Physical Characteristics of Kniest Dysplasia

Kniest dysplasia is a rare, severe form of cartilage dysplasia that causes short-stature, spine deformities, near-sightedness, and large, stiff joints.

Face and Skull:

• Large head relative to trunk
• Round and flat face
• Wide, prominent forehead and eyes
• Flattened nose
• Wide mouth
• Depressed chin
• Cleft palate present in 50% of patients.

Trunk, Chest and Spine:

• Short trunk
• Progressive kyphoscoliosis
• Pigeon chest with thoracic kyphosis and lumbar lordosis

Arms and legs:

• At birth, short limbs compared to the torso; proportions change as trunk shortens and becomes kyphotic.
• Rhizomelic shortening of the limbs
• Knock-knees
• Flat feet
• Widened joints in the arms and legs, oftentimes with painful contractures and limited motion

What are the x-ray characteristics?

The radiographic features of Kniest patients include broad and short femoral necks. Retarded ossification of capital femoral epiphyses usually appearing in ages 2-3 is typical. Ultimately, the epiphyses are large and flattened. Platyspondyly with anterior wedging of vertebral bodies is also characteristic. In newborns, lumbar bodies exhibit coronal clefts. The ilia are broad ilia with hypoplasia of the basilar portions. By age 3, the pelvis has “dessert-cup” shape. The tubular bones are short with flared metaphyses and large, deformed epiphyses. Hand radiographs reveal osteoporosis, large carpal centers, and “bulb-like” interphalangeal joints with narrow joint spaces.