What Is Hypochondroplasia?

Cartilage hypoplasia is also called fetal cartilage dystrophy, cartilage dystrophy dwarf, etc. It is a congenital abnormality due to the defect of ossification in the cartilage, which mainly affects the long bones. Good mental and physical development.

Basic Information

nickname

Fetal cartilage dystrophy, cartilage dystrophy dwarf

English name

achondroplasia

Visiting department

orthopedics

Multiple groups

Newborn

Common causes

Autosomal dominant inheritance, spontaneous gene mutation

Common symptoms

The trunk is disproportionate to the limbs, the skull is large and the limbs are short, the dwarf is deformed, etc.

Causes of cartilage hypoplasia

Cartilage hypoplasia is an autosomal dominant hereditary disease. A large proportion of cases are stillbirth or die in the neonatal period. The parents of most patients are developing normally, suggesting that it may be the result of spontaneous gene mutation. Molecular genetic studies have found that the gene encoding the fibroblast growth factor receptor has a point mutation in the short arm of the fourth pair of chromosomes.

Clinical manifestations of cartilage hypoplasia

At birth, the child's trunk is disproportionate to the limbs, the head is large and the limbs are short, and the trunk length is normal. The proximal part of the limb is affected more than the distal part. For example, the femur is shorter than the tibia and fibula, and the humerus is shorter than the ulna and radius. This feature becomes more obvious with age and gradually forms a dwarf deformity. Facial features include collapse of the bridge of the nose, protrusion of the lower jaw, and wide forehead. The middle finger and the ring finger cannot be moved together, which is called trident hand. May have flexion and contracture of the elbow joint and dislocation of the radial head. The lower limbs are short and curved in an arch shape, and the muscles are particularly bloated. The length of the spine is normal, but thoracic kyphosis can be seen in infancy. Infant occipital foramen stenosis is also more common in children, and the main symptoms are back and leg pain and intermittent claudication. Intelligence is generally unaffected.

Cartilage hypoplasia

Imaging examination

(1) The main findings of X-ray examination are the following: The skull is large, the forehead is prominent, and the parietal bone and occipital bone are also more prominent. Of 1/2. Such as associated with hydrocephalus lateral ventricular dilatation. The long bones become shorter, the bones thicker, the medullary cavity becomes smaller, and the callus can be fragmented or irregular. At the knee joint, the bone ends are usually "V" shaped, and the ossification center of the epiphysis is embedded in this V-shaped notch. Because the ossification center is close to the backbone, the joint space is widened. The lower limbs are arched, with the fibula longer than the tibia and the upper limb ulna longer than the radius. The thickness of the vertebral body is reduced, but the reduction of the total length of the spine is relatively less than that of the limbs. From the first lumbar spine to the fifth lumbar spine, the distance between the vertebral arches gradually decreases. Myelography revealed a narrow spinal canal with multiple disc herniations. The pelvis is narrow, the skeletal bones are flat and round, each diameter is small, the acetabulum moves backward, close to the ischial notch, there is hip varus, and the size of the acetabulum and the femoral head is asymmetric. The ribs are short and the sternum is wide and thick. The scapular angle is not sharp, and the scapula is shallow and small.

(2) Magnetic resonance examination has clear value for judging the degree of compression of the spinal cord.

2. Ultrasound examination has some significance in prenatal monitoring of femoral development.

Diagnosis of cartilage hypoplasia

It is not difficult to make a diagnosis based on the patient's typical body and appearance, reduced limb size, and trident-like fingers.

Cartilage hypoplasia treatment

Growth hormone is effective in some cases. A few medical centers are evaluating the effects of human growth hormone on these children. Leg growth surgery can increase the height of some patients. However, this type of surgery requires a long treatment time and many complications.

1. Children with cartilage hypoplasia usually need to place the middle ear aqueduct, which helps prevent hearing loss caused by frequent ear infections.

2. Dental problems caused by crowded teeth may require extra care, aligners and removal of excess teeth.

3. Children often begin to be overweight in early childhood. Because being overweight can further exacerbate bone problems, nutritional guidance should be given to prevent obesity.

4. It is easy to cause lumbar pain due to lumbar spinal stenosis or disc herniation, and even paralysis of the lower limbs. Laminectomy decompression or lumbar discectomy is required.

5. For those with narrow occipital foramen and compression of the brainstem and spinal cord, the posterior occipital foramen should be decompressed to prevent sudden death. If there is Chiari deformity or hydrocephalus, corresponding treatment should be given according to the condition, such as decompression or shunt surgery.

6. Thoracolumbosacral braces have a certain effect on the prevention and treatment of thoracic and lumbar kyphotic deformities. Some scholars have suggested that when children begin to sit, they should wear TLSO until 2 years old. If the brace treatment is ineffective, the kyphotic deformity becomes worse Or kyphosis over 40 ° at 5 years of age. Spinal fusion should be performed.

7. When the fibula overgrows relative to the tibia, it can lead to angular deformities of the lower limbs and varus of the knee. Tibial osteotomy is feasible for those who have obvious symptoms or affect the appearance. It has also been reported to use fibula epiphysis fusion to correct the angular deformity of the lower extremity, but the effect is not certain.

Prevention of cartilage hypoplasia

Because most cases are caused by unpredictable genetic mutations in unaffected parents. Genetic counseling can help selective births in sick adults. Early diagnosis and early treatment are the key to the prevention and treatment of this disease. If the baby hasn't died, he can do all kinds of work as an adult, with a good prognosis.