The hand x-ray shows a dislocation of the thumb carpometacarpal (CMC) joint.

Thumb CMC joint dislocation is a rare injury, and the mechanism is an axial loading injury to a flexed thumb. The dislocation is mostly in the dorsal direction, with a clinical examination revealing bruising over the thenar eminence and an inability on the patient’s part to make a fist.

This injury can be treated with closed reduction and plaster immobilisation with the wrist in pronation and extension. Operative intervention is indicated if the reduction is unstable.

All patients need a referral to a hand surgeon.

Reference here.