What is tenosynovitis?

Tenosynovitis is a broad term describing an inflammatory condition which affects the tendon sheath within synovial joints, which can be of an infectious or non-infectious aetiology.¹ It typically presents with pain, swelling, and tenderness of the involved tendons.

What are the conditions of gout and pseudogout?

Both Gout and ‘Pseudogout’ are inflammatory types of arthritis caused by crystal deposits that build up in the joint. Gout is caused by crystals, otherwise referred to as monosodium urate crystals, and Pseudogout, formally known as calcium pyrophosphate dihydrate deposition disease (CPPD).

What is the relationship between tenosynovitis and gout/pseudogout

While all distinct clinical conditions which predominantly involve joint inflammation, Gout/ Pseudogout and Tenosynovitis differ mainly in their pathophysiology or presentation. The relationship between the conditions occurs when crystals ( Gout/ Pseudogout) deposit in the tendon sheaths within the joints and surrounding tissues, and an inflammatory response triggers.²

Understanding tenosynovitis

What happens in tenosynovitis?

Tendons are tough cords of tissue that connect muscles to bones. When you contract (tighten) a group of muscles, tendons pull on the attached bones, moving them, thus allowing you to make a wide range of movements.³ Tendons essentially work as levers, working in tandem with the contraction/expansion of muscles. The synovial membrane is a layer of connective tissue that produces synovial fluid and lines the cavities of joints and tendon sheaths. It acts as a lubricant, providing a low-friction environment and protecting the tendons.⁴

Tenosynovitis represents a common clinical condition characterised by inflammation of the synovium that surrounds the tendon sheath.⁵ In other words, Tenosynovitis occurs when the fluid surrounding the tendons in a joint becomes irritated, reddened, swollen and/or hot. The condition can affect any tendon in the body, but most commonly occurs in joints of the hand, wrist and feet.¹ Tenosynovitis can have either infective or non-infective causes, including autoimmune, overuse or can also occur spontaneously.¹

What are the most common symptoms of tenosynovitis?

• Pain
• Swelling
• Tenderness
• Limited movement
• Discolouration

What risk factors are associated with tenosynovitis?

Tenosynovitis can affect anyone; however, there are numerous risk factors which can add to the likelihood of developing the condition. These include:

• Rheumatoid arthritis
• Gout
• Diabetes⁷
• Thyroid disease
• Infections of the joints⁶
• A history of injury
• Chronic misuse/overuse
• Age

What is the relationship between Gout and Tenosynovitis?

What is gout?

Gout is an inflammatory arthritis resulting from the deposit of monosodium urate (MSU) crystals in joints, typically due to prolonged abnormally high levels of uric acid in the blood known as hyperuricaemia.² It often presents acutely with intermittent flares of joint pain.

Uric acid is a byproduct of our metabolism and DNA building blocks. When this is overproduced and underexcreted by the kidneys, we encounter a surplus of these needle-shaped MSU crystals deposited in the blood and synovial fluid.²

What is the mechanism of tenosynovitis in gout?

Gout symptoms are triggered by the inflammatory response to MSU. The first response of the body’s immune system to a harmful foreign substance is to release immune cells, which attempt to destroy the foreign bodies. In the case of Gout, MSU deposits in joints, irritating the surrounding tissue, which leads to the immune response cascade, causing tenosynovitis.^9,10

What is the clinical presentation of gout-related tenosynovitis?

Although an uncommon manifestation, the clinical features of Gout-related tenosynovitis can be mistaken for infectious tenosynovitis, often leading to misdiagnosis. The most common clinical appearance of patients:

• Swelling and tenderness¹¹
• Joint involvement most commonly involves/is seen in fingers, wrist, elbow, and toes
• Recurrent Episodes of pain in the joint

How is gout diagnosed?

Diagnosis begins with a detailed medical history, allowing the clinical team to differentiate between an infectious or chronic cause of the condition.

• A physical exam allows clinicians to visualise the range of motion and any redness or swelling.
• A laboratory analysis follows, including Synovial fluid analysis for crystal microscopy and serum urate levels.
• Imaging, including X-ray and ultrasound, can be performed, but not always necessary¹

How can I manage gout-related tenosynovitis?

Early recognition and management are crucial in the prevention of irreversible tendon damage. Treatment strategies include medications not limited to: nonsteroidal anti-inflammatory drugs (NSAIDs), colchicine, a specific treatment to target gout, corticosteroids to decrease inflammation and urate-lowering agents.¹ Surgical interventions may be required in cases unresponsive to medications, which involves decompression of affected tendons as well as removal of nonviable inflammatory tissues.¹

Are there complications if gout is left untreated?

If left untreated, the condition can progress involving persistent pain, tendon rupture and possible deformity of the joints which may require surgery. Surgery brings its own complications, including infection, nerve damage, and tissue scarring. ¹

What is the relationship between pseudogout and tenosynovitis?

What is pseudogout?

Pseudogout or CPPD, as it is known, is a rheumatologic condition which resembles gout; however, the crystals which deposit in the connective tissue surrounding bones in synovial joints differ.¹² CPPD is characterised by crystals of calcium pyrophosphate dihydrate. It causes sudden onsets of sharp joint pain, inflammation and stiffness with episodes lasting days or weeks. CPPD disease is a clinically diverse condition which can present in several forms

1. Acute CPP crystal arthritis
2. Osteoarthritis with CPPD disease
3. Chronic CPP inflammatory arthritis and
4. Crowned dens syndrome¹³

What is the mechanism of tenosynovitis in pseudogout?

The pathophysiology of Pseudogout is still surrounded by mystery. At a cellular level, adenosine triphosphate (ATP) is a molecule which acts as the energy supply to drive many processes within cells. It is made up of 3 components, including phosphates. Pseudogout is thought to occur due to an imbalance between the overproduction of pyrophosphate and the levels of pyrophosphatases in diseased cartilage, mainly due to decreased removal or use of pyrophosphates.¹⁵ As pyrophosphate deposits in the synovium and adjacent tissues, it binds with calcium to form CPP.¹²  

Tenosynovitis-related pseudogout develops when the immune system attempts to remove the CPP crystal deposits in the connective tissue by performing phagocytosis( white blood cells killing and removing foreign cells). This initiates an inflammatory cascade, releasing pro-inflammatory cytokines (involved in the upregulation of inflammatory reaction) in the localised tissue. ¹⁵

What is the clinical presentation of pseudogout-related tenosynovitis?

A large number of patients present with underlying joint disease or metabolic abnormalities predisposing to CPP deposition, including osteoarthritis, trauma, surgery, or rheumatoid arthritis.¹³ Many patients present with carpal or cubital tunnel syndrome.¹² Multiple joints are commonly involved, and the episodes of inflammation may present in a nonsynchronous, waxing, and waning clinical course lasting several months.  The majority of patients present with dull pain, mild swelling, stiffness and a reduced range of motion. Tenosynovitis-induced pseudogout commonly affects larger and weight-bearing joints, including the hips, knees, shoulders, and wrists.

How is pseudogout diagnosed?

Due to their innate similarities, it can be clinically difficult to distinguish between Pseudogout and Gout. Therefore, there are two main methods to aid in diagnosis.

• The most useful diagnostic tool is to perform an arthrocentesis ( the aspiration of synovial fluid from a joint). The fluid is analysed under a polarising microscope to determine the presence of CPPD crystals. characteristic features of CPP crystals are weak positive birefringent crystals, mostly rhomboid- or rod-shaped¹⁵
• X-ray can identify calcifications ( crystal deposits) in cartilage and can demonstrate the extent of damage
• Ultrasound, MRI and CT can be useful tools in cases of suspected CPPD tenosynovitis in atypical sites

How is pseudogout-related tenosynovitis managed?

The treatment for patients is based on initially decreasing inflammation at the site and stabilising any underlying metabolic disease contributing to the CPPD deposition. ¹²  These include:

1. NSAIDs for patients presenting with acute inflammation and involvement of 3 or more joints
2. Colchicine daily, those with recurrent episodes
3. Intra-articular glucocorticoid administration, for acute flares and involvement of 2 or fewer joints when septic arthritis has been ruled out. ¹²
4. Rest

What is the long-term prognosis of CPPD tenosynovitis? Are there any long-term complications?

While there are numerous medications available that directly target decreasing serum urate levels and preventing urate crystal formation, currently, no therapies directly targeting CPP crystal deposition are available. Consequently, the treatment of CPPD relies on treating predisposing metabolic diseases, tissue inflammation, and symptoms.¹²

Acute CPPD is usually self-limiting, and symptoms resolve after treatment. Chronic CPPD cases and those with induced tenosynovitis can take months to resolve, especially if overlapping with other co-existing arthritic conditions. Such patients may continue to experience CPPD symptoms in an unpredictable manner over their lifetime.¹²

Complications include:

1. The breakdown of synovial tissue causes irreparable joint damage
2. Development of crystal nodules known as ‘tophi,’ which can add to further degeneration of the joint and loss of functionality

How is a differential diagnosis between gout and pseudogout made?

The most useful and accurate investigation for differentiation is a high-resolution ultrasound scan

Laboratory distinctions: Following synovial fluid aspiration and analysis under polarised microscopy, Gout can be recognised via its needle-like Uric Acid crystal appearance; pseudogout can be recognised via its rhomboid/rod-shaped calcium pyrophosphate (CPP) crystals.

There are several clinical distinctions between the two conditions:

Gout is a treatable condition. Pseudogout, we can treat the symptoms and any predisposing diseases. Location. Gout occurs most commonly in one joint only- in the big toe, foot, ankle, knee, wrist, elbow, or finger. Pseudogout can affect numerous joints at once- the knee, wrist, ankle, and spinal ligaments.

Are there causes other than gout/ pseudogout for tenosynovitis?

Yes, there are several different possible causes of Tenosynovitis.

1. Infectious causes- Many common infections can spread to your synovial membrane most frequently detected organisms include Staphylococcus aureus, Pseudomonas aeruginosa, Beta haemolytic streptococcus, Eikenella and, following an animal bite, Pasturella multocida⁵
2. Autoimmune causes – Tenosynovitis is noted in 87% of patients suffering from rheumatoid arthritis¹
3. Overuse of the joint - Frequent repetitive movements causing inflammation of the synovial sheath, often referred to as repetitive strain injury
4. Trauma to the joint – injury which has caused damage to the tendons or surrounding tissue can cause tenosynovitis

What are the treatment and management strategies for tenosynovitis?

Conservative management is recommended alongside pharmacological treatments as described above. This includes rest, physical therapy and wearing of joint support aids.¹⁵ Surgical interventions may become necessary in rare, extreme cases, when no improvement can be seen following months of conventional treatment.  Surgical intervention may involve the release of affected tendons or possible debridement of the inflamed tissues.¹ Prevention strategies include daily doses of colchicine for those who suffer frequent episodes. For those with a gout-induced tenosynovitis, it is advised to take a low-purine diet as this will assist in reducing uric acid buildup.⁶

What is the prognosis of tenosynovitis?

The prognosis for individuals with tenosynovitis related to gout or pseudogout is generally positive. The majority of individuals who suffer from the condition make a full recovery and return to normal day-to-day life with no long-term effects.⁶ If cases of tenosynovitis do not subside following all treatment lines, it can then progress to stenosing tenosynovitis. This causes permanent contracture or shortening of muscles and tendons, preventing normal movement of joints, most commonly seen in fingers known as ‘trigger finger’.¹⁶ Adherence to the treatment regimen is essential in order to prevent disease progression.

Summary of gout/pseudogout causing tenosynovitis

There is a very clear documented relationship between Gout/ Pseudogout and the inflammatory response induced condition of Tenosynovitis. Early diagnosis of the true cause of Tenosynovitis allows the correct line of treatment to be prescribed and in the long term, prevents further episodes from occurring or any additional complications. Age and other co-morbidities, including rheumatoid arthritis, are big risk factors in the likelihood of developing Tenosynovitis. Although a lot more research is required in the field, there is ongoing research into the area of arthritis serum biomarkers and also for the development of specific Pseudogout treatment aimed at breaking down excess phosphate in the body. Overall, the prognosis for both conditions is excellent.