Adolescent-onset Local Kyphosis with Anterior Column Hypoplasia and Subluxation of the Facet Joints of the Lumbar Spine: A Case Report

INTRODUCTION: Hypoplasia of the anterior portion of the vertebral body is a relatively rare subtype of juvenile vertebral deformity. The common manifestations of this type of deformity are scoliosis and kyphoscoliosis, while kyphosis without scoliosis is rare. Here, we present a very rare case of adolescent-onset local kyphosis with anterior column hypoplasia and subluxation of the facet joints of the lumbar spine, as demonstrated by dynamic lateral radiograms, which was successfully treated by spine-shortening osteotomy. CASE REPORT: A 16-year-old male adolescent presented with low back pain with progressive protrusion of the lumbar spinous process 3 years before the first visit. The protrusion was not found in his back until the age of 13 years. His chief complaint was lower back pain and a protruding spinous process in the upper lumbar spine. The anteroposterior radiogram of the whole spine revealed no obvious scoliosis. The lateral radiogram showed hypoplasia of the anterior portion of the L2 vertebral body with local kyphosis at L1–3 of 23°. The global alignment was posteriorly shifted, with hypokyphosis of the thoracic spine and hyperlordosis of the lower lumbar spine. In the dynamic lateral radiograms, the facet joints at the L2–3 spinal level were subluxated in the flexed position. Computed tomography showed symmetrical hypoplasia of the anterior portion of the vertebral body of L2. Spine-shortening osteotomy at L2 and L1–3 posterior fusion was performed for local stabilization and correction of sagittal malalignment. The lateral radiogram at the 2-year post-operative follow-up demonstrated that the global alignment was normal, with local kyphosis at L1–3 of -2°. The improvement of hypokyphosis of the thoracic spine and hyperlordosis of the lower lumbar spine was achieved. CONCLUSIONS: Adolescent-onset local lumbar kyphosis with anterior column hypoplasia and segmental subluxation of the facet joints is very rare. Local correction by spine-shortening osteotomy with short fusion can also improve the global alignment.