De Quervain’s tenosynovitis is an inflammation of the sheath that surrounds the thumb’s tendons, called the synovium, which results in pain and difficulty moving the thumb. The condition is often caused by repetitive motions such as gripping or twisting, which can lead to irritation and swelling of the tendons. It is more common in women over the age of 40. Other factors that may contribute to the development of De Quervain’s tenosynovitis include rheumatoid arthritis, pregnancy or having recently given birth, and previous injury to the hand or wrist. It is important to note that the symptoms of De Quervain’s tenosynovitis can be similar to other conditions such as carpal tunnel syndrome, and it is always best to consult with a doctor for proper diagnosis and treatment.