The joints are enlarged at birth. Motor milestones are often delayed secondary to joint deformities. Progressive and painful joint enlargement can be accompanied by flexion contractures. Muscle atrophy may then result from disuse. Due to the kyphoscoliosis, the trunk appears short in later childhood.
Clubfoot can be present.
Adult height is between 100-145cm. It is important for individuals with Kniest dysplasia to have their cervical or neck vertebra followed with careful neurologic exams, x-rays of the neck in flexion and extension, and MRIs if warranted. Coronal clefts of the lumbar vertebrae may be seen. Kniest dysplasia is inherited in an autosomal dominant manner. Prenatal diagnosis has been made by second trimester ultrasound.