De Quervain's Tenosynovitis
De Quervain's Tenosynovitis is a condition where the sheath or Synovium that surrounds the two tendons that run between the wrist and thumb is inflamed. Pain along the side of your wrist aggravated upon thumb movement and making a fist.
Wearing a brace that would keep the thumb in an extended position with wrist in a neutral position to reduce swelling and limit motions that agitates the tendon.