The primary trapeziometacarpal ligament is also known as the anterior oblique ligament. It stabilizes the thumb's trapeziometacarpal joint. This joint connects the trapezium to the first metacarpal bone. The trapezium is a small carpal bone located below the thumb. The trapeziometacarpal ligament originates on a ridge-like bump on the trapezium. This is known as a tubercle. It inserts into the base of the first metacarpal bone. The ligament is stretched when the thumb is extended or rotated inward. It provides mobility but it also prevents dislocation. In some cases, it may remain partly uninjured even if the joint is dislocated. Osteoarthritis of the joint is common. Serious cases can be treated with surgery. The most common surgical technique involves trapeziectomy. This refers to removing the trapezium.