Description
SMD-K is an extremely rare form short-trunk dwarfism. The arms and legs are proportionally longer than the body trunk.
Spondylo means spine. Only the spine and bone ends (metaphyseal) are affected, though there are some associated hip problems (see description and potential complications below). It is one of the more mild forms of dwarfism.
Symptoms
Clinical signs of SMD-K are varied but include changes in BOTH the vertebrae and metaphyseal layer in the long bones. X-rays show flattened bone ends particularly in the femur causing Coxa Vara (hips facing towards the body) and the vertebrae are flattened. Back problems involving curved spines such as kyphosis and scoliosis (also known as kyphoscoliosis) are common.
There are no known metabolic changes associated with SMD-K.
Genetics
SMD-K has a dominant inheritance. You only need to inherit the gene from one parent to have SMD-K.
Is Intelligence affected?
People with SMD-K usually have normal intelligence.
Expected Height
Height can vary, but is usually around 130-150 CM (between 4 and 5 feet).
General Medical Care
Neck and vertebrae An evaluation of the C1 and C2 should be done to detect odontoid hypoplasia; spinal fusion may be indicated. Even though a spinal fusion may not be needed, lax ligaments in the neck could lead to spinal injury during anesthesia, contact sports, and car accidents.
Kyphoscoliosis (curved spine) is a common complication and it should be monitored. In addition, there have been some reports of cervical spine instability.
Coxa Vara, hips set at a at the wrong angle, towards the body (average is about 135 degrees), is usually present. It causes a waddling gait and can cause premature hip degeneration.
Always check with your medical doctor to evaluate your particular health care needs.
General Precautions
Due to neck instability, persons with Kniest should exercise caution to avoid activities/sports that could result in trauma to the neck or head.
More Information
KSG website can not keep track of the rapidly changing science! We suggest you visit the following sites for the most recent information:
LPA Medical resource center Kniest page: is an in-depth reference guide to the around 300 different types of dwarfism, intended not just for the lay person, but for medical professionals as well. The MRC also contains information about anesthesia, surgeries and procedures, common questions and a Frequently Asked Questions (FAQ).
Online Mendelian Inheritance in Man (OMIM) Kniest Page: MedlinePlus is an online health information resource for patients and their families and friends. It is a service of the National Library of Medicine (NLM), the world’s largest medical library, which is part of the National Institutes of Health (NIH).
Search https://medlineplus.gov/ . MedlinePlus is an online health information resource for patients and their families and friends. It is a service of the National Library of Medicine (NLM), the world’s largest medical library, which is part of the National Institutes of Health (NIH).
Recent Research
Search Pubmed for recent articles on Spondylometaphyseal Dysplasia. PubMed® comprises more than 36 million citations for biomedical literature from MEDLINE, life science journals, and online books.