Introduction

The meaning of the word "tenosynovitis" can be deduced from its constituent parts..  "Teno" means tendon, which is the tough tissue that connects muscles to bones. "Synov" refers to the synovium, a fluid-filled sac that cushions the tendon and helps it move smoothly.  "It" means inflammation or swelling.

Tenosynovitis is a condition that causes pain, swelling, and limited movement. It happens when the protective covering around your tendons, called the tendon sheath, becomes inflamed. Tendons are the tough cords that connect your muscles to your bones, and the sheath helps them glide smoothly. When the sheath gets inflamed, it can be hard to perform everyday activities like gripping objects, walking, or writing. While tenosynovitis often affects the hands, wrists, and feet, it can occur in other parts of the body as well.¹

There are three main causes behind this condition: overuse, trauma, and infection. Overuse happens when you repeat the same motion repetitively, putting too much stress on the tendon. Trauma can be caused by a direct injury, like a fall, or by too much force on the area. Infections occur when bacteria inflame the tendon sheath.. It is important to determine the cause of tenosynovitis so doctors can treat it properly.¹

This article explores tenosynovitis, a condition that causes pain, swelling, and difficulty moving due to inflammation of the tendon’s protective covering. The main focus is to explain the causes of tenosynovitis in a simple way, while also touching on its symptoms, diagnosis, treatment, and prevention.

Overuse as a cause of tenosynovitis

Overuse is a major cause of tenosynovitis. Repeating the same movements continuously puts constant stress on your tendons and the protective sheaths around them. This constant stress can cause irritation, inflammation, and swelling. Think of it like repeatedly bending a paperclip – eventually, it weakens and can even break. Similarly, overuse can gradually wear down the tendon sheath, making it more prone to injury.. Certain jobs and activities that involve repetitive hand or wrist motions increase your risk. For example, people who spend a lot of time typing on computers, athletes who play sports like tennis or golf, and those who work on assembly lines doing repetitive motions are all at higher risk. Two specific conditions, De Quervain’s tenosynovitis and trigger finger, are often linked to overuse. De Quervain’s affects the thumb tendons, making gripping and wrist movements painful.⁵

Trigger finger affects the finger tendons, causing stiffness, pain, and a catching or locking sensation.⁶ Early signs of overuse-related tenosynovitis include pain and tenderness along the affected tendon, swelling or warmth, stiffness, and sometimes a clicking or snapping feeling. Catching these symptoms early is important to prevent the inflammation from getting worse and causing long-term problems.^4,14

Trauma as a cause of tenosynovitis

Tenosynovitis can also be caused by injuries. When you experience a direct injury like a fracture, sprain, or a hard blow, it can damage the tendon sheath, the protective covering around your tendons. This damage triggers inflammation and swelling. Akin to bruising, the injured area swells up as your body tries to heal. When a tendon or its sheath is suddenly injured, your body's natural healing process starts, but this can cause pain, stiffness, and make it harder to move the affected area. Sometimes surgery can lead to tenosynovitis from complications such as scarring or the injury not healing correctly. Factors that increase the risk of developing tenosynovitis include not letting an initial injury heal correctly, putting too much stress on the tendon during recovery, and not following your doctor's instructions for rehabilitation. If the inflammation isn't treated properly, it can persist and cause chronic problems, such as reduced flexibility and thickening of the tendon.⁴

Infections as a cause of tenosynovitis

Sometimes, tenosynovitis is caused by infection. This occurs when bacteria, usually Staphylococcus or Streptococcus, get into the tendon sheath.. This is different from overuse or injury, it's an actual bacterial invasion. The bacteria often enter through a puncture wound, such as an animal bite, a needle stick, or a deep cut. Think of it like any other infection you might get, but this one specifically targets the tendon sheath. The infection can also spread from nearby infected tissues, such as if you have cellulitis or a bone infection, or even through the bloodstream.

When you have infectious tenosynovitis, you'll likely experience intense pain, redness, swelling, and warmth around the affected area.  In more serious cases, you may see pus or drainage. You may develop a fever.. Because this is a bacterial infection, it's important to seek treatment quickly. If left untreated, the infection can cause problems such as tendon death, permanent stiffness,  and it may spread to other parts of the body. Treatment involves antibiotics to kill the bacteria; sometimes surgery is needed to drain pus and relieve pressure. Ignoring this type of tenosynovitis can lead to long-term damage and make it difficult to use your hand or joint properly, so it's essential to see a doctor immediately should you suspect an infection.⁴

Diagnosis and differentiation

Determining if you have tenosynovitis and what's causing it involves several steps. Doctors will start with a physical exam, checking the affected area for pain, swelling, warmth, and ease of movement. They'll ask you about any tenderness along the tendon sheath, and if it looks like an infection, they'll look for redness and pus. Doctors may use imaging tests to get a better look at what's going on. X-rays and ultrasounds can rule out broken bones or other bone issues, while ultrasounds will show fluid buildup around the tendon sheath, which is a sign of inflammation.

For more serious or long-lasting cases, an MRI might be used to give a more detailed picture of the soft tissues. If the doctor suspects an infection, they'll likely order blood tests. A complete blood count can show if your body is fighting an infection; blood cultures can help identify the specific bacteria causing it. It's important to determine whether the tenosynovitis is from overuse, an injury, or an infection because each cause requires a different treatment. Overuse might just need rest and physical therapy, while an infection will require antibiotics, and sometimes surgery to drain pus.^7,8,9

Treatment approaches

How tenosynovitis is treated depends on its cause, whether it's from overuse, an injury, or an infection. Each cause demands a specific approach to ease the pain, reduce swelling, and get you moving normally again. For overuse, the main goal is to rest the affected tendon. This means refraining from using the affected tendon and keeping the area still with a splint or brace. Physical therapy is also important, as gentle stretches and exercises are used to help the tendon heal. Pain and swelling are often managed with over-the-counter pain relievers like paracetamol and ibuprofen. In more stubborn cases, the doctor may give a corticosteroid injection to reduce inflammation, but these are used sparingly because they can weaken the tendon if used too often. If tenosynovitis is caused by an injury, it's important to act quickly to prevent lasting damage.

The RICE method – Rest, Ice, Compression, and Elevation – is typically the first step to reduce swelling and pain. If the swelling doesn't go down or the tendon sheath thickens, surgery may be needed to release the tendon sheath and prevent problems such as adhesions or tendon entrapment.  After surgery, rehabilitation is key to regaining strength and movement.  In the case of an infection, getting medical help right away is vital to stop the infection from spreading and causing serious tendon damage. Antibiotics are the main treatment, pills for milder cases and IV antibiotics for more severe infections. If there's considerable pus or severe inflammation, surgery may be needed to drain the infected fluid and relieve pressure. Delaying treatment for an infection can lead to permanent stiffness, reduced function, or even a widespread infection, so early diagnosis and treatment are crucial.  No matter what cause, it's important to recognise tenosynovitis early and seek treatment to ensure a full recovery and avoid chronic issues.¹,^10,14

Prevention strategies

Preventing tenosynovitis is about minimising strain on your tendons and avoiding infections.  There are several things you can do to lower your risk. If you have a job involving repetitive movements, such as typing or factory work, setting up your workspace ergonomically is key. This may mean using an ergonomic keyboard, adjusting your desk height, and taking regular breaks to stretch your hands and wrists. This helps prevent overuse.  Athletes and anyone participating in physically demanding activities should always warm up and stretch before exercising or heavy lifting. Stretching increases flexibility and blood flow to tendons and helps prevent minor injuries that can lead to tenosynovitis. Strengthening the muscles around your tendons helps share the workload and reduce stress on the tendon sheath.  Preventing infections is also important, especially if you're at risk of cuts or puncture wounds. Cleaning, disinfecting, and covering any cuts or bites immediately helps keep bacteria out. People in healthcare, agriculture, or other high-risk jobs need to be extra careful and consult a doctor if a wound turns red, swollen, or painful. Finally, regular check-ups are advisable, especially for athletes, manual labourers, and anyone with a history of tendon injuries. Catching tendon problems early allows for prompt treatment to prevent chronic issues from developing.. By taking these steps, you can significantly reduce your chances of developing this painful condition.¹⁴,¹

Conclusion

In summary, tenosynovitis can interfere with your ability to move and perform everyday tasks. It can develop from overuse,  repetitive motions such as typing or playing sports; from an injury, whether a direct blow or even a complication after surgery; or, less commonly, from a bacterial infection. Overuse causes inflammation and discomfort, while injuries lead to swelling and impaired tendon function. Infections, although less frequent, are serious and need quick treatment to prevent them from spreading. Doctors diagnose tenosynovitis using physical exams, imaging tests, and sometimes blood tests to figure out the cause and choose the right treatment. Treatment can range from rest, physical therapy, and pain relievers for overuse, to surgery and antibiotics for injuries and infections. There are precautions you can take to prevent tenosynovitis, such as setting up your workspace ergonomically, warming up properly before exercise, taking appropriate care of any wounds, and getting regular check-ups. Knowing what causes tenosynovitis, recognising the early signs, and following the right prevention and treatment plans can help you manage the condition and lessen its impact on your life.