Which fracture is a fracture/dislocation of the thumb at the carpometacarpal joint?

Which fracture is a fracture/dislocation of the thumb at the carpometacarpal joint?

• A. Rolando
• B. Gamekeeper's
• C. Barton's
• D. Bennett

Answer: (D)

The main idea is a fracture at the base of the first metacarpal with a dislocation at the thumb’s carpometacarpal joint. This is classic for a Bennett fracture. It usually results from an axial load on a partially flexed thumb (common with a punch or fall onto the thumb), causing a fracture line through the base of the first metacarpal with a small fragment pulled along with the trapezium by ligamentous attachments. The rest of the metacarpal shaft tends to displace dorsally and radially because of the pull of the abductor pollicis longus and related structures, making the joint unstable. Clinically and on imaging, you’ll see an intra-articular fracture at the base of the first metacarpal with dislocation at the thumb CMC joint. This pattern is unstable, so it typically requires prompt reduction and stabilization to preserve joint congruity and later grip strength; otherwise, it can lead to arthritis. To contrast, a Rolando fracture is a comminuted intra-articular base fracture of the first metacarpal (not the classic dislocation pattern described above), a Gamekeeper’s thumb is an injury to the UCL at the MCP joint, and a Barton's fracture is a distal radius/ radiocarpal joint fracture-dislocation, not involving the thumb CMC joint.

The main idea is a fracture at the base of the first metacarpal with a dislocation at the thumb’s carpometacarpal joint. This is classic for a Bennett fracture. It usually results from an axial load on a partially flexed thumb (common with a punch or fall onto the thumb), causing a fracture line through the base of the first metacarpal with a small fragment pulled along with the trapezium by ligamentous attachments. The rest of the metacarpal shaft tends to displace dorsally and radially because of the pull of the abductor pollicis longus and related structures, making the joint unstable.

Clinically and on imaging, you’ll see an intra-articular fracture at the base of the first metacarpal with dislocation at the thumb CMC joint. This pattern is unstable, so it typically requires prompt reduction and stabilization to preserve joint congruity and later grip strength; otherwise, it can lead to arthritis.

To contrast, a Rolando fracture is a comminuted intra-articular base fracture of the first metacarpal (not the classic dislocation pattern described above), a Gamekeeper’s thumb is an injury to the UCL at the MCP joint, and a Barton's fracture is a distal radius/ radiocarpal joint fracture-dislocation, not involving the thumb CMC joint.