A 28-year-old male labourer presents to the emergency department after a fall from a 10-foot scaffold onto his outstretched right arm. On examination, the right forearm shows gross deformity with the wrist in a 'dinner fork' appearance. Plain radiographs reveal a fracture of the distal radius with dorsal displacement and angulation of the distal fragment, with the fracture line extending into the radiocarpal joint. The ulna is intact. Which classification best describes this fracture pattern?