pediatric osteogenesis imperfecta
Introduction
Introduction to pediatric osteogenesis Osteogenesis imperfecta (also known as fragile bone disease) is characterized by systemic connective tissue abnormalities. It is characterized by multiple fractures, blue sclera, progressive deafness, tooth changes, joint relaxation and skin abnormalities. Genetics are mostly autosomal dominant, and some cases show autosomal recessive inheritance. Cases of hereditary inheritance have also been reported. basic knowledge Sickness ratio: 0.05% Susceptible people: infants and young children Mode of infection: non-infectious Complications: fracture, flat foot, joint dislocation, deafness
Cause
Pediatric osteogenesis imperfecta
(1) Causes of the disease
In addition to a small number of cases, osteogenesis imperfecta is a malignant dominant genetic disease caused by mutation of one of the two chains forming type I collagen, and two copies of the 21 strand (encoded on chromosome 17) and 22 strands. A replication strand (encoded on chromosome 7) constitutes a repeat of about 1000 amino acids with glycine-XY, a triple helix configuration, and three triple helix structures intertwined to form a supercoiled structure. Type I collagen is the major structural protein of bone and connective tissue, and a few congenital osteogenesis imperfecta are positive recessive inheritance.
(two) pathogenesis
Mainly in the formation of skin, tendons, bones, cartilage and other connective tissue, the main component of collagen dysplasia, some authors reported that the patient's collagen tissue in the proline is too much, when the patient takes oral proline, blood The peak of endogenous proline is lower than that of normal children.
In the bone aspect, the osteoblast production is reduced or the activity is reduced, and alkaline phosphatase cannot be produced, or both cases are combined, so that the subperiosteal osteogenesis and the endochondral ossification are hindered, and the osteogenesis cannot be performed normally. The change is that the trabecular bone in the cancellous and cortical bones becomes fine and calcified, and there are clusters of chondrocytes, cartilage-like tissues and calcified bone-like tissues, and calcium deposition of bones. Normally, the above pathological changes cause bone fragility and bone softening.
Prevention
Pediatric osteogenesis imperfect prevention
Avoiding close relatives marriage: The intelligence of children with children born in close relatives is much worse than that of non-close relatives, and the incidence rate is very high. So be sure to avoid getting close to marriage.
Avoid old age: the childbearing age is best not to exceed 35 years old, because the aged women's cells are aging, susceptible to external virus infection, individuals formed after fertilization are prone to chromosomal diseases.
Conducting fertility counseling: Have you ever had a child with mental retardation or disability, or if the child died of illness, and whether the child will have the same situation; the woman is a habitual abortion, can he give birth again, how to prevent it; women have suffered during pregnancy Whether it affects the fetus, whether it has been treated with certain drugs, has been exposed to chemical poisons, or has worked in a radioactively contaminated position. Through consultation, the doctor will perform necessary examinations on both sides of the couple, and will give a treatment method and accurate advice.
Complication
Pediatric osteogenesis imperfecta complications Complications, flat foot joint dislocation, deafness
Congenital osteogenesis imperfecta often due to intracranial hemorrhage to the stillbirth, delayed osteogenesis insufficiency can cause repeated fractures, often formed into angular deformities, the formation of pseudo-arthrosis, etc., can occur valgus foot, flat feet, habitual joint dislocation is also more common, There are incomplete teeth, progressive deafness and so on.
Symptom
Symptoms of osteogenesis imperfecta in children Common symptoms Joint capsule relaxation of the dead fetus Rear spine blue sclera Osteoporosis Head enlargement Joint deformity Camelback intrauterine fracture Hydrocephalus
There are two types of clinical types:
1. Congenital osteogenesis imperfecta: It is a serious type. There are multiple fractures at birth. Slight trauma in the labor process or in the uterus can cause fractures. The limbs are short, deformed and have a rubbing sound. The skull is membranous, this type of disease Children often die from intracranial hemorrhage.
2. Delayed osteogenesis imperfects: worse than congenital type, normal at birth, severe cases can occur in infancy fractures; light fractures occur later, the lightest only sclera blue without fractures, delayed type The main complaint is to walk late, usually only after the fracture to seek medical treatment, the congenital and delayed type of severe disease, often lose normal body shape, limbs after fracture, and kyphosis and scoliosis and kyphosis, forehead width, frontal bone The anterior process, the humerus protrudes to both sides, the occipital bone protrudes, the head is enlarged, the left and right diameter is wide, and the anteroposterior diameter is short, so that the skull is disproportionate and triangular.
Scleral blue staining is the most common, occasionally normal sclera, because the sclera is thin and transparent, so that the pigment in the eye is visible, from deep sky blue to light blue, the so-called "Saturn ring" is a very common sign, which is white sclera tight For the reason of the cornea, some patients may have hyperopia and the cornea may be turbid.
Bone fragile system is a prominent feature of this disease. Mild trauma can cause fracture even if it is muscle contraction. The number of fractures depends on the type of the disease. In severe cases, there can be more than 100 fractures at the time of birth. There are fractures at the beginning, and the lower limbs are vulnerable to trauma. Therefore, there are many opportunities for fractures. Once a fracture occurs, it is easy to repeatedly fracture due to the angular deformity of the limb and the extensive atrophy caused by long-term braking. The pain in the fracture of the child is very small. It has become accustomed to multiple fractures, the fracture healing rate is normal, the epiphysis is very large, and it resembles osteosarcoma on X-ray photographs.
Long bone fractures can cause various angular bending deformities. If you do not brake, you can form a pseudo-articular joint. A slight fracture of the epiphysis can lead to early healing of the cocoon. The deformity of the female pelvic bone can affect future childbirth.
Low muscle tone, walking weakness, often easy to fall, skin is thin, like translucent, subcutaneous bleeding, capillary fragility test positive, surgical scar scars after surgery.
Spinal kyphosis and scoliosis can be caused by spinal compression fractures and ligament relaxation. The joints can be loosened by the ligaments and joint capsules, and the valgus foot, flat feet and habitual joint dislocation are also common.
Due to the lack of dentin, deciduous and permanent teeth can be affected. The enamel originating from the ectoderm is normal, the teeth are fragile, and dental caries are prone to occur. The teeth are often yellow-brown, gray-yellow or transparent blue, and more dysplastic. Poor bite, if the tooth is infringed alone, it is called incomplete or hereditary dysplasia.
Progressive deafness begins at different ages and is more common after puberty. It can be conductive or neurological deafness caused by ear sclerosis or auditory nerve compression. Some patients may have no hearing impairment, and some patients may be screaming. .
Examine
Pediatric osteogenesis insufficiency examination
Patients with blood calcium, phosphorus and ALP are generally normal, a small number of patients with ALP can also be increased, urinary hydroxyproline increased, some with amino acid urine and mucopolysaccharide urine, 2 / 3 patients with elevated serum T4, due to increased thyroxine, white blood cells Oxidative metabolism is hyperthyroidism with platelet aggregation disorder.
1.X-ray performance
(1) Joints: There are four main changes: one part of the patient may cause depression of the acetabulum and femoral head to the pelvis due to osteomalacia; 2 the intramedullary osteogenesis of the backbone may cause the bone to become thinner, but due to cartilage calcification and The osteogenesis of the cartilage is still normal, and the bone ends of the joints are relatively large; in most of the patients, there are most calcifications in the epiphysis, which may be due to the unabsorbed calcium in the cartilage during cartilage ossification; 4 pseudo pseudoarticular formation Due to multiple fractures, cartilage spasm is formed at the fracture, and the X-ray film looks like pseudo-articular formation.
(2) Bone: There are different bone damages in early-onset and late-onset osteogenesis imperfecta. Early-onset patients are often characterized by multiple fractures of the long bones with osteophyte formation and bone deformation; late-onset patients have obvious osteoporosis Multiple fractures, long bones bent or femur short and thick "accordion"-like changes, the backbone is too thin or the backbone is too thick, the bone is cystic or honeycomb-like, the long cortical defect is rough, the ribs are thinner, the lower edge is irregular or curved thickness Different, the finger is changed like peanut, the alveolar plate is absorbed, the scoliosis is convex, the vertebral body is flattened, or the vertebral body is increased, and the lower diameter is also increased. It can also be expressed as small vertebral body, pedicle growth, skull thin, and bone Existence, bulging anterior and posterior, occipital ptosis, the majority of the long bones of the long bones of the limbs have dense lines, and the density of the metaphyseal plate near the metaphysis is increased and uneven. MRI and CT examination can detect delayed osteogenesis imperfecta (osteogenesis) Imperfecta) hypertrophic callus formation at the lesion, sometimes resembling a bone tumor.
2. Ultrasound examination
Ultrasound examination of the fetal skeletal system can detect congenital bone development disorders early. Garjian's experience shows that three-dimensional ultrasound can obtain stereoscopic anatomical positioning, so it is better than two-dimensional ultrasound examination. The former is more likely to detect head, face and rib deformities.
Diagnosis
Diagnostic identification of osteogenesis in children
diagnosis
The four main diagnostic criteria are:
1. Osteoporosis and bone fragility increase.
2. Blue sclera.
3. Dentinogenesis imperfecta.
4. Premature otoclerosis.
Two of the above four items, especially the first two, can be diagnosed, and combined with imaging examination can help diagnose.
Differential diagnosis
1. Delayed juvenile osteoporosis: general osteoporosis, vertebral biconcave deformation or flat vertebral body, and lateral kyphosis and easy fracture of the spine, similar to osteogenesis imperfecta; but the latter still has a head Large, bilateral humerus external protrusion, flat skull base, small triangular face, blue sclera, multiple suture bones, and family history are different from the former.
The diagnosis of type I OI is sometimes very difficult. I should think of type I OI in the case of osteoporosis in adolescents or severe osteoporosis in perimenopause.
2. Bone softening and rickets: no bone brittle and easy to fold, no blue sclera, blurred front of the mineralization with a brush or cup mouth, widened cartilage disc, softening of the bone more common in pregnant or lactating women, with bone Pain, serum calcium, phosphorus are reduced.
3. Vitamin C deficiency: The patient also has osteoporosis, but there may be bleeding points under the skin, between the muscles and the epithelium. There may be severe pain and pseudo-sputum, and calcification may occur after the fracture is healed.
4. Osteosarcoma: A large number of osteophytes can occur in the fracture part of patients with osteogenesis imperfecta, most of which are benign, only a few have erythrocyte sedimentation rate and elevated blood ALP, and bone biopsy can be identified if necessary.
5. Hyperactivity of joints: Joint relaxation and hyperactivity are one of the characteristics of OI, and should be associated with other collagen-deficient diseases that cause this change, such as benign joint hyperactivity syndrome, Morquio syndrome, Ehlers-Danlos syndrome. , Marfan syndrome, Larsen syndrome, etc., in addition, special types of OI can be expressed as Cole-Carpenter syndrome, or adolescent osteoporosis, Ehlers-Danlos syndrome, OI combined with primary hyperparathyroidism, OI merger Dentinogenesis imperfecta (DI), OI-like syndrome, should be noted for identification.
