are the most common of these bacteria, which are part of the normal flora of the skin, but normally cause no actual infection while on the skin's outer surface.

About 80% of cases of Ludwig's angina, or cellulitis of the submandibular space, are caused by dental infections. Mixed infections, due to both aerobes and anaerobes, are commonly associated with this type of cellulitis. Typically, this includes alpha-hemolytic streptococci, staphylococci, and bacteroides groups.

Predisposing conditions for cellulitis include insect or spider bite, blistering, animal bite, tattoos, pruritic (itchy) skin rash, recent surgery, athlete's foot, dry skin, eczema, injecting drugs (especially subcutaneous or intramuscular injection or where an attempted intravenous injection "misses" or blows the vein), pregnancy, diabetes, and obesity, which can affect circulation, as well as burns and boils, though debate exists as to whether minor foot lesions contribute. Occurrences of cellulitis may also be associated with the rare condition hidradenitis suppurativa or dissecting cellulitis.

The appearance of the skin assists a doctor in determining a diagnosis. A doctor may also suggest blood tests, a wound culture, or other tests to help rule out a blood clot deep in the veins of the legs. Cellulitis in the lower leg is characterized by signs and symptoms similar to those of a deep vein thrombosis, such as warmth, pain, and swelling (inflammation).

This reddened skin or rash may signal a deeper, more serious infection of the inner layers of skin. Once below the skin, the bacteria can spread rapidly, entering the lymph nodes and the bloodstream and spreading throughout the body. This can result in influenza-like symptoms with a high temperature and sweating or feeling very cold with shaking, as the sufferer cannot get warm.

In rare cases, the infection can spread to the deep layer of tissue called the fascial lining. Necrotizing fasciitis, also called by the media "flesh-eating bacteria", is an example of a deep-layer infection. It is a medical emergency.

Trochleitis is inflammation of the superior oblique tendon trochlea apparatus characterized by localized swelling, tenderness, and severe pain. This condition is an uncommon but treatable cause of periorbital pain. The trochlea is a ring-like apparatus of cartilage through which passes the tendon of the superior oblique muscle. It is located in the superior nasal orbit and functions as a pulley for the superior oblique muscle. Inflammation of the trochlear region leads to a painful syndrome with swelling and exquisite point tenderness in the upper medial rim of the orbit. A vicious cycle may ensue such that inflammation causes swelling and fraying of the tendon which then increases the friction of passing through the trochlea which in turn adds to the inflammation. Trochleitis has also been associated with triggering or worsening of migraine attacks in patients with pre-existing migraines (Yanguela, 2002).

Retrocalcaneal bursitis is an inflammation of the bursa located between the calcaneus and the anterior surface of the Achilles tendon. It commonly occurs in association with rheumatoid arthritis, spondyloarthropathies, gout, and trauma.

The pain is usually on the back of the heel and swelling appears on lateral or medial side of the tendon.

Trigger fingers is a common disorder characterized by catching, snapping or locking of the involved finger flexor tendon, associated with dysfunction and pain. It is a sub-set of stenosing tenosynovitis.

A disparity in size between the flexor tendon and the surrounding retinacular pulley system, most commonly at the level of the first annular (A1) pulley, results in difficulty flexing or extending the finger and the "triggering" phenomenon. The label of trigger finger is used because when the finger unlocks, it pops back suddenly, as if releasing a trigger on a gun.

Enthesitis is inflammation of the entheses, the sites where tendons or ligaments insert into the bone. It is also called enthesopathy, or any pathologic condition involving the entheses. The entheses are any point of attachment of skeletal muscles to the bone, where recurring stress or inflammatory autoimmune disease can cause inflammation or occasionally fibrosis and calcification. One of the primary entheses involved in inflammatory autoimmune disease is at the heel, particularly the Achilles tendon.

It is associated with HLA B27 arthropathies like ankylosing spondylitis, psoriatic arthritis, and reactive arthritis. Symptoms include multiple points of tenderness at the heel, tibial tuberosity, iliac crest, and other tendon insertion sites.

Symptoms can vary from aches or pains and local joint stiffness, to a burning that surrounds the whole joint around the inflamed tendon. In some cases, swelling occurs along with heat and redness, and there may be visible knots surrounding the joint. With this condition, the pain is usually worse during and after activity, and the tendon and joint area can become stiff the following day as muscles tighten from the movement of the tendon. Many patients report stressful situations in their life in correlation with the beginnings of pain which may contribute to the symptoms.

If the symptoms of tendinitis last for several months (6 months) or longer, it is probably tendinosis.

Achilles bursitis is bursitis (inflammation of synovial sac) of bursa situated above the insertion of tendon to calcaneus. It results from overuse and wearing of tight shoes.

Tendinitis (also tendonitis), meaning inflammation of a tendon, is a type of tendinopathy often confused with the more common tendinosis, which has similar symptoms but requires different treatment. (The suffix "-itis" denotes diseases characterized by inflammation.) The term tendinitis is generally reserved for tendon injuries that involve larger-scale acute injuries accompanied by inflammation. Tendinitis is typically referred to in combination with the body part involved, such as Achilles tendinitis (affecting the Achilles tendon), or patellar tendinitis (jumper's knee, affecting the patellar tendon).

Diagnosis is made almost exclusively by history and physical examination alone. More than one finger may be affected at a time, though it usually affects the index, thumb, middle, or ring finger. The triggering is usually more pronounced late at night and into the morning, or while gripping an object firmly.

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.

Jaccoud arthropathy (JA), Jaccoud deformity or Jaccoud's arthopathy is a chronic non-erosive reversible joint disorder that may occur after repeated bouts of arthritis. It is caused by inflammation of the joint capsule and subsequent fibrotic retraction, causing ulnar deviation of the fingers, through metacarpophalangeal joint (MCP) subluxation, primarily of the ring and little-finger. Joints in the feet, knees and shoulders may also get affected. It is commonly associated with systemic lupus erythematosus (SLE), and occurs in roughly 5% of all cases.

When associated with rheumatic fever it is also called chronic post–RF arthropathy.

Originally thought to be associated only with rheumatic fever, it has since been shown to occur also in SLE, Sjögren syndrome, scleroderma, dermatomyositis, psoriatic arthritis, vasculitis, ankylosing spondylitis, mixed connective tissue disease, and pyrophosphate deposition disease. It is distinct from bone erosion which is commonly associated with rheumatic arthritis, and also distinct from mild deforming arthropathy which is associated with SLE. There have also been cases of non-rheumatic JA associated with Lyme disease, HIV-infection and a number of other conditions.

Treatment focuses toward alleviating pain and in maintaining functionality of the affected joints through use of nonsteroidal anti-inflammatory drugs, corticosteroids, antimalarial drugs and physiotherapy. Surgery is also a possibility, with osteotomy or stabilization with Kirschner intramedullary wire. Tendon relocation, however, has been shown to only work in 30% of cases. The condition is named after the French 19th century physician Sigismond Jaccoud.

Tendinosis, sometimes called chronic tendinitis, chronic tendinopathy, or chronic tendon injury, is damage to a tendon at a cellular level (the suffix "osis" implies a pathology of chronic degeneration without inflammation). It is thought to be caused by microtears in the connective tissue in and around the tendon, leading to an increase in tendon repair cells. This may lead to reduced tensile strength, thus increasing the chance of tendon rupture. Tendinosis is often misdiagnosed as tendinitis because of the limited understanding of tendinopathies by the medical community. Classic characteristics of "tendinosis" include degenerative changes in the collagenous matrix, hypercellularity, hypervascularity, and a lack of inflammatory cells which has challenged the original misnomer "tendinitis".

Symptoms are pain at the radial side of the wrist, spasms, tenderness, occasional burning sensation in the hand, and swelling over the thumb side of the wrist, and difficulty gripping with the affected side of the hand. The onset is often gradual. Pain is made worse by movement of the thumb and wrist, and may radiate to the thumb or the forearm.

Infrapatellar bursitis is the inflammation of one or both of the infrapatellar bursa, which are located just below the kneecap. Symptoms of bursitis commonly include swelling and knee pain. Bursitis often develops gradually over a period of days to even months but may develop more rapidly, especially in the event of trauma or infection.

Bursitis affecting the superficial infrapatellar bursa is an occupational hazard of persons whose work involves kneeling on hard surfaces. Depending on the occupation affected it is known by a variety of nicknames, most commonly floor layers' knee, but also plumbers' knee, clergyman's knee, or housewife's knee (prepatellar bursitis).

The deep infrapatellar bursa occasionally also become inflamed, swollen, and painful. Bursitis in the deep infrapatellar bursa usually develops from chronic overuse of the knee extensor tendon (patellar tendon) as can occur with repetitive flexing of the knee under pressure in work duties or exercise. Examples might include climbing stairs, jumping, or deep knee bends.

Pain is often aggravated by elevation of the arm above shoulder level or by lying on the shoulder. Pain may awaken the patient from sleep. Other complaints may be stiffness, snapping, catching, or weakness of the shoulder.

Symptoms can vary from an ache or pain and stiffness to the local area of the tendon, or a burning that surrounds the whole joint around the affected tendon. With this condition, the pain is usually worse during and after activity, and the tendon and joint area can become stiffer the following day as swelling impinges on the movement of the tendon. Many patients report stressful situations in their life in correlation with the beginnings of pain, which may contribute to the symptoms.

Swelling in a region of micro damage or partial tear may be detected visually or by touch.

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.