The right thumb x-ray shows an intra-articular fracture of the base of the thumb metacarpal, consistent with a Bennett’s fracture.
Bennett’s fracture is an oblique fracture of the base of the 1st metacarpal involving the 1st carpometacarpal joint. It is often unstable due to distraction of the distal fragment by the Abductor Pollicis Longus muscle.
Reference: Grainger & Allison’s Diagnostic Radiology Essentials.