De Quervain’s Tenosynovitis is inflammation of tendons of two muscles in the hand region called abductor pollicis longus and extensor pollicis brevis.
These two tendons run side by side in a sheath and are lined with a lubricating material called tenosynovium. Tenosynovium normally helps the two tendons glide over each other smoothly and when there is inflammation of the tenosynovium, tenosynovitis is said to occur. Aside inflammation, there can also be thickening of the tendons. These processes, inflammation and thickening cause pain and sometimes noises around the wrist region as the hand is being used.