Thumb tenosynovitis is a type of stenosing tenosynovitis, usually seen in cases of hand injuries, overstrain, etc. It can be recovered through conservative treatment or decompression therapy. Thumb tenosynovitis specifically refers to tenosynovitis of the flexor digitorum longus muscle at the head of the first metacarpal bone. There is a kind of tunnel between the tendon sheath and the bone, and due to excessive mechanical friction between the tendons and ligaments leading to tendon sheath oedema, hyperplasia, and compression of the tunnel, which in turn causes chronic aseptic changes. It is mostly seen in people with hand injuries and overstrain, such as long-term heavy manual labor and prolonged use of the mouse. Initial treatment is mostly conservative, such as adjusting hand movement and splinting. If conservative treatment is ineffective, stenosing tenotomy and decompression may be considered, and the specific treatment plan should be discussed with the doctor.