This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
When amputation is performed at the ankle it is usually either by the method of Syme or that of Pirogoff.
"A transverse incision should be carried across the sole of the foot from the tip of the external malleolus or a little posterior to it (rather nearer the posterior than the anterior edge of the bone) to the opposite point on the inner side, which will be rather below the tip of the internal malleolus." The extremities of this incision are connected by another directly across the front of the ankle-joint. The anterior capsule is then divided and the lateral ligaments divided from within outward. The foot being bent down, the tendo calcaneus is cut close to the bone and the calcaneum dissected out. The malleoli are then to be cleared and sawn off with a thin slip of the articular surface of the tibia (Fig. 575).
Fig. 575. - Syme's amputation of the ankle.
Remarks: The incision across the sole must not go too far back on the inner side, as the internal calcanean branch of the external plantar artery will be divided and the integrity of the flap threatened. In clearing the calcaneum it is rather an advantage, especially in young people, to take off a thin slice of bone with the tendo calcaneus. In removing the slice from the tibia as little as possible (in growing patients) should be removed, to avoid injuring the epiphyseal cartilage. In dissecting back the flap of the heel, the point of the knife is to be kept close to the bone to avoid cutting the vessels in the flap itself.
The sole incision is carried across from just in front of the external malleolus to just in front of the internal. The anterior incision is made across the front of the joint and the foot disarticulated by dividing the capsular and lateral ligaments. The foot is then bent down and the calcaneum sawn through the line of the sole incision. A slice is to be removed from the tibia and fibula and the sawn surface of the calcaneum brought up and sutured with chromic catgut (or other) sutures to the sawn surface of the tibia (Fig. 576).
Fig. 576. - Pirogoff's amputation of the ankle.
In bringing up the calcaneum to the tibia it may be found difficult to approximate them without undue tension on the tendo Achillis. To provide against this common difficulty it is customary to place the saw on the upper surface of the calcaneum well behind (a finger-breadth) the joint. Also to dissect back the heel-flap .50 to 1 cm. (1/4 to 1/2 in.) so that more of the calcaneum can be removed. A larger slice is also taken from the tibia than in Syme's amputation. If the tension remains too great on the tendo calcaneus it is to be divided.