Disarticulation at the ankle using an anterior flap

Abstract

Disarticulation has been carried out in ten ankles in nine patients in whom it was not possible to use a heel flap. Four patients were able to walk with a prosthesis which gave satisfactory function. In five who were bedridden, healing was achieved and was of sufficient quality to allow transfers. There was no operative morbidity or mortality.This technique can be used instead of a transtibial amputation if necrosis or ischaemia of the heel is a contraindication to conventional Syme's amputation. J Bone Joint Surg [Br] 1999;81-B:617-20. Received 1 October 1998; Accepted after revision 1 December 1998An anterior skin flap taken from the instep can be used to cover the bone ends in disarticulation of the ankle when ulceration or necrosis of the heel prevents the use of the heel flap for a conventional Syme's amputation. This technique was originally described by Baudens 1 and quoted byMurdoch. 2 It can be carried out under regional anaesthesia.It is well tolerated in the unfit patient and avoids many of the problems of the Syme's procedure. Ground contact is acceptable and there are some advantages for the fitting of a prosthesis. Patients and MethodsExperience in the rehabilitation of a 24-year-old patient in whom disarticulation of the ankle had been carried out using skin from the instep rather than a heel flap after a compound fracture of the calcaneum, led us to the use of this method in patients with necrosis of the heel. Patients selected for this procedure had intact skin on the proximal part of the instep but ulceration, fissuring necrosis or infection involving the heel. There was absence of pain at rest, adequate perfusion, colour and temperature with evidence of flow in one of the three arteries to the ankle on testing with a hand-held Doppler apparatus. In one patient a transcutaneous oxygen measurement of 40 mmHg was found in the skin at the instep. A systolic pressure of 30 mmHg in one or more vessels of the ankle is ideal and a transcutaneous PO 2 of 40 mmHg is necessary.Before operation, sepsis was controlled by local cleansing and antibiotics. Diabetic control was optimised. The patients' nutrition was assessed and protein deficiency corrected when possible. Renal insufficiency and cardiac and pulmonary disease were treated. Subcutaneous heparin or fragmin were used to prevent venous thrombosis and embolism. Prophylactic antibiotics including metronidazole and often cefotaxine were used over the perioperative period. Anaesthetic assessment was carried out by ECG and pulmonary function tests, usually leading to the selection of epidural or spinal anaesthesia. Operative technique. The design of the long anterior flap, as an alternative to the Syme's heel flap, was tested initially on cadavers. A rectangular anterior flap based on the tip of the malleoli provided the best cover.The operation is carried out with the patient supine. A tourniquet is applied above the knee, but not inflated. The skin is prepared with povidone iodine. The skin flaps, based on the prominence of the medial and lateral mall...