KFS, described by Klippel and Feil in 1912, comprises three characteristic deformities: a short neck, a low dorsal hairline, restricted neck mobility. It may be associated with variants of cerebral palsy, mental retardation, and a wide variety of other physical deformities.

It is the result of synostosis (joining) of several cervical (neck) vertebrae, which may or may not be deformed. Other associated abnormalities reported include those related to urological (urinary system), neurological (brain and spinal cord) , cardiopulmonary (heart and lung) and locomotor (bone and joints including muscles and tendons) deformities, which significantly increase the morbidity.

Cause

There is a hypothesis that KFS could be the result of an interruption of the early embryonic blood supply in the subclavian (shoulder) arteries, the vertebral (neck) arteries and/or their branches. It is supposed that the occlusions occur at specific locations in these vessels during or around the sixth week of embryologic development and produce predictable patterns of defects.