Atlantoaxial Instability
Atlantoaxial instability should be ruled out in all children with Kniest syndrome at diagnosis (see SED for details). The instability results from the skull moving abnormally in relation to the first cervical vertebra (called the ‘atlas’). It can cause spinal cord compression and impingement. Lateral neck x-rays in flexion and extension should be performed before administering a general anesthetic to these children.
Spine
Kyphosis occurs at the thoracolumbar junction in addition to scoliosis. No definite conclusions have been reached regarding the management of spinal deformities in Kniest children, but the same general principles of bracing apply to control the curve. Experience is limited on spine fusions in this group.
Joints
Stiffness, contractures and degenerative arthritis develop early in life. The cartilage of Kniest patients is soft and mechanically incompetent. Regular physical therapy is aimed at preserving movement and preventing further stiffness and permanent contractures.
