Role of computed tomography in selecting patients for hindquarter amputation.

Nine patients with soft tissue sarcomas close to the pelvic girdle and one patient with a primary malignant bone tumour of the pelvis were referred for consideration of hindquarter amputation. Patients were considered unsuitable for hindquarter amputation on clinical grounds if malignant disease infiltrated into the perineum or across the sacro-iliac joint. If disease in the femoral triangle extended above the inguinal ligament the tumour's operability was seriously questioned. Buttock tumours which had passed through the greater sciatic notch to become palpable on pelvic examination were also considered likely to be inoperable. On computed tomographic (CT) examination, tumours were considered inoperable if the psoas muscle was involved above the inguinal ligament, or if malignant disease involved the sacro-iliac joint, sacrum or perineal structures. Soft tissue tumours of the buttock extending significantly through the greater sciatic notch were also considered likely to be inoperable. Five patients thought suitable for hindquarter amputation on clinical assessment had no excluding features on CT; four undergoing hindquarter amputation were proven on histological examination to have good clearance of their tumours. In another patient, considered suitable for hindquarter amputation on clinical grounds, CT suggested that en bloc wide excision of the tumour was feasible enabling the affected limb to be preserved. Four patients after clinical examination were considered unsuitable for hindquarter amputation and in all cases inoperability was confirmed by CT. CT complements clinical examination and provides an objective and reliable means of selecting patients for hindquarter amputation which should avoid unnecessary surgical exploration.