Anatomical reduction and fixation of unstable ankle fractures is necessary to prevent post-traumatic arthritis. Malunion of the distal fibula in unstable ankle fractures can lead to late degenerative changes of the ankle. Late reconstruction of the ankle can improve its function and postpone the need for ankle fusion or replacement. We discuss three patients who presented with fibular malunion. All developed medial gutter opening, syndesmotic widening, and lateral shift and/or talar tilt. Surgery involved an anteromedial approach to clean the medial gutter, an anterolateral approach to clean the syndesmotic interval, elongation of the fibula by six to eight millimetres and stabilisation with a cervical spine cage and a locked plate. After one year, all patients had radiologically demonstrated reduction of the talus in the mortise. Improved function was recorded at final follow up. The cage provides several advantages over other fixation methods, including osteoconductive properties, avoiding bone graft donor site morbidity, and the range of sizes allows the surgeon to adjust the amount of elongation. Using spinal cages to treat malunited fibula fractures has several advantages compared to bone graft and good results can be expected.