Thumb carpometacarpal joint

Cause, clinical and ultrasound findings

• Reasons for the injection include inflammatory arthritis and osteoarthritis.

• Functionally limiting pain and swelling should be present.

• Findings may include hypoechoic fluid and tissue (synovial proliferation) with or without neovascularity bulging out of the joint, bony protrusions (osteophytes) and cortical defects visible in two planes (erosions).