Radiological Investigation of a Case of Sacro-coccygeal Agenesis

Abstract

Congenital defects of the lower spine extend in a cranio-caudal direction and may be regarded as a pathological progression of a phylogenetic process. Agenesis may be complete up to any level or may be partial (dysgenesis). The classification of Foix and Hillemand (1924) attempts to correlate the extent of the vertebral defect to the associated neurological changes and other complications. For the limited purpose of this presentation the following main grouping already suggested by Freedman (1950) will be adequate. (1) Presence of part of the sacrum or of a sacralised last lumbar vertebra to complete the pelvic ring and allow weight transmission into the lower extremities. (2) Total absence of bone between the ilia which are then in apposition medially and may be fused. Weight transmission is interrupted though a linkage by strong ilio-lumbar ligaments has been reported (Higgs, 1924). This paper has confined its interests to the second group, as the following case belongs to it. Savitree, an Indian girl of nine months was referred to the X-ray department at the Georgetown Hospital in British Guiana. She was of normal intelligence but unable to use her lower limbs which were fixed in flexion and external rotation. Her abdomen was short, her pelvis narrow and a small gibbus projected from the lower part of her back (Fig. 1). There was an agenesis of the sacrum and coccyx and of the lumbar spine below a rudimentary second body.