DISH can present with spinal stiffness on forward flexion/back extension, or with mild back pain. It is symptomatic for thoracic spinal pain in approximately 80% of patients. Back pain or stiffness is worse in the morning in almost two-thirds of patients. It may also be asymptomatic and discovered as an incidental radiological abnormality. Dysphagia from cervical spine osteophyte impingement of esophagus is reported in some cases. Similar calcification and ossification may be seen at peripheral entheseal sites, including the shoulder, iliac crest, ischial tuberosity, trochanters of the hip, tibial tuberosities, patellae, and bones of the hands and/or feet.

Diffuse idiopathic skeletal hyperostosis (DISH) is a non-inflammatory spondyloarthropathy which predominantly affects the spine. It is characterized by ankylosis and enthesopathy (ossification of the ligaments and entheses). It most commonly affects the thoracic and thoraco-lumbar spine, but involvement is variable and can include the entire spine.

Patients usually complain of pain in one joint, which persists for months, or even years, does not ease with exercise, steroid injection or heat treatment, shows nothing on X-ray, but shows a definite restriction of movement.

There are 3 defined stages to this disease:

- early: no loose bodies but active synovial disease;

- transitional: active synovial disease, and loose bodies;

- late: loose bodies but no synovial disease;

In the early stages of the disease it is often confused with tendinitis and/or arthritis. Once it reaches transitional the loose bodies become apparent with X-ray in greater than 70% of cases, with MRI often showing where xray fails. In experienced hands, US is also useful for the diagnosis.

In the disease, the thin flexible membrane of the synovium gradually forms blisters which calcify and enlarge. These nodules eventually break free and float around the joint space becoming larger – these add to the discomfort and stiffness of the joint.

The disease is rare and little known and there is currently no known cure. The affected tissue will show up as a semi-solid mass in a MRI scan, final diagnosis is usually confirmed by taking a biopsy.

Synovial chondromatosis occurs twice as commonly in males as females and usually in their forties. However, online communities for synovial chondromatosis patients have yielded a stark contrast, with equal representation from both genders and members diagnosed as young as late teenage/early 20s.

The disease generally affects only one of the larger weight bearing joints (hip, ankle, knee) – although the elbow, and wrist can also be affected. Rarely involves the temporal mandibular joint.

Hypermobility generally results from one or more of the following:

- Abnormally shaped ends of one or more bones at a joint

- A Type 1 collagen or other connective tissue defect (as found in Ehlers-Danlos syndrome, Loeys-Dietz syndrome and Marfan syndrome) resulting in weakened ligaments/ligamentous laxity, muscles and tendons. This same defect also results in weakened bones, which may result in osteoporosis and fractures.

- Abnormal joint proprioception (an impaired ability to locate body parts in space and/or monitor an extended joint)

These abnormalities cause abnormal joint stress, meaning that the joints can wear out, leading to osteoarthritis.

The condition tends to run in families, suggesting a genetic basis for at least some forms of hypermobility. The term "double jointed" is often used to describe hypermobility; however, the name is a misnomer and should not be taken literally, as hypermobile joints are not doubled/extra in any sense.

Most people have hypermobility with no other symptoms. Approximately 5% of the healthy population have one or more hypermobile joints. However, people with "joint hypermobility syndrome" are subject to many difficulties. For example, their joints may be easily injured, be more prone to complete dislocation due to the weakly stabilized joint and they may develop problems from muscle fatigue (as muscles must work harder to compensate for weakness in the ligaments that support the joints). Hypermobility syndrome can lead to chronic pain or even disability in severe cases. Musical instrumentalists with hypermobile fingers may have difficulties when fingers collapse into the finger locking position. Or, conversely, they may display superior abilities due to their increased range of motion for fingering, such as in playing a violin or cello.

Hypermobility may be symptomatic of a serious medical condition, such as Stickler Syndrome, Ehlers-Danlos syndrome, Marfan syndrome, Loeys-Dietz syndrome, rheumatoid arthritis, osteogenesis imperfecta, lupus, polio, Down syndrome, morquio syndrome, cleidocranial dysostosis or myotonia congenita.

Hypermobility has been associated with chronic fatigue syndrome and fibromyalgia. Hypermobility causes physical trauma (in the form of joint dislocations, joint subluxations, joint instability, sprains, etc.). These conditions often, in turn, cause physical and/or emotional trauma and are possible triggers for conditions such as fibromyalgia.

Women with hypermobility may experience particular difficulties when pregnant. During pregnancy, the body releases certain hormones that alter ligament physiology, easing the stretching needed to accommodate fetal growth as well as the birthing process. The combination of hypermobility and pregnancy-related pelvic girdle during pregnancy can be debilitating. The pregnant woman with hypermobile joints will often be in significant pain as muscles and joints adapt to the pregnancy. Pain often inhibits such women from standing or walking during pregnancy. The pregnant patient may be forced to use a bedpan and/or a wheelchair during pregnancy and may experience permanent disability.

Symptoms of hypermobility include a dull but intense pain around the knee and ankle joints and the soles of the feet. The pain and discomfort affecting these body parts can be alleviated by using custom orthoses.

Synovial chondromatosis (synonyms include synovial osteochondromatosis, primary synovial osteochondromatosis, and synovial chondrometaplasia) is a disease affecting the synovium, a thin flexible membrane around a joint. It is also known as Reichel's syndrome or Reichel-Jones-Henderson syndrome, named after Friedrich Paul Reichel, Hugh Toland Jones and Melvin Starkey Henderson.

People with Joint Hypermobility Syndrome may develop other conditions caused by their unstable joints. These conditions include:

- Joint instability causing frequent sprains, tendinitis, or bursitis when doing activities that would not affect others

- Joint pain

- Early-onset osteoarthritis (as early as during teen years)

- Subluxations or dislocations, especially in the shoulder (severe limits to ability to push, pull, grasp, finger, reach, etc., is considered a disability by the US Social Security Administration)

- Knee pain

- Fatigue, even after short periods of exercise

- Back pain, prolapsed discs or spondylolisthesis

- Joints that make clicking noises (also a symptom of osteoarthritis)

- Susceptibility to whiplash

- Temporomandibular Joint Syndrome also known as TMJ

- Increased nerve compression disorders (such as carpal tunnel syndrome)

- The ability of finger locking

- Poor response to anaesthetic or pain medication

- "Growing pains" as described in children in late afternoon or night

Scoliosis, is a medical condition where a person's spine has several irregular curves that are located between the neck and the pelvis. Symptoms of scoliosis in mild cases usually exhibit abnormal posture, back pain, tingling or numbness in the legs and in worse cases can exhibit breathing problems, fatigue, permanent deformities and in rare cases heart problems.

In traumatic heterotopic ossification (traumatic myositis ossificans), the patient may complain of a warm, tender, firm swelling in a muscle and decreased range of motion in the joint served by the muscle involved. There is often a history of a blow or other trauma to the area a few weeks to a few months earlier. Patients with traumatic neurological injuries, severe neurologic disorders or severe burns who develop heterotopic ossification experience limitation of motion in the areas affected.

Lazy eye, in particular strabismus may be the result of coordination between the extraocular muscles, which prevents a person on directing both eyes in unison towards the same fixation point. The main cause of strabismus is usually the muscular imbalance of the six surrounding muscles that allow both eyes to focus on the same object. As each eye does not have the same focus, different images are sent to the brain, confusing it, resulting in the brain ignoring the image from the weaker eye and if left untreated will cause a loss of vision in the ignored eye called amblyopia. Further symptoms of strabismus include decreased vision, double vision, headaches, asthenopia and eye fatigue.

An individual with Panner disease most commonly experiences elbow pain near the capitellum. Other symptoms include:

- Stiffness in the elbow

- Elbow swelling

- Limited range of motion

- Elbow extension limitation

- Tenderness

These symptoms worsen with physical activity such a throwing a ball or gymnastics for example. The symptoms begin unexpectedly and are often present for several days or weeks, and the symptoms tend to last even longer.

In general, pigmented villonodular synovitis often manifests initially as sudden onset, unexplained joint swelling and pain; the joint swelling is disproportionate to the amount of pain the patient feels at first. Decreased motion and increased pain occur as the disorder progresses as well as locking of the joint. The localized form often manifests initially as a painless, slow-growing mass and progresses to the other common symptoms of PVNS. The swelling often feels warm to the touch. Diffuse PVNS symptoms are often confused with those of Rheumatoid arthritis. While pigmented villonodular synovitis can occur in both pediatric and geriatric patients, it is more common with ages 20–50.

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Tendinopathy refers to a disease of a tendon. The clinical presentation includes tenderness on palpation and pain, often when exercising or with movement.

Three terms have evolved in the medical terminology to refer to injuries that cause tendon pain:

- Tendinitis - acute tendon injury accompanied by inflammation

- Tendinosis - chronic tendon injury with degeneration at the cellular level and no inflammation

- Paratenonitis - Inflammation of the outer layer of the tendon (paratenon) alone, whether or not the paratenon is lined by synovium

- Paratenonitis with tendinosis - Paratenonitis associated with intratendinous degeneration

- Tendinopathy - chronic tendon injury with no implication about etiology

Tendon injuries arise from a combination of intrinsic and extrinsic factors; acute tendon injuries may be predominantly caused by extrinsic factors, whereas in overuse syndromes as in the case of tendinopathy it may be caused by multifactorial combinations of both intrinsic and extrinsic factors. An example of an intrinsic factor for tendinopathies are: poor biomechanics such as limb malalignments and hyperpronation that may cause increased traction loads acting on the foot and ankle that may increase the incidence of Achilles, flexor hallucis longus muscle, and tibialis posterior muscle tendinopathies.

Genu valgum, commonly called "knock-knee", is a condition in which the knees angle in and touch each other when the legs are straightened. Individuals with severe valgus deformities are typically unable to touch their feet together while simultaneously straightening the legs. The term originates from the Latin "genu", "knee", and "valgus" which actually means bent outwards, but in this case, it is used to describe the distal portion of the knee joint which bends outwards and thus the proximal portion seems to be bent inwards. For citation and more information on uses of the words Valgus and Varus, please visit the internal link to -varus.

Mild genu valgum is diagnosed when a person standing upright with the feet touching also shows the knees touching. It can be seen in children from ages 2 to 5, and is often corrected naturally as children grow. However, the condition may continue or worsen with age, particularly when it is the result of a disease, such as rickets or obesity. Idiopathic genu valgum is a form that is either congenital or has no known cause.

Other systemic conditions may be associated, such as Schnyder crystalline corneal dystrophy, an autosomal dominant condition frequently reported with hyperlipidemia.

The degree of genu valgum can be estimated by the , which is the angle formed by a line drawn from the anterior superior iliac spine through the center of the patella and a line drawn from the center of the patella to the center of the tibial tubercle. In women, the Q angle should be less than 22 degrees with the knee in extension and less than 9 degrees with the knee in 90 degrees of flexion. In men, the Q angle should be less than 18 degrees with the knee in extension and less than 8 degrees with the knee in 90 degrees of flexion. A typical Q angle is 12 degrees for men and 17 degrees for women.

Elbow dysplasia is a condition involving multiple developmental abnormalities of the elbow-joint in the dog, specifically the growth of cartilage or the structures surrounding it. These abnormalities, known as 'primary lesions', give rise to osteoarthritic processes. Elbow dysplasia is a common condition of certain breeds of dogs.

Most primary lesions are related to osteochondrosis, which is a disease of the joint cartilage and specifically Osteochondritis dissecans (OCD or OD), the separation of a flap of cartilage on the joint surface. Other common causes of elbow dysplasia included ununited anconeal process (UAP) and fragmented or ununited medial coronoid process (FCP or FMCP).

Osteochondritis dissecans is difficult to diagnose clinically as the animal may only exhibit an unusual gait. Consequently, OCD may be masked by, or misdiagnosed as, other skeletal and joint conditions such as hip dysplasia. The problem develops in puppyhood although often subclinically, and there may be pain or stiffness, discomfort on extension, or other compensating characteristics. Diagnosis generally depends on X-rays, arthroscopy, or MRI scans. While cases of OCD of the stifle go undetected and heal spontaneously, others are exhibited in acute lameness. Surgery is recommended once the animal has been deemed lame, before then non-surgical control is usually used.

Repeated, periodic joint effusions of the knee. Usually one knee is affected but sometimes both knees. Other joints may also be involved along with the knee. Effusions are large, restricting range of motion but significant pain is not a feature. There is usually stiffness. Tenderness of the joint may or may not be present. Aspirated synovial fluid is usually sterile but will sometimes show elevated cell count (>100 cells/mL) with 50% being polymorphonuclear leukocytes.

Onset of effusions are sudden with no particular trigger or stimulus. Each episode lasts for a few days to about a week and recurs in cycles of 7 to 11 days with extremes of 3 days to 30 days also reported. Sometimes the joint may begin to swell again as soon as the fluid has subsided. Where both knees are affected concurrently, as one joint ceases to swell the other may become involved.

The cycle of joints swellings have been reported as being very regular, even predictable. This has been a characteristic feature of IH in many case reports. However, over the longer-term especially, these cycles of effusion and recovery may not be as constant as first reported.

In women, many cases seem to begin at puberty. Episodes of knee swelling may coincide the menstrual cycle. In nearly all case reports, pregnancy seems to suppress the condition but after birth, during lactation, it returns.

In the main, patients are mostly free of other symptoms. Fever is rare. There no signs of local inflammation or lymphatic involvement. Laboratory tests are generally normal or within reference limits.

PVNS is locally aggressive and can spread to surrounding tissues, causing bone erosion and tissue damage. If not treated early, it can spread to areas outside the joint, and potentially cause permanent loss of range as well as intense pain. The disorder also has, on average, a 45% rate of recurrence.

As the grinding components cause metal flakes to shed from the system, the implant wears down. Metallosis results in numerous additional side effects:

- Confusion;

- Feelings of malaise;

- Gastrointestinal problems;

- Emotional disturbance;

- Recurring infections;

- Dizziness;

- Headaches;

- Problems in the nervous system (feelings of burning, tingling, or numbness of the extremities); and

- Cobalt poisoning (skin rashes, cardiomyopathy, problems with hearing, sight or cognition, tremors, and hypothyroidism).

Panner disease is an osteochondrosis of the capitellum of the elbow. Panner disease is primarily seen in boys between the ages of five and ten years old. Panner disease is often caused by excessive throwing due to valgus stress. The disease causes pain and stiffness in the affected elbow and may limit extension; the affected elbow is usually on the dominant arm the child uses. The disease may be associated with pitching and athletic activity. On radiographs, the capitellum may appear irregular with areas of radiolucency. Treatment is symptomatic, with a good prognosis. Treatment is minimal and includes restricting athletic activity to allow for the elbow to heal and for pain to be relieved. The disease is named after the Danish radiologist Hans Jessen Panner (1871–1930).

Persons suffering from metallosis can experience any of the following symptoms:

- Extreme pain (even when not moving);

- Swelling and inflammation;

- Loosening of the implant;

- Dislocation;

- Bone deterioration;

- Aseptic fibrosis, local necrosis;

- Hip replacement failure;

- Metal toxicity from grinding metal components; and

- Necessary subsequent hip replacement revision or surgeries.

Fibrous ankylosis is a fibrous connective tissue process which results in decreased range of motion. Symptoms present as bony ankylosis, in which osseous tissue fuses two bones together reducing mobility, which is why fibrous ankylosis is also known as false ankylosis.

Pathology may be the result of trauma, disease, chronic inflammation, or surgery.

Some research suggests fibrous ankylosis may precede the development of bony ankylosis

Heterotopic ossification (HO) is the process by which bone tissue forms outside of the skeleton.

The condition is usually characterized by a sudden onset of knee pain, worse at night. Examination reveals tenderness of the medial femoral condyle, joint effusion, and occasional locking of the knee joint.

Elbow Dysplasia is a significant genetically determined problem in many breeds of dog, often manifesting from puppyhood and continuing for life. In elbow dysplasia, the complex elbow joint suffers from a structural defect, often related to its cartilage. This initial condition, known as a "primary lesion", causes an abnormal level of wear and tear and gradual degradation of the joint, at times disabling or with chronic pain. Secondary processes such as inflammation and osteoarthritis can arise from this damage which increase the problem and add further problems of their own.

Intermittent hydrarthrosis (IH), also known as "periodic synoviosis", "periodic benign synovitis", or "periodic hydrarthritis", is a chronic condition of unknown cause characterized by recurring, temporary episodes of fluid accumulation in the knee. While the knee is mainly involved, occasionally other joints such as the elbow or ankle can additionally be affected. Fluid accumulation in the joint can be extensive causing discomfort and impairing movement, although affected joints are not usually very painful. While the condition is chronic, it does not appear to progress to more destructive damage of the joint. It seems to affect slightly more women than men.

Episodes of swelling last several days or longer, can occur with regular or semi-regular frequency, typically one or two episodes per month. Between periods of effusion, knee swelling reduces dramatically providing largely symptomless intervals. Unlike some other rheumatological conditions such as rheumatoid arthritis, laboratory findings are usually within normal ranges or limits.

Clear treatment options have yet to be established. NSAIDs and COX2-inhibitors are generally not effective. Where this condition has been correctly diagnosed, various anti-rheumatic drugs as well as colchicine may be trialled to find the most effective option. More aggressive intra-articular treatment such chemical or radio-active synovectomy can also be helpful although benefits beyond 1 year have not been reported in literature.