We report a series of three cases of progressive anterior vertebral fusion diagnosed and monitored in our establishment. This very rare condition was discovered in young children while exploring a spinal deformity. With X-rays of the thoracolumbar spine it was possible to make a positive diagnosis and ensure follow-up. The radiographic semeiotics are characteristic and combine anterior pinching of the disc, well-delimited erosion of the anterior vertebral corners and anterior then posterior intervertebral ankylosis. MRI is very useful for assessing the extent of the intervertebral ankylosis and the condition of the residual discs, without irradiation. The condition develops over several months or years. Conservative treatment is usually sufficient.