Congenital scoliosis with a unilateral bar.

Abstract

A review was made of all patients with congenital scoliosis seen at the Alfred I. duPont Institute, Wilmington, Del., from 1940 through 1966. There were 88 cases, which represented 12 per cent of the total number of patients with scoliosis. All patients without significant bony abnormalities were excluded from the congenital scoliosis series, as were all cases of infantile structural scoliosis (1) and patients with scoliosis secondary to specific metabolic abnormalities. In one significant group of 10 patients a serious curve had developed or was threatening before treatment. In this selected group a unilateral failure of segmentation of the posterolateral masses of two or more segments had resulted in a unilateral bar. History The significance of a unilateral bar has received relatively little attention in the literature. In 1960, Blount (2) described 4 cases with a unilateral bar and outlined a program of treatment for 3 of the patients. He emphasized the radiographic appearance of the unilateral failure of segmentation of the lateral and posterior elements. Goldstein (3) describes a patient who had a unilateral bar which became progressively worse in the absence of treatment. Winter et al. (4) also recognized the significance of such a bar. Radiographic Appearance The unilateral failure of segmentation of the posterolateral masses of the vertebrae has a characteristic roentgenographic appearance. On the affected side, the loss of growth potential is manifested by underdevelopment of the anatomic structures which failed to segment during embryological development. On the radiograph, particularly on the anteroposterior view, this has the appearance of a curvilinear bridge of bone at the apex of the concave portion of the curve. The pedicles are merged, forming the main component of the osseous bar. Disk spaces of the vertebral bodies may be narrowed or completely obliterated adjacent to the bar. On the opposite side, the anatomic structures should have a normal or near-normal appearance. The pedicles should appear as distinct individual structures and the disk interspaces have a relatively normal appearance. Thus, normal growth potential is preserved on the convex side. Abnormalities of the ribs, including fusion, are often seen adjacent to the unilateral bar. Other congenital defects such as cleft palate and clubfeet were noted in 30 per cent of the cases. The appearance of the bar is oftentimes accentuated in an oblique position, and oblique views are therefore routinely obtained. Most recent cases have been studied by laminagraphy, which offers a distinct advantage in ascertaining the structural defects. Cervical, thoracic, thoracolumbar, and lumbar vertebral bars have been seen. The number of cases is insufficient, however, for determination of any sites of predilection.