The goal of operative treatment of ankle fracture are to obtain an anatomical reduction and rigid fixation to ensure a healed fracture and normally functioning recovery. Irreducible ankle fracture or fracture-dislocation is seldom encountered in clinical practice. Two cases of irreducible ankle fractures are presented. They are different from previous cases reported in the literature. During operation we recognized that the extensor tendons were entrapped in the distal tibiofibular joint under the extensor retinaculum. The reducible ankle fractures reported in the literature, together with the two cases in this report, are classified into three categories. Type I is a medial malleolar fracture with deltoid ligament or posterior tibialis tendon interposition. Type II is an irreducible fracture dislocation of the ankle due to posterior dislocation of the fibula. Type III is a diastatic ankle fracture with extensor tendons entrapped in the distal tibiofibular joint and restricted by extensor retinaculum. The mechanism of the irreducible ankle fracture is discussed and correlated with Lauge-Hansen classification and mechanism.